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JSON to LINQ to JSON
It is about 9:30pm and I am sitting on the train home. It has been quite tough organizing my life in the last months. This is not the promised follow-up on OpenGL. There has been no time to read any book.
Anyway, this post shows how to run LINQ queries on JSON. The use can be quite broad. Imagine a shell command executing your LINQ on any JSON file. You can query into depth and build complex return tree structures with 2 or more levels. LINQ itself is highly flexible. And – just to give it the right flair – it returns results in the good old JSON format.
You could even go a bit further and insert more than just a LINQ query. In theory, you could add any C# code at run-time. The changes to this program would be minuscule.
I have sufficiently commented the code. There is a minimum overhead to get the job done.
How it works:
- The JSON data is imported using the JavaScriptSerializer, which is part of the System.Web.Extensions library reference. We try to force the result into a Dictionary<string, object>. Do not lazily use ‘object’. Some type information would get lost. I played with this and got eg. arrays instead of ArrayLists.
- The resulting structure is then used to build classes. These are converted to legible C# source code.
- The LINQ command is inserted. You can see the result in the TextBox titled ‘C# source code output’.
- A compiler instance is created and some library references are added. We compile the generated source code at run-time and then execute the binary.
- A standard JSON object is returned, rudimentary formatted and displayed as the final result.
Btw. I have inserted a horizontal and a vertical GridSplitter into the WPF XAML. You can easily change the size of the TextBoxes while playing with this tool. A few JSON examples were also added.
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="LinqJson.MainWindow" Title="JSON LINQ JSON" Height="Auto" Width="876" d:DesignHeight="695">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="1*"/>
<RowDefinition Height="43*"/>
<RowDefinition Height="30"/>
<RowDefinition Height="150*"/>
<RowDefinition Height="30"/>
<RowDefinition Height="150*"/>
<RowDefinition Height="10*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="10*"/>
<ColumnDefinition Width="250*"/>
<ColumnDefinition Width="10"/>
<ColumnDefinition Width="250*"/>
<ColumnDefinition Width="10*"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Button Content="convert" Width="50" Height="30" Click="Button_Click" Grid.Row="1" HorizontalAlignment="Left" Grid.Column="1" Margin="0,8,0,7"/>
<StackPanel Grid.Column="1" Grid.Row="2" VerticalAlignment="Bottom" HorizontalAlignment="Left" Orientation="Horizontal" Height="27" >
<Label Content="JSON input" VerticalAlignment="Bottom" HorizontalAlignment="Left" Margin="0,1" />
<ComboBox Width="240" Margin="50,3,3,3" SelectionChanged="ComboBox_SelectionChanged" VerticalAlignment="Bottom">
<ComboBoxItem Name="ex1">Example 1</ComboBoxItem>
<ComboBoxItem Name="ex2">Example 2</ComboBoxItem>
<ComboBoxItem Name="ex3">Example 3</ComboBoxItem>
<ComboBoxItem Name="ex4">Example 4</ComboBoxItem>
</ComboBox>
</StackPanel>
<TextBox x:Name="JsonIn" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Grid.Column="1" Grid.Row="3"/>
<GridSplitter Grid.Column="2" Grid.RowSpan="999" HorizontalAlignment="Stretch" Width="10" Background="Transparent" ResizeBehavior="PreviousAndNext"/>
<GridSplitter Grid.Row="4" Grid.ColumnSpan="999" VerticalAlignment="Top" HorizontalAlignment="Stretch" Height="10" Background="Transparent" ResizeBehavior="PreviousAndNext" />
<Label Content="JSON output" Grid.Column="3" Grid.Row="2" VerticalAlignment="Bottom" />
<TextBox x:Name="JsonOut" VerticalAlignment="Stretch" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Grid.Column="3" Grid.Row="3" />
<Label Content="C# source code output" Grid.Column="3" Grid.Row="4" VerticalAlignment="Bottom" />
<TextBox x:Name="CSharpSourceCode" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Grid.Column="3" Grid.Row="5" />
<Label Content="LINQ input" Grid.Column="1" Grid.Row="4" VerticalAlignment="Bottom"/>
<TextBox x:Name="LinqIn" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" Grid.Column="1" Grid.Row="5" />
</Grid>
</Window>
using Microsoft.CSharp;
using System;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using System.Windows;
using System.Windows.Controls;
namespace LinqJson {
public partial class MainWindow : Window {
public MainWindow() {
InitializeComponent();
} // constructor
private void Button_Click(object sender, RoutedEventArgs e) {
// --------------------------------------------------
// get the JSON input
// --------------------------------------------------
string lJsonIn = JsonIn.Text;
// --------------------------------------------------
// construct the C# source code (class hierarchy)
// --------------------------------------------------
Converter lConverter = new Converter();
Dictionary<string, object> lTree = lConverter.JsonToDictionary(lJsonIn);
lConverter.DictionariesToClasses("root", 0, lTree);
var lStringBuilder = new StringBuilder();
lConverter.BuildClasses(lStringBuilder);
string lCSharpSourceCode = lConverter.GetUsings() + lStringBuilder.ToString();
// --------------------------------------------------
// add the LINQ command to the source code
// --------------------------------------------------
string lLinq = LinqIn.Text;
string lEntryPoint = "\n\n";
lEntryPoint += "public class baseClass {\n";
lEntryPoint += " public static object executeLinq(string xJson) {\n";
lEntryPoint += " xJson = xJson.Trim();";
lEntryPoint += " if (xJson[0] == '[') xJson = \"{home: \" + xJson + \"}\";";
lEntryPoint += " var lSerializer = new JavaScriptSerializer();\n";
lEntryPoint += " var root = lSerializer.Deserialize<Class_root>(xJson);\n";
lEntryPoint += " var lResult = " + lLinq.Replace("\n", "\n ") + ";\n";
lEntryPoint += " return lSerializer.Serialize(lResult);\n";
lEntryPoint += " }\n";
lEntryPoint += "}\n";
lCSharpSourceCode += lEntryPoint;
// --------------------------------------------------
// display the source code
// --------------------------------------------------
CSharpSourceCode.Text = lCSharpSourceCode;
// --------------------------------------------------
// compile the source code
// --------------------------------------------------
var lProviderOptions = new Dictionary<string, string>();
lProviderOptions.Add("CompilerVersion", "v4.0");
var lCSharpCodeProvider = new CSharpCodeProvider(lProviderOptions);
var lCompilerParameters = new CompilerParameters();
lCompilerParameters.ReferencedAssemblies.Add("System.dll");
lCompilerParameters.ReferencedAssemblies.Add("System.Core.dll");
lCompilerParameters.ReferencedAssemblies.Add("System.Data.Linq.dll");
lCompilerParameters.ReferencedAssemblies.Add("System.Threading.dll");
lCompilerParameters.ReferencedAssemblies.Add("System.Web.Extensions.dll");
lCompilerParameters.ReferencedAssemblies.Add("System.Xml.Linq.dll");
lCompilerParameters.GenerateInMemory = true;
lCompilerParameters.GenerateExecutable = false; // not required, we don't have a Main() method
lCompilerParameters.IncludeDebugInformation = true;
var lCompilerResults = lCSharpCodeProvider.CompileAssemblyFromSource(lCompilerParameters, lCSharpSourceCode);
if (lCompilerResults.Errors.HasErrors) {
var lError = new StringBuilder();
foreach (CompilerError lCompilerError in lCompilerResults.Errors) {
lError.AppendLine(lCompilerError.ErrorNumber + " => " + lCompilerError.ErrorText + Environment.NewLine);
}
JsonOut.TextWrapping = TextWrapping.Wrap;
JsonOut.Text = lError.ToString();
return;
}
JsonOut.TextWrapping = TextWrapping.NoWrap;
// --------------------------------------------------
// execute the compiled code
// --------------------------------------------------
Assembly lAssembly = lCompilerResults.CompiledAssembly;
Type lProgram = lAssembly.GetType("baseClass");
MethodInfo lMethod = lProgram.GetMethod("executeLinq");
object lQueryResult = lMethod.Invoke(null, new object[] { lJsonIn }); // returns a JSON string object
// --------------------------------------------------
// rudimentary JSON output formatting
// --------------------------------------------------
string lJsonOut = lQueryResult.ToString();
lJsonOut = lJsonOut.Replace(",", ",\n");
lJsonOut = lJsonOut.Replace(",{", ",{\n");
lJsonOut = lJsonOut.Replace("]", "]\n");
JsonOut.Text = lJsonOut;
} //
private void ComboBox_SelectionChanged(object xSender, SelectionChangedEventArgs e) {
var lComboBox = xSender as ComboBox;
switch (lComboBox.SelectedIndex) {
case 0:
JsonIn.Text = "{\n \"number\": 108.541,\n \"datetime\": \"1975-03-13T10:30:00\" ,\n \"serialnumber\": \"SN1234\",\n \"more\": {\n \"field1\": 123,\n \"field2\": \"hello\"\n },\n \"array\": [\n {\"x\": 2.0},\n {\"x\": 3.0},\n {\"x\": 4.0}\n ]\n}";
LinqIn.Text = "from a in root.array\nwhere a.x > 2.0M\nselect a";
break;
case 1:
JsonIn.Text = "[ 1, 9, 5, 7, 1, 4 ]";
LinqIn.Text = "from a in root.home\nwhere ((a == 4) || (a == 1))\nselect a";
break;
case 2:
JsonIn.Text = "{myLuckyNumbers: [ 1, 9, 5, 26, 7, 1, 4 ]}";
LinqIn.Text = "from x in root.myLuckyNumbers\nwhere x % 2 == 0\nselect new { simple=x, square=x*x, text=\"Field\"+x.ToString(), classInClass=new {veryOdd=x/7.0, lol=\":D\"}}";
break;
case 3:
string s;
s = "{\"mainMenu\": {\n";
s += " \"info\": \"Great tool.\",\n";
s += " \"value\": 100.00,\n";
s += " \"menu\": {\n";
s += " \"subMenu\": [\n";
s += " {\"text\": \"New\", \"onclick\": \"NewObject()\"},\n";
s += " {\"text\": \"Open\", \"onclick\": \"Load()\"},\n";
s += " {\"text\": \"Close\", \"onclick\": \"ByeBye()\"},\n";
s += " {\"text\": \"NNN\", \"onclick\": \"Useless()\"}\n";
s += " ]}\n";
s += "}}\n";
JsonIn.Text = s;
LinqIn.Text = "root.mainMenu.menu.subMenu.Where(t => t.text.StartsWith(\"N\")).Last();";
break;
default:
break;
}
} //
} // class
} // namespace
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Script.Serialization; // requires reference to System.Web.Extensions, used by the JavaScriptSerializer
namespace LinqJson {
public class Converter {
private Dictionary<string, object> _Classes = new Dictionary<string, object>();
public string GetUsings() {
string s;
s = "using System;\n";
s += "using System.Collections.Generic;\n";
s += "using System.Linq;\nusing System.Text;\n";
s += "using System.Threading.Tasks;\n";
s += "using System.Collections;\n";
s += "using System.Web.Script.Serialization;\n\n";
return s;
} //
public Dictionary<string, object> JsonToDictionary(string xJson) {
xJson = xJson.Trim();
if (xJson[0] == '[') xJson = "{home: " + xJson + "}"; // nameless arrays cannot be converted to dictionaries
var lJavaScriptSerializer = new JavaScriptSerializer();
try { return lJavaScriptSerializer.Deserialize<Dictionary<string, object>>(xJson); }
catch (Exception) { return null; }
} //
public void BuildClasses(StringBuilder xStringBuilder) {
foreach (var lClass in _Classes) {
Dictionary<string, object> lMembers = lClass.Value as Dictionary<string, object>;
if (lMembers == null) continue;
if (lMembers.Count <= 0) continue;
xStringBuilder.Append("public class Class_");
xStringBuilder.Append(lClass.Key);
xStringBuilder.AppendLine(" {");
foreach (var lMember in lMembers) {
object lValue = lMember.Value;
string lKey = lMember.Key;
Type lType = (lValue == null) ? typeof(object) : lMember.Value.GetType();
xStringBuilder.Append(new String(' ', 2));
xStringBuilder.Append("public ");
if (lType.IsValueType || (lValue is string)) {
xStringBuilder.Append(lType.Name);
xStringBuilder.Append(" ");
xStringBuilder.Append(lKey);
xStringBuilder.AppendLine(";");
}
else if (lValue is Dictionary<string, object>) {
xStringBuilder.Append("Class_");
xStringBuilder.Append(lKey);
xStringBuilder.Append(" ");
xStringBuilder.Append(lKey);
xStringBuilder.AppendLine(";");
}
else if (lValue is ArrayList) {
ArrayList lArrayList = lValue as ArrayList;
var lMemberType = ArrayListType(lArrayList); // differentiate between the contents of the list
if (lMemberType.IsValueType || (lMemberType.Name == "String")) {
//xStringBuilder.Append(lMemberType.Name.Replace("`2")); // Dictionaries use name "Dictionary`2"
xStringBuilder.Append(" List<"); xStringBuilder.Append(lMemberType.Name); xStringBuilder.Append("> ");
xStringBuilder.Append(lKey);
xStringBuilder.AppendLine(";");
}
else {
// a class
xStringBuilder.Append("List<Class_" + lKey + "> ");
xStringBuilder.Append(lKey);
xStringBuilder.AppendLine(";");
}
}
}
xStringBuilder.AppendLine(" }");
xStringBuilder.AppendLine();
}
} //
public void DictionariesToClasses(string xRootName, int xIndent, object xObject) {
if (xObject == null) return;
Type lType = xObject.GetType();
if (lType.IsValueType || (xObject is string)) return;
var lDictionary = xObject as Dictionary<string, object>;
if (lDictionary != null) {
object lObj;
if (!_Classes.TryGetValue(xRootName, out lObj)) {
_Classes.Add(xRootName, lDictionary);
}
else {
foreach (var lKeyValuePair in lDictionary) {
// This is a weakness of the program.
// Two JSON objects must not use the same name.
// We would have to compare the JSON objects and determine wether to create multiple or just one C# class.
_Classes[lKeyValuePair.Key] = lKeyValuePair.Value; // object type will be overridden !!!!!!
}
return;
}
foreach (var lKeyValuePair in lDictionary) {
DictionariesToClasses(lKeyValuePair.Key, xIndent, lKeyValuePair.Value);
}
return;
}
var lArrayList = xObject as ArrayList;
if (lArrayList != null) {
object lObj;
if (!_Classes.TryGetValue(xRootName, out lObj)) {
lDictionary = new Dictionary<string, object>();
_Classes.Add(xRootName, lDictionary);
}
else lDictionary = lObj as Dictionary<string, object>;
var lElementType = ArrayListType(lArrayList);
if (lElementType == typeof(Dictionary<string, object>)) {
var lList = lArrayList.Cast<Dictionary<string, object>>().ToList(); // upgrade our object to have stronger types
foreach (var lDict in lList) {
foreach (var lKeyValuePair in lDict) {
lDictionary[lKeyValuePair.Key] = lKeyValuePair.Value; // object type will be overridden !!!!!!
}
}
foreach (var lKeyValuePair in lDictionary) {
DictionariesToClasses(lKeyValuePair.Key, xIndent, lKeyValuePair.Value);
}
}
return;
}
} //
private void Append(StringBuilder xStringbuilder, int xIndent, string xString) {
xStringbuilder.Append(new String(' ', xIndent));
xStringbuilder.Append(xString);
} //
private void Newline(StringBuilder xStringbuilder) {
xStringbuilder.AppendLine();
} //
private Type ArrayListType(ArrayList xArrayList) {
var lTypes = new Dictionary<string, Type>();
Type lType;
string lTypeName;
foreach (object o in xArrayList) {
if (o == null) lType = typeof(object);
else lType = o.GetType();
lTypeName = lType.Name;
if (!lTypes.ContainsKey(lTypeName)) lTypes.Add(lTypeName, lType);
}
if (lTypes.Count == 1) return lTypes.Values.First(); // distinct
return typeof(object);
} //
} // class
} // namespace
OpenTK, entering the C# 3D world
I was amazed how short the source code can be to show complex moving objects. It does take a bit of research and the OpenTK library though. There are a lot of very good YouTube tutorials out there. Not necessarily about OpenTK, but plenty about OpenGL, which is what OpenTK is using.
I asked my daughters to draw some Minecraft style avatars with a simple icon editor. They had their fun and I got something to display in 3D. I stored three icon files (Freya.ico, Merlin.ico and Steve.ico) in a subfolder called ‘Resources’.
Change the file properties. ‘Build Action’ should be set to ‘None’, because you don’t have to compile these files. And you don’t want to copy the files each time you run the compiler. Simply set ‘Copy to Output Directory’ to ‘Copy if newer’.
The next step is to install and reference the OpenTK library (OpenTK, OpenTK.Compatibility and OpenTK.GLControl). Be aware that there is no real WPF support for OpenTK. You only host a Winform control within WPF. Therefore you should also reference “WindowsFormsIntegration”.
You can also open a pure OpenTK window. But it is impossible to add further WPF controls to the same window then. We are far away from programming games, so it is always a good option to leave the backdoor open for further WPF. You might want to add sliders to set angles and object positions.
Sorry for posting less for a while. I am working like a dog – leaving home at 6am and returning around 10pm during the week.
<Window x:Class="OpenTkControl.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:WinF="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
xmlns:OpenTK="clr-namespace:OpenTK;assembly=OpenTK.GLControl"
Title="OpenTK Demo" Height="600" Width="800">
<DockPanel LastChildFill="True">
<WindowsFormsHost x:Name="WinFormsContainer" Background="Transparent" DockPanel.Dock="Top" >
<OpenTK:GLControl x:Name="OpenTkControl"
Paint="OpenTkControl_Paint" Dock="Fill" />
</WindowsFormsHost>
</DockPanel>
</Window>
using OpenTK;
using OpenTK.Graphics.OpenGL;
using System;
using System.Drawing;
using System.Windows;
using System.Windows.Threading;
namespace OpenTkControl {
public partial class MainWindow : Window {
private DispatcherTimer _Timer;
private DateTime _ProgramStartTime;
public MainWindow() {
InitializeComponent();
_ProgramStartTime = DateTime.Now;
_Timer = new DispatcherTimer(DispatcherPriority.Send);
_Timer.IsEnabled = true;
_Timer.Interval = new TimeSpan(0, 0, 0, 0, 30);
_Timer.Tick += OnTimer;
_Timer.Start();
} // constructor
void OnTimer(object sender, EventArgs e) {
OpenTkControl.Invalidate();
} //
private void OpenTkControl_Paint(object sender, System.Windows.Forms.PaintEventArgs e) {
GLControl lControl = OpenTkControl;
// Reset the depth and color buffer.
// We want to render a new world. We do not want to continue with a previous rendering.
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
// Create a projection matrix transforming camera space to raster space. (google for "view frustum")
// Which is like: Press the 3D world and make it flat like a pancake, so that it does fit on the 2D screen.
// All points between a distance of 1 and 1000 will be taken into account.
float lAngleView = 1.2f; // y direction (in radians)
float lAspectRatio = 4f / 3f; // width / height
float lDistanceToNearClipPlane = 1f;
float lDistanceToFarClipPlane = 1000f;
Matrix4 lPerspective = Matrix4.CreatePerspectiveFieldOfView(lAngleView, lAspectRatio, lDistanceToNearClipPlane, lDistanceToFarClipPlane);
GL.MatrixMode(MatrixMode.Projection); GL.LoadIdentity(); GL.LoadMatrix(ref lPerspective);
// camera setup
Vector3 lCameraLocation = new Vector3(100f, 10f, 0f);
Vector3 lCameraLookingAt = new Vector3(0f, 0f, 0f); // look at the center of the coordinate system
Vector3 lCameraWhatIsUpside = new Vector3(0f, 1f, 0f); // classical way to hold a camera
Matrix4 lCamera = Matrix4.LookAt(lCameraLocation, lCameraLookingAt, lCameraWhatIsUpside);
GL.MatrixMode(MatrixMode.Modelview); GL.LoadIdentity(); GL.LoadMatrix(ref lCamera);
// this is the size on the screen
GL.Viewport(0, 0, lControl.Width, lControl.Height);
// only draw the nearest pixels and not pixels that are actually hidden by other pixels
GL.Enable(EnableCap.DepthTest);
GL.DepthFunc(DepthFunction.Less);
// set time dependent variables to generate movements
double lTotalMillis = DateTime.Now.Subtract(_ProgramStartTime).TotalMilliseconds;
double lTime1 = (lTotalMillis % 10000.0) / 10000.0; // between 0 and 1
double lTime2 = (lTotalMillis % 2000.0) / 2000.0; // between 0 and 1
double lTimeRadians = lTime2 * 2.0 * Math.PI;
float lJump = (float)(-20.0 + 10.0 * Math.Sin(lTimeRadians));
float lRadius = -40f;
// add the comet
DrawComet(lTotalMillis);
// render the floor
GL.Rotate(360.0 * lTime1, 0.0, 1.0, 0.5); // rotate around y axis and half as much around z axis
DrawFloor();
// render objects
// from where we are; now rotate the objects into the opposite direction
GL.Rotate(-lTime1 * 360.0 * 2.0, 0.0, 1.0, 0.0); DrawAvatar("Merlin", -30f, lRadius);
GL.Rotate(60.0, 0.0, 1.0, 0.0); DrawAvatar("Freya", lJump, lRadius);
GL.Rotate(60.0, 0.0, 1.0, 0.0); DrawAvatar("Steve", -30f, lRadius);
GL.Rotate(60.0, 0.0, 1.0, 0.0); DrawAvatar("Merlin", lJump, lRadius);
GL.Rotate(60.0, 0.0, 1.0, 0.0); DrawAvatar("Freya", -30f, lRadius);
GL.Rotate(60.0, 0.0, 1.0, 0.0); DrawAvatar("Steve", lJump, lRadius);
// render the cube in the center
//GL.Rotate(360f * lTime2, 0f, 0f, 0f); // <= this kind of rotation lets the box bounce and change its size
DrawCube(Color.SteelBlue, Color.DarkBlue, 0f, -25f, 0f, 8f, false);
OpenTK.Graphics.GraphicsContext.CurrentContext.VSync = true; // caps GPU frame rate
lControl.SwapBuffers(); // display our newly generated buffer with all objects
} //
private void DrawAvatar(string xName, float yShift, float zShift) {
Icon lIcon = new Icon("Resources/" + xName + ".ico");
Bitmap lBitmap = lIcon.ToBitmap();
int lWidth = lBitmap.Width; float lHalfWidth = lWidth / 2f;
int lHeight = lBitmap.Height; float lHalfHeight = lHeight;
for (int y = 0; y < lHeight; y++) {
for (int x = 0; x < lWidth; x++) {
Color lColor = lBitmap.GetPixel(x, y);
if (lColor.A != 0) DrawCube(lColor, lColor, (float)x - lHalfWidth, lHeight + yShift - (float)y, (float)zShift, 1f, true);
}
}
} //
private void DrawFloor() {
for (int x = -100; x < 100; x += 10) {
for (int z = -100 + (x % 10 == 0 ? 5 : 0); z < 100; z += 10) {
DrawCube(Color.White, Color.Gray, x, -30f, z, 5f, false);
}
}
} //
private void DrawComet(double xTotalMillis) {
xTotalMillis = (xTotalMillis % 7000.0) / 7000.0; // between 0 and 1
GL.PushMatrix();
GL.LoadIdentity();
GL.Translate(xTotalMillis * 30f - 40f , 40f, 400f * xTotalMillis - 400f);
GL.Rotate(360f * xTotalMillis * 3f, 1f, 1f, 1f);
DrawTetrahedron(Color.Orange, Color.OrangeRed, 0f, 0f, 0f, 8f);
GL.Rotate(180f, 1f, 0f, 0f);
DrawTetrahedron(Color.Orange, Color.OrangeRed, 0f, 0f, 0f, 8f);
GL.PopMatrix();
} //
private void DrawCube(System.Drawing.Color xColor, System.Drawing.Color xColor2, float X, float Y, float Z, float xWidth, bool xHasDarkBack) {
float lHalfWidth = xWidth / 2f;
float lTop = Y + lHalfWidth;
float lBottom = Y - lHalfWidth;
float lLeft = X - lHalfWidth;
float lRight = X + lHalfWidth;
float lFront = Z + lHalfWidth;
float lRear = Z - lHalfWidth;
GL.Begin(PrimitiveType.Quads);
Color lColor; if (xHasDarkBack) lColor = Color.DarkGray; else lColor = xColor;
Color lColor2; if (xHasDarkBack) lColor2 = Color.DarkGray; else lColor2 = xColor2;
Action lPointFrontTopLeft = () => { GL.Color3(xColor); GL.Vertex3(lLeft, lTop, lFront); };
Action lPointFrontTopRight = () => { GL.Color3(xColor2); GL.Vertex3(lRight, lTop, lFront); };
Action lPointFrontBottomLeft = () => { GL.Color3(xColor2); GL.Vertex3(lLeft, lBottom, lFront); };
Action lPointFrontBottomRight = () => { GL.Color3(xColor2); GL.Vertex3(lRight, lBottom, lFront); };
Action lPointRearTopLeft = () => { GL.Color3(lColor); GL.Vertex3(lLeft, lTop, lRear); };
Action lPointRearTopRight = () => { GL.Color3(lColor2); GL.Vertex3(lRight, lTop, lRear); };
Action lPointRearBottomLeft = () => { GL.Color3(lColor2); GL.Vertex3(lLeft, lBottom, lRear); };
Action lPointRearBottomRight = () => { GL.Color3(lColor2); GL.Vertex3(lRight, lBottom, lRear); };
// front square
lPointFrontTopLeft(); lPointFrontTopRight(); lPointFrontBottomRight(); lPointFrontBottomLeft();
// rear square
lPointRearTopLeft(); lPointRearTopRight(); lPointRearBottomRight(); lPointRearBottomLeft();
// top square
lPointFrontTopLeft(); lPointFrontTopRight(); lPointRearTopRight(); lPointRearTopLeft();
// bottom square
lPointFrontBottomLeft(); lPointFrontBottomRight(); lPointRearBottomRight(); lPointRearBottomLeft();
// left square
lPointFrontTopLeft(); lPointRearTopLeft(); lPointRearBottomLeft(); lPointFrontBottomLeft();
// right square
lPointFrontTopRight(); lPointRearTopRight(); lPointRearBottomRight(); lPointFrontBottomRight();
GL.End();
} //
private void DrawTetrahedron(System.Drawing.Color xColor, System.Drawing.Color xColor2, float X, float Y, float Z, float xSideLength) {
float lDistMidToVertex = (float)Math.Sqrt(6.0) / 4f * xSideLength;
float lDistMidToFloor = (float)Math.Sqrt(6.0) / 12f * xSideLength;
float lHeight = (float)Math.Sqrt(2.0 / 3.0) * xSideLength; // = lDistMidToVertex + lDistMidToEdge
float lTop = Y + lDistMidToVertex;
float lBottom = Y - lDistMidToFloor;
float lRight = X + xSideLength / 2f;
float lLeft = X - xSideLength / 2f;
float lRear = Z - (float) (xSideLength * Math.Sqrt(3.0) / 3.0);
float lFront = Z + (float)(xSideLength * Math.Sqrt(3.0) / 6.0);
GL.Begin(PrimitiveType.Triangles);
Action lPointTop = () => { GL.Color3(xColor); GL.Vertex3(X, lTop, Z); };
Action lPointFrontBottomLeft = () => { GL.Color3(xColor2); GL.Vertex3(lLeft, lBottom, lFront); };
Action lPointFrontBottomRight = () => { GL.Color3(xColor); GL.Vertex3(lRight, lBottom, lFront); };
Action lPointRear = () => { GL.Color3(xColor2); GL.Vertex3(X, lBottom, lRear); };
// front triangle
lPointTop(); lPointFrontBottomLeft(); lPointFrontBottomRight();
// left triangle
lPointTop(); lPointFrontBottomLeft(); lPointRear();
// right triangle
lPointTop(); lPointFrontBottomRight(); lPointRear();
// bottom triangle
lPointFrontBottomLeft(); lPointFrontBottomRight(); lPointRear();
GL.End();
} //
} // class
} // namespace
Slogan / News Ticker / Scrolling Text in WPF (Part 2)
This is the follow-up of my last post.
I promised to enhance the scroll behavior. Here it is. You can influence the text in various ways. When the zoom factor turns negative you can even see upside down characters. Also the drift can turn negative; if so the wave moves to the left, but its peaks drift to the right.
Weirdly enough it is a lot of fun playing with the sliders and watching the wave change. Of course, we could still create far more complex movements. This source code here is providing the full basics. The rest is up to you.
What you can influence:
- text zoom (negative numbers turn the text upside down)
- scroll speed
- wave amplitude
- wave drift
- wave length
I had to slightly change the way the vectors are stored to enable zooming. The y-zero-line now is in the middle of the characters and not at the top anymore. Anything above that line is negative, anything below positive. Hence the vectors can be multiplied with a zoom factor without the need to recalculate the position in the WPF control.
<Window x:Class="Ticker.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Ticker"
Height="250"
Width="500"
Loaded="Window_Loaded">
<DockPanel x:Name="MyDockPanel"
SizeChanged="MyImage_SizeChanged"
LastChildFill="True">
<Grid DockPanel.Dock="Top">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="110"/>
<ColumnDefinition Width="50*"/>
<ColumnDefinition Width="110"/>
<ColumnDefinition Width="50*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Label Content="calculation speed" Grid.Row="0"
HorizontalAlignment="Right" Padding="0,0,0,0"/>
<TextBox Name="Info"
Grid.Row="0" Grid.Column="1"/>
<Label Content="zoom" Grid.Row="0" Grid.Column="2"
HorizontalAlignment="Right" Padding="0,0,0,0"/>
<Slider Minimum="-1.0" Maximum="1.0" Value="1.0"
ValueChanged="Slider_Zoom_ValueChanged"
Grid.Row="0" Grid.Column="3" />
<Label Content="scroll speed" Grid.Row="1" Grid.Column="0"
HorizontalAlignment="Right" Padding="0,0,0,0"/>
<Slider Minimum="0.5" Maximum="8.0" Value="2.0"
ValueChanged="Slider_ScrollSpeed_ValueChanged"
Grid.Row="1" Grid.Column="1" />
<Label Content="wave amplitude" Grid.Row="1" Grid.Column="2"
HorizontalAlignment="Right" Padding="0,0,0,0"/>
<Slider Minimum="0.0" Maximum="100.0" Value="50.0"
ValueChanged="Slider_Amplitude_ValueChanged"
Grid.Row="1" Grid.Column="3" />
<Label Content="wave drift" Grid.Row="2" Grid.Column="0"
HorizontalAlignment="Right" Padding="0,0,0,0"/>
<Slider Minimum="-10.0" Maximum="10.0" Value="5.0"
ValueChanged="Slider_Drift_ValueChanged"
Grid.Row="2" Grid.Column="1" />
<Label Content="wave length" Grid.Row="2" Grid.Column="2"
HorizontalAlignment="Right" Padding="0,0,0,0"/>
<Slider Minimum="0.0" Maximum="2.0" Value="0.5"
ValueChanged="Slider_WaveLength_ValueChanged"
Grid.Row="2" Grid.Column="3" />
</Grid>
<Image Name="MyImage"
DockPanel.Dock="Top"
Stretch="None"
Width="{Binding ActualWidth, ElementName=MyDockPanel}"/>
</DockPanel>
</Window>
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
namespace Ticker {
public partial class MainWindow : Window {
private Thread _Thread;
private TextEngine _TextEngine = new TextEngine();
private float _WidthInPixels;
private double _Speed = 1.0; // number of pixels to shift per iteration
private AutoResetEvent _AutoResetEvent = new AutoResetEvent(true);
private BitmapImage _BitmapImage = null;
private string _ElapsedTime = string.Empty;
public MainWindow() {
InitializeComponent();
} // constructor
private void Window_Loaded(object sender, EventArgs e) {
DataContext = this;
_Thread = new Thread(Loop);
_Thread.Name = "MainLoop";
_Thread.IsBackground = true;
_Thread.Priority = ThreadPriority.AboveNormal;
_Thread.Start();
TimeSpan lInterval = new TimeSpan(0, 0, 0, 0, 50); // run each 50 ms
EventHandler lHandler = new EventHandler(OnTime);
DispatcherTimer lDispatcherTimer = new DispatcherTimer(lInterval, DispatcherPriority.Send, lHandler, this.Dispatcher);
} //
private void MyImage_SizeChanged(object sender, SizeChangedEventArgs e) {
DockPanel lDockPanel = sender as DockPanel;
if (lDockPanel == null) return;
using (var lGraphics = Graphics.FromHwnd(IntPtr.Zero)) {
_WidthInPixels = (float)(e.NewSize.Width * lGraphics.DpiX / 96.0);
}
} //
public void OnTime(object XSender, EventArgs e) {
BitmapImage lBitmapImage = _BitmapImage;
if (lBitmapImage == null) return;
MyImage.Source = lBitmapImage;
Line.adjustDrift();
Info.Text = _ElapsedTime;
_AutoResetEvent.Set();
} //
private void Loop() {
float lEnd = 0f;
int lSectionFrom = 0;
int lSectionTo = 0;
Stopwatch lStopwatch = new Stopwatch();
while (true) {
_AutoResetEvent.WaitOne();
lStopwatch.Restart();
float lWidthInPixel = _WidthInPixels; // copy the value to avoid changes during the calculation
if (lWidthInPixel <= 0.0) continue;
List<Line> lSection = _TextEngine.getVectorSection(ref lSectionFrom, ref lSectionTo, lEnd, lWidthInPixel);
// This value determines the speed.
// Even numbers give better results due to the rounding error nature of bitmaps.
// Odd numbers create jitter. Luckily humans have bad eyes, they cannot perceive it.
lEnd += (float)_Speed;
if (lSection == null) {
// end reached, reset text
lSectionFrom = 0;
lSectionTo = 0;
lEnd = 0f;
}
else {
Bitmap lBitmap = _TextEngine.VectorsToBitmap(lSection, lWidthInPixel);
_BitmapImage = _TextEngine.BitmapToImageSource(lBitmap);
}
_ElapsedTime = lStopwatch.ElapsedMilliseconds.ToString("#,##0");
//lStopwatch.Stop();
}
} //
private void Slider_ScrollSpeed_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) { _Speed = e.NewValue; }
private void Slider_Amplitude_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) { Line.Amplitude = (float)e.NewValue; }
private void Slider_Drift_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) { Line.Drift = (float)e.NewValue; }
private void Slider_WaveLength_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) { Line.WaveLength = (float)e.NewValue; }
private void Slider_Zoom_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) { Line.Zoom = (float)e.NewValue; }
} // class
} // namespace
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Windows.Media.Imaging;
namespace Ticker {
public class TextEngine {
private const float cFontHeight = 40f;
private const string cText = @"Die Gedanken sind frei, wer kann sie erraten, sie fliegen vorbei wie nächtliche Schatten. Kein Mensch kann sie wissen, kein Jäger erschießen mit Pulver und Blei: Die Gedanken sind frei! Ich denke was ich will und was mich beglücket, doch alles in der Still', und wie es sich schicket. Mein Wunsch und Begehren kann niemand verwehren, es bleibet dabei: Die Gedanken sind frei! Und sperrt man mich ein im finsteren Kerker, das alles sind rein vergebliche Werke. Denn meine Gedanken zerreißen die Schranken und Mauern entzwei: Die Gedanken sind frei! Drum will ich auf immer den Sorgen entsagen und will mich auch nimmer mit Grillen mehr plagen. Man kann ja im Herzen stets lachen und scherzen und denken dabei: Die Gedanken sind frei! Ich liebe den Wein, mein Mädchen vor allen, sie tut mir allein am besten gefallen. Ich sitz nicht alleine bei meinem Glas Weine, mein Mädchen dabei: Die Gedanken sind frei!";
private List<Line> _TextAsVectorChain = new List<Line>();
private Font _Font = new Font("Arial", cFontHeight, System.Drawing.FontStyle.Bold, GraphicsUnit.Pixel);
public TextEngine() {
// convert the entire text to vectors
float lPosition = 0;
Dictionary<char, List<Line>> lVectorCache = new Dictionary<char, List<Line>>();
char[] lChars = cText.ToCharArray();
foreach (char lChar in lChars) {
if (lChar == ' ') lPosition += 10; // distance for an empty space character
else {
List<Line> lOneCharVectors;
if (!lVectorCache.TryGetValue(lChar, out lOneCharVectors)) {
Bitmap lBitmap = CharToBitmap(lChar);
lOneCharVectors = BitmapToVectors(lBitmap);
lVectorCache.Add(lChar, lOneCharVectors);
}
float lNewPosition = lPosition;
foreach (Line lLine in lOneCharVectors) {
Line lClone = lLine.Clone();
lClone.X += lPosition;
lNewPosition = lClone.X;
_TextAsVectorChain.Add(lClone);
}
lPosition = lNewPosition + 4; // 4 == space between two characters
}
}
} // constructor
// Convert a bitmap to an ImageSource.
// We can then display the result in the WPF Image element.
public BitmapImage BitmapToImageSource(Bitmap xBitmap) {
using (MemoryStream lMemoryStream = new MemoryStream()) {
xBitmap.Save(lMemoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
lMemoryStream.Position = 0;
BitmapImage lBitmapImage = new BitmapImage();
lBitmapImage.BeginInit();
lBitmapImage.StreamSource = lMemoryStream;
lBitmapImage.CacheOption = BitmapCacheOption.OnLoad;
lBitmapImage.EndInit();
lBitmapImage.Freeze();
return lBitmapImage;
}
} //
// draw a single character into a bitmap
private Bitmap _Bitmap = null;
public Bitmap CharToBitmap(char xChar) {
_Bitmap = new Bitmap((int)(cFontHeight * 1.25f), (int)(cFontHeight * 1.25f));
using (Graphics lGraphics = Graphics.FromImage(_Bitmap)) {
lGraphics.Clear(Color.White);
lGraphics.DrawString(xChar.ToString(), _Font, Brushes.Black, 0f, 0f);
}
return _Bitmap;
} //
// Replicate the characters now by reading the vectors and drawing lines.
Pen lPen = new Pen(Color.Black, 2f);
public Bitmap VectorsToBitmap(List<Line> xLines, float xBitmapWidth) {
int lHeight = (int)cFontHeight + (int)Math.Abs(Line.Amplitude);
Bitmap lBitmap = new Bitmap((int)xBitmapWidth, lHeight);
lHeight /= 2; // half height, rounded down
using (Graphics lGraphics = Graphics.FromImage(lBitmap)) {
lGraphics.Clear(Color.White);
foreach (Line lLine in xLines) {
lGraphics.DrawLine(lPen, lLine.X, lLine.Y1 + lHeight, lLine.X, lLine.Y2 + lHeight);
}
}
return lBitmap;
} //
// Convert a single character to vectors.
private List<Line> BitmapToVectors(Bitmap xBitmap) {
int lXCoordinateOfFirstPixel = -1;
List<Line> lList = new List<Line>();
for (int x = 0, lWidth = xBitmap.Width; x < lWidth; x++) {
Line lVector = null;
for (int y = 0, lHeight = xBitmap.Height; y < lHeight; y++) {
Color lColor = xBitmap.GetPixel(x, y);
bool lIsWhite = lColor.B == 255;
if (lIsWhite) {
if (lVector != null) {
lList.Add(lVector);
lVector = null;
}
}
else {
int lHalfHeight = xBitmap.Height / 2;
if (lVector == null) {
if (lXCoordinateOfFirstPixel < 0) lXCoordinateOfFirstPixel = x; // to always start at zero for our vectors
lVector = new Line { X = x - lXCoordinateOfFirstPixel, Y1 = y - lHalfHeight, Y2 = y - lHalfHeight };
}
else lVector.Y2 = y - lHalfHeight;
}
}
}
return lList;
} //
// The text was converted to vectors.
// Now we cut out the sequence we need for the display.
internal List<Line> getVectorSection(ref int xSectionFrom, ref int xSectionTo, float xEnd, float xWidth) {
int lCount = _TextAsVectorChain.Count;
float lStart = xEnd - xWidth;
// find the right section
do {
xSectionTo++;
if (xSectionTo >= lCount) { xSectionTo = lCount - 1; break; }
if (xEnd < _TextAsVectorChain[xSectionTo].X) break;
} while (true);
do {
if (lStart < 0) break; // to allow empty spaces at the beginning of the slogan
if (xSectionFrom >= lCount) return null;
if (lStart < _TextAsVectorChain[xSectionFrom].X) break;
xSectionFrom++;
} while (true);
// clone that section
List<Line> lList = new List<Line>();
for (int x = xSectionFrom; x <= xSectionTo; x++) {
Line lClone = _TextAsVectorChain[x].Clone();
lClone.X -= lStart; // adjust the X-axis
lClone.RecalcYShift();
lList.Add(lClone);
}
return lList;
} //
} // class
} // namespace
using System;
namespace Ticker {
public class Line {
private float _Y1, _Y1Shift;
private float _Y2, _Y2Shift;
private static float _XDrift = 0f;
public float X { get; set; }
public static float Amplitude { get; set; } // This is the additional height needed for the vertical swing
public static float Drift { get; set; } // How fast does the wave crest/trough move?
public static float WaveLength { get; set; } // How wide is the wave?
public static float Zoom { get; set; } // Character zoom factor around the horizontal middle.
public static void adjustDrift() { _XDrift += Drift; }
public float Y1 {
get { return _Y1 * Zoom + _Y1Shift; }
set { _Y1 = value; }
} //
public float Y2 {
get { return _Y2 * Zoom + _Y2Shift; }
set { _Y2 = value; }
} //
public void RecalcYShift() {
double d = (double)(WaveLength * (X + _XDrift));
d = Math.IEEERemainder(d / 50.0, 1.99999999999);
float lAngle = (float)Math.Sin(Math.PI * d); // 0.0 <= d < 2.0 therefore -1.0 <= lAngle <= 1.0
float lShift = Amplitude / 2.0f * lAngle;
_Y1Shift = lShift;
_Y2Shift = lShift;
} //
public Line Clone() {
Line lLine = new Line();
lLine.X = X;
lLine.Y1 = _Y1;
lLine.Y2 = _Y2;
return lLine;
} //
} // class
} // namespace
Slogan / News Ticker / Scrolling Text in WPF
Oh, I used to write so called intros with scrolling text slogans at the bottom on the Commodore Amiga. The hardware was pretty much unalterable and you could easily work with the Blitter and Copper. The vertical blank beam on the monitor was my timer. These days are over. No more Assembler. And who cares about high and low byte these days?
I have to admit that using C# in combination with WPF is not the best approach for moving text around. You should directly talk to graphic cards for such. Anyway, it started with a short benchmark test and ended up with this example program. If you program properly, then you can make WPF do the job without any flickering.
You might wonder why my approach is quite indirect this time. I am not simply rendering text to the screen and then change its position. This program is slightly more complex. The reason is that I am planning a follow-up with more complex movements soon. I am planning to show you how to scroll text along the screen in a sinus curve while the curve itself behaves like a wave. Maybe I will add some topsy-turvy stuff as well. Hehe, it is not written yet.
This post is providing the basics to get prepared for the next step. Today, the text simply moves from the right to the left. And no worries about the end of the text. It is dealt with properly.
You can change the speed with the slider while the text field returns the calculation time in milliseconds. You can see that we still have some timing leeway. There are no issues with our frequency, which is 20 updates per second. The screen itself obviously updates more often. Its frequency has little to do with the one for showing new BitmapImages. Our thread loop takes less than 20 milliseconds.
How does the program work?
- A loop is running on an independent thread. This loop executes each time right after our WPF update. This well chosen moment avoids timing conflicts efficiently. The next BitmapImage is ready to be shown before the next WPF GUI update.
- At the beginning of the program we convert the entire text to vectors. The orientation of all vectors is vertical. Each x-value can consist of several vertical vectors. For instance the character “E” has 1 or 3 vertical vectors. The first vector is a straight vertical black line from the top to the bottom. When you are in the middle of the character, then you have three black and two white areas. We only convert the black parts. Imagine a vertical cut right through the middle from the top to the bottom.
- The conversion from “character to bitmap to vector” is NOT conducted in real-time. This is done during the program initialization as mentioned above. Only then we can run at full steam afterwards.
- We only change the precalculated vectors and render the bitmap in real-time – nothing else.
- These vectors are then drawn to bitmaps. These bitmaps are not dependent on the Dispatcher thread. We are still running at maximum speed. Before we can change the source for the Image control, we have to convert the Bitmap class to an ImageSource.
- This ImageSource is then assigned to the Image control during a DispatcherTimer event.
Once again the program was kept to a minimum length. Maybe I should have added some more classes. I hope I found the right length for this example program in the end.
This code was not straight forward. There had to be a learning curve … as usual. First, I tried some direct WPF binding. The timing was nearly out of control. So I gave up after a while. But I had some nice blog ideas in the meantime. We should enter the 3D world at some point, don’t you think so?
The 3D approach would most likely the best approach for our scrolling text as well. I expect the efficiency to be extreme. There are so many games with millions of mesh triangles rendered within milliseconds – this cannot be bad stuff. We could even use 3D features for showing 2D text.
This will surely require some profound research on my side. Don’t expect anything anytime soon. I am definitely not omniscient.
<Window x:Class="Ticker.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Ticker"
Height="130"
Width="400"
Loaded="Window_Loaded">
<StackPanel x:Name="MyStackPanel"
SizeChanged="MyImage_SizeChanged">
<DockPanel LastChildFill="True">
<Slider Width="300" DockPanel.Dock="Right"
Minimum="0.5" Maximum="8.0"
Value="2.0"
ValueChanged="Slider_ValueChanged" />
<TextBox Name="Info" DockPanel.Dock="Right"/>
</DockPanel>
<Image Name="MyImage"
Stretch="None"
Height="60"
Width="{Binding ActualWidth, ElementName=MyStackPanel}"/>
</StackPanel>
</Window>
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
namespace Ticker {
public partial class MainWindow : Window {
private Thread _Thread;
private TextEngine _TextEngine = new TextEngine();
private float _WidthInPixels;
private double _Speed = 1.0; // number of pixels to shift per iteration
private AutoResetEvent _AutoResetEvent = new AutoResetEvent(true);
private BitmapImage _BitmapImage = null;
private string _ElapsedTime = string.Empty;
public MainWindow() {
InitializeComponent();
} // constructor
private void Window_Loaded(object sender, EventArgs e) {
DataContext = this;
_Thread = new Thread(Loop);
_Thread.Name = "MainLoop";
_Thread.IsBackground = true;
_Thread.Priority = ThreadPriority.AboveNormal;
_Thread.Start();
TimeSpan lInterval = new TimeSpan(0, 0, 0, 0, 50); // run each 50 ms
EventHandler lHandler = new EventHandler(OnTime);
DispatcherTimer lDispatcherTimer = new DispatcherTimer(lInterval, DispatcherPriority.Send, lHandler, this.Dispatcher);
} //
private void MyImage_SizeChanged(object sender, SizeChangedEventArgs e) {
StackPanel lStackPanel = sender as StackPanel;
if (lStackPanel == null) return;
using (var lGraphics = Graphics.FromHwnd(IntPtr.Zero)) {
_WidthInPixels = (float)(e.NewSize.Width * lGraphics.DpiX / 96.0);
}
} //
public void OnTime(object XSender, EventArgs e) {
BitmapImage lBitmapImage = _BitmapImage;
if (lBitmapImage == null) return;
MyImage.Source = lBitmapImage;
Info.Text = _ElapsedTime;
_AutoResetEvent.Set();
} //
private void Loop() {
float lEnd = 0f;
int lSectionFrom = 0;
int lSectionTo = 0;
Stopwatch lStopwatch = new Stopwatch();
while (true) {
_AutoResetEvent.WaitOne();
lStopwatch.Restart();
float lWidthInPixel = _WidthInPixels; // copy the value to avoid changes during the calculation
if (lWidthInPixel <= 0.0) continue;
List<Line> lSection = _TextEngine.getVectorSection(ref lSectionFrom, ref lSectionTo, lEnd, lWidthInPixel);
// This value determines the speed.
// Even numbers give better results due to the rounding error nature of bitmaps.
// Odd numbers create jitter. Luckily humans have bad eyes, they cannot perceive it.
lEnd += (float)_Speed;
if (lSection == null) {
// end reached, reset text
lSectionFrom = 0;
lSectionTo = 0;
lEnd = 0f;
}
else {
Bitmap lBitmap = _TextEngine.VectorsToBitmap(lSection, lWidthInPixel);
_BitmapImage = _TextEngine.BitmapToImageSource(lBitmap);
}
_ElapsedTime = lStopwatch.ElapsedMilliseconds.ToString("#,##0");
lStopwatch.Stop();
}
} //
private void Slider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) {
_Speed = e.NewValue;
} //
} // class
} // namespace
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Windows.Media.Imaging;
namespace Ticker {
public class TextEngine {
private const string cText = @"Die Gedanken sind frei, wer kann sie erraten, sie fliegen vorbei wie nächtliche Schatten. Kein Mensch kann sie wissen, kein Jäger erschießen mit Pulver und Blei: Die Gedanken sind frei! Ich denke was ich will und was mich beglücket, doch alles in der Still', und wie es sich schicket. Mein Wunsch und Begehren kann niemand verwehren, es bleibet dabei: Die Gedanken sind frei! Und sperrt man mich ein im finsteren Kerker, das alles sind rein vergebliche Werke. Denn meine Gedanken zerreißen die Schranken und Mauern entzwei: Die Gedanken sind frei! Drum will ich auf immer den Sorgen entsagen und will mich auch nimmer mit Grillen mehr plagen. Man kann ja im Herzen stets lachen und scherzen und denken dabei: Die Gedanken sind frei! Ich liebe den Wein, mein Mädchen vor allen, sie tut mir allein am besten gefallen. Ich sitz nicht alleine bei meinem Glas Weine, mein Mädchen dabei: Die Gedanken sind frei!";
private List<Line> _TextAsVectorChain = new List<Line>();
public TextEngine() {
// convert the entire text to vectors
float lPosition = 0;
Dictionary<char, List<Line>> lVectorCache = new Dictionary<char, List<Line>>();
char[] lChars = cText.ToCharArray();
foreach (char lChar in lChars) {
if (lChar == ' ') lPosition += 10; // distance for an empty space character
else {
List<Line> lOneCharVectors;
if (!lVectorCache.TryGetValue(lChar, out lOneCharVectors)) {
Bitmap lBitmap = CharToBitmap(lChar);
lOneCharVectors = BitmapToVectors(lBitmap);
lVectorCache.Add(lChar, lOneCharVectors);
}
float lNewPosition = lPosition;
foreach (Line lLine in lOneCharVectors) {
Line lClone = lLine.Clone();
lClone.X += lPosition;
lNewPosition = lClone.X;
_TextAsVectorChain.Add(lClone);
}
lPosition = lNewPosition + 4; // 4 == space between two characters
}
}
} // constructor
// Convert a bitmap to an ImageSource.
// We can then display the result in the WPF Image element.
public BitmapImage BitmapToImageSource(Bitmap xBitmap) {
using (MemoryStream lMemoryStream = new MemoryStream()) {
xBitmap.Save(lMemoryStream, System.Drawing.Imaging.ImageFormat.Bmp);
lMemoryStream.Position = 0;
BitmapImage lBitmapImage = new BitmapImage();
lBitmapImage.BeginInit();
lBitmapImage.StreamSource = lMemoryStream;
lBitmapImage.CacheOption = BitmapCacheOption.OnLoad;
lBitmapImage.EndInit();
lBitmapImage.Freeze();
return lBitmapImage;
}
} //
// draw a single character into a bitmap
private Font _Font = null;
private Bitmap _Bitmap = null;
public Bitmap CharToBitmap(char xChar) {
if (_Font == null) {
_Font = new Font("Arial", 40.0f, System.Drawing.FontStyle.Bold, GraphicsUnit.Pixel);
_Bitmap = new Bitmap(60, 70);
}
using (Graphics lGraphics = Graphics.FromImage(_Bitmap)) {
lGraphics.Clear(Color.White);
lGraphics.DrawString(xChar.ToString(), _Font, Brushes.Black, 0f, 0f);
}
return _Bitmap;
} //
// Replicate the characters now by reading the vectors and drawing lines.
Pen lPen = new Pen(Color.Black, 2f);
public Bitmap VectorsToBitmap(List<Line> xLines, float xBitmapWidth) {
if (_Font == null) { _Font = new Font("Arial", 40.0f, System.Drawing.FontStyle.Bold, GraphicsUnit.Pixel); }
Bitmap lBitmap = new Bitmap((int)xBitmapWidth, 60);
using (Graphics lGraphics = Graphics.FromImage(lBitmap)) {
lGraphics.Clear(Color.White);
foreach (Line lLine in xLines) {
lGraphics.DrawLine(lPen, lLine.X, lLine.Y1, lLine.X, lLine.Y2);
}
}
return lBitmap;
} //
// Convert a single character to vectors.
private List<Line> BitmapToVectors(Bitmap xBitmap) {
int lXCoordinateOfFirstPixel = -1;
List<Line> lList = new List<Line>();
for (int x = 0, lWidth = xBitmap.Width; x < lWidth; x++) {
Line lVector = null;
for (int y = 0, lHeight = xBitmap.Height; y < lHeight; y++) {
Color lColor = xBitmap.GetPixel(x, y);
bool lIsWhite = lColor.B == 255;
if (lIsWhite) {
if (lVector != null) {
lList.Add(lVector);
lVector = null;
}
}
else {
if (lVector == null) {
if (lXCoordinateOfFirstPixel < 0) lXCoordinateOfFirstPixel = x; // to always start at zero for our vectors
lVector = new Line { X = x - lXCoordinateOfFirstPixel, Y1 = y, Y2 = y };
}
else lVector.Y2 = y;
}
}
}
return lList;
} //
// The text was converted to vectors.
// Now we cut out the sequence we need for the display.
internal List<Line> getVectorSection(ref int xSectionFrom, ref int xSectionTo, float xEnd, float xWidth) {
int lCount = _TextAsVectorChain.Count;
float lStart = xEnd - xWidth;
// find the right section
do {
xSectionTo++;
if (xSectionTo >= lCount) { xSectionTo = lCount - 1; break; }
if (xEnd < _TextAsVectorChain[xSectionTo].X) break;
} while (true);
do {
if (lStart < 0) break; // to allow empty spaces at the beginning of the slogan
if (xSectionFrom >= lCount) return null;
if (lStart < _TextAsVectorChain[xSectionFrom].X) break;
xSectionFrom++;
} while (true);
// clone that section
List<Line> lList = new List<Line>();
for (int x = xSectionFrom; x <= xSectionTo; x++) {
Line lClone = _TextAsVectorChain[x].Clone();
lClone.X -= lStart; // adjust the X-axis
lList.Add(lClone);
}
return lList;
} //
} // class
} // namespace
namespace Ticker {
public class Line {
public float X { get; set; }
public float Y1 { get; set; }
public float Y2 { get; set; }
public Line Clone() {
Line lLine = new Line();
lLine.X = X;
lLine.Y1 = Y1;
lLine.Y2 = Y2;
return lLine;
} //
} // class
} // namespace
Clipboard to Text To Speech (TTS)
Since two years I am using Text To Speech (TTS). The quality has improved a lot. The spoken text can be understood and the pronunciations have reached good levels; not perfect though. Since Windows 7 there is no need to pay for a professional voice anymore. The Microsoft Windows system voices are sufficient.
First, I wanted to build my own add-on for the Firefox browser. But I quickly realised that there are too many constraints. I am using a nice tool on my Samsung Note 4 to listen to web site texts on a daily basis. That works out very well.
Nevertheless, this tool here is for home PCs.
ClipboardTTS monitors the windows clipboard and displays the current text in a WPF TextBox. In case the CheckBox “Auto” is checked the application starts speaking the text immediately. You can also generate WAV files. Adding this feature only took a few extra lines, otherwise it would not have been worth it. There are only a few use cases.
The Clipboard class offered in .Net does not provide events to monitor clipboard changes. We therefore have to use the old fashioned 32bit Windows functions. Therefore the codes section starts with imports from the windows “user32.dll”. With these you can subscribe to updates. The event WinProc notifies the application about changes. Most of these messages are disregarded in this application. We are only interested in two types of them. The first one is the Windows clipboard chain WM_CHANGECBCHAIN. You have to store the following window of the system clipboard chain, because we must forward messages to that one. This is a weird technology, but who knows what it is good for. For sure it simplifies suppressing messages without the need for any cancellation flag.
WM_DRAWCLIPBOARD is the other type we are interested in. This message tells you that the clipboard context has changed. Have a look at the C# code, you’ll quickly understand.
You could argue that the .Net Clipboard class is not needed, after all the user32.dll can do everything we need. Well, I think we should include as much .Net as possible. This is the right way to stick to the future.
Don’t forget to reference the System.Speech library in Visual Studio.
The application itself is pretty short. This is due to two facts. Windows is offering good SAPI voices and acceptable .Net support to use these voices.
http://msdn.microsoft.com/en-us/library/ee125077%28v=vs.85%29.aspx
I don’t see the point to implement an add-on for Firefox to follow the multi-platform approach. Do I have to re-invent the wheel? And check out the existing add-ons. You can hardly understand the spoken text. Some of these add-ons offer multi-language support. Yeah, but come on! You cannot understand a word. We are not in the 1990s anymore. Computers have learnt speaking very well. What is the language support good for if you cannot understand anything?
<Window x:Class="ClipboardTTS.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="ClipboardTTS" Height="140" Width="263"
Topmost="True"
Loaded="Window_Loaded"
Closed="Window_Closed">
<DockPanel LastChildFill="True">
<DockPanel DockPanel.Dock="Top" LastChildFill="False">
<CheckBox Name="Checkbox_OnOff" DockPanel.Dock="Left" Content="Auto" Margin="5" ToolTip="Speak as soon as the clipboard text changes"/>
<Button Content="Say it" DockPanel.Dock="Right" Click="Button_SayIt_Click" Width="50" Margin="5" ToolTip="Start/Stop speaking"/>
<Button Name="Button_Save" Content="Save" DockPanel.Dock="Right" Click="Button_Save_Click" Width="50" Margin="5" ToolTip="Create WAV sound file"/>
</DockPanel>
<ComboBox Name="ComboBox_Voices" DockPanel.Dock="Top" SelectionChanged="ComboBox_Voices_SelectionChanged" ToolTip="Voice"/>
<Slider Name="Slider_Volumne" DockPanel.Dock="Top" Minimum="0" Maximum="100" Value="50" ValueChanged="Slider_Volumne_ValueChanged" ToolTip="Volume" />
<TextBox Name="TextBox_Clipboard" TextChanged="TextBox_Clipboard_TextChanged" >
hello world !
</TextBox>
</DockPanel>
</Window>
using System;
using System.Collections.ObjectModel;
using System.Runtime.InteropServices;
using System.Speech.Synthesis;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Media;
namespace ClipboardTTS {
public partial class MainWindow : Window {
private const int WM_DRAWCLIPBOARD = 0x0308; // change notifications
private const int WM_CHANGECBCHAIN = 0x030D; // another window is removed from the clipboard viewer chain
private const int WM_CLIPBOARDUPDATE = 0x031D; // clipboard changed contents
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SetClipboardViewer(IntPtr xHWndNewViewer);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool ChangeClipboardChain(IntPtr xHWndRemove, IntPtr xHWndNewNext);
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SendMessage(IntPtr xHWnd, int xMessage, IntPtr xWParam, IntPtr xLParam);
private IntPtr _HWndNextViewer; // next window
private HwndSource _HWndSource; // this window
private string _Text = string.Empty;
private SpeechSynthesizer _SpeechSynthesizer = new SpeechSynthesizer();
public MainWindow() {
InitializeComponent();
} // constructor
private void StartListeningToClipboard() {
WindowInteropHelper lWindowInteropHelper = new WindowInteropHelper(this);
_HWndSource = HwndSource.FromHwnd(lWindowInteropHelper.Handle);
_HWndSource.AddHook(WinProc);
_HWndNextViewer = SetClipboardViewer(_HWndSource.Handle); // set this window as a viewer
} //
private void StopListeningToClipboard() {
ChangeClipboardChain(_HWndSource.Handle, _HWndNextViewer); // remove from cliboard viewer chain
_HWndNextViewer = IntPtr.Zero;
_HWndSource.RemoveHook(WinProc);
} //
private void SayIt(string xText) {
if (string.IsNullOrWhiteSpace(xText)) return;
_SpeechSynthesizer.Volume = (int)Slider_Volumne.Value;
_SpeechSynthesizer.SpeakAsync(xText);
} //
private IntPtr WinProc(IntPtr xHwnd, int xMessageType, IntPtr xWParam, IntPtr xLParam, ref bool xHandled) {
switch (xMessageType) {
case WM_CHANGECBCHAIN:
if (xWParam == _HWndNextViewer) _HWndNextViewer = xLParam;
else if (_HWndNextViewer != IntPtr.Zero) SendMessage(_HWndNextViewer, xMessageType, xWParam, xLParam);
break;
case WM_DRAWCLIPBOARD:
SendMessage(_HWndNextViewer, xMessageType, xWParam, xLParam);
processWinProcMessage();
break;
}
return IntPtr.Zero;
} //
private void processWinProcMessage() {
if (!Dispatcher.CheckAccess()) {
Dispatcher.Invoke(processWinProcMessage);
return;
}
if (!Clipboard.ContainsText()) return;
string lPreviousText = _Text;
_Text = Clipboard.GetText();
if (_Text.Equals(lPreviousText)) return; // do not play the same text again
InsertTextIntoTextBox(_Text);
if (Checkbox_OnOff.IsChecked.Value) SayIt(_Text);
} //
private void InsertTextIntoTextBox(string xText) {
if (!TextBox_Clipboard.Dispatcher.CheckAccess()) {
TextBox_Clipboard.Dispatcher.Invoke(() => InsertTextIntoTextBox(xText));
return;
}
TextBox_Clipboard.Text = xText;
} //
private void Button_SayIt_Click(object xSender, RoutedEventArgs e) {
if (_SpeechSynthesizer.State == SynthesizerState.Speaking) {
_SpeechSynthesizer.SpeakAsyncCancelAll();
return;
}
SayIt(TextBox_Clipboard.Text);
} //
private void TextBox_Clipboard_TextChanged(object xSender, System.Windows.Controls.TextChangedEventArgs e) {
_Text = TextBox_Clipboard.Text;
} //
private void Window_Loaded(object xSender, RoutedEventArgs e) {
ReadOnlyCollection<InstalledVoice> lVoices = _SpeechSynthesizer.GetInstalledVoices();
if (lVoices.Count < 1) return;
foreach (InstalledVoice xVoice in lVoices) {
ComboBox_Voices.Items.Add(xVoice.VoiceInfo.Name);
}
ComboBox_Voices.SelectedIndex = 0;
StartListeningToClipboard();
} //
private void Window_Closed(object xSender, EventArgs e) {
StopListeningToClipboard();
} //
private void ComboBox_Voices_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e) {
string xVoice = ComboBox_Voices.SelectedItem as string;
if (string.IsNullOrWhiteSpace(xVoice)) return;
_SpeechSynthesizer.SelectVoice(xVoice);
} //
private void Slider_Volumne_ValueChanged(object xSender, RoutedPropertyChangedEventArgs<double> e) {
_SpeechSynthesizer.Volume = (int)Slider_Volumne.Value;
} //
private Brush _OldButtonBrush = SystemColors.ControlBrush;
private void Button_Save_Click(object xSender, RoutedEventArgs e) {
_OldButtonBrush = Button_Save.Background;
Button_Save.Background = Brushes.Salmon;
Microsoft.Win32.SaveFileDialog lDialog = new Microsoft.Win32.SaveFileDialog();
string lPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
lDialog.InitialDirectory = lPath;
lDialog.FileOk += FileDialog_FileOk;
lDialog.Filter = "All Files|*.*|WAV (*.wav)|*.wav";
lDialog.FilterIndex = 2;
lDialog.ShowDialog();
} //
void FileDialog_FileOk(object xSender, System.ComponentModel.CancelEventArgs e) {
Microsoft.Win32.SaveFileDialog lDialog = xSender as Microsoft.Win32.SaveFileDialog;
if (lDialog == null) return;
if (!Dispatcher.CheckAccess()) {
Dispatcher.Invoke(() => FileDialog_FileOk(xSender, e));
return;
}
try {
string lPathAndFile = lDialog.FileName;
_SpeechSynthesizer.SetOutputToWaveFile(lPathAndFile);
_SpeechSynthesizer.SpeakCompleted += SpeechSynthesizer_SpeakCompleted;
SayIt(TextBox_Clipboard.Text);
Button_Save.Background = _OldButtonBrush;
}
catch (Exception ex) { MessageBox.Show(ex.Message); }
} //
void SpeechSynthesizer_SpeakCompleted(object sender, SpeakCompletedEventArgs e) {
_SpeechSynthesizer.SetOutputToDefaultAudioDevice();
_SpeechSynthesizer.SpeakCompleted -= SpeechSynthesizer_SpeakCompleted;
} //
} // class
} // namespace
Protocol Buffers (part 1, basics), follow-up to JSON & XML
I quickly introduced Protocol Buffers in my last post. It is an amazing tool that every programmer should know. The .Net version protobuf-net can be downloaded from here.
On its homepage Protocol Buffers is described with the following words:
Protocol buffers is the name of the binary serialization format used by Google for much of their data communications. It is designed to be:
small in size – efficient data storage (far smaller than xml)
cheap to process – both at the client and server
platform independent – portable between different programming architectures
extensible – to add new data to old messages
This is succinct. Protobuf-net also supports the WCF.
Add the protobuf-net.dll, which is located in the net30 installation directory, to your solution references.
We need some data structure to start with.
public class Book {
public string author;
public List<Fable> stories;
public DateTime edition;
public int pages;
public double price;
public bool isEbook;
} // class
public class Fable {
public string title;
public double[] customerRatings;
} // class
Protocol Buffers uses attributes to identify types to serialize. The ProtoMember attribute needs a positive integer. This can be painful, because you have to avoid overlapping when using inheritance. But integers have a distinct advantage as well. They are much faster than strings. As you are already aware, Protocol Buffers is about speed.
[ProtoContract]
public class Book {
[ProtoMember(1)]
public string author;
[ProtoMember(2)]
public List stories;
[ProtoMember(3)]
public DateTime edition;
[ProtoMember(4)]
public int pages;
[ProtoMember(5)]
public double price;
[ProtoMember(6)]
public bool isEbook;
public override string ToString() {
StringBuilder s = new StringBuilder();
s.Append("by "); s.Append(author);
s.Append(", edition "); s.Append(edition.ToString("dd MMM yyyy"));
s.Append(", pages "); s.Append(pages);
s.Append(", price "); s.Append(price);
s.Append(", isEbook "); s.Append(isEbook);
s.AppendLine();
if (stories != null) foreach (Fable lFable in stories) {
s.Append("title "); s.Append(lFable.title);
s.Append(", rating "); s.Append(lFable.customerRatings.Average());
s.AppendLine();
}
return s.ToString();
} //
} // class
[ProtoContract]
public class Fable {
[ProtoMember(1)]
public string title;
[ProtoMember(2)]
public double[] customerRatings;
} // class
public static Book GetData() {
return new Book {
author = "Aesop",
price = 1.99,
isEbook = false,
edition = new DateTime(1975, 03, 13),
pages = 203,
stories = new List<Fable>(new Fable[] {
new Fable{ title = "The Fox & the Grapes", customerRatings = new double[]{ 0.7, 0.7, 0.8} },
new Fable{ title = "The Goose that Laid the Golden Eggs", customerRatings = new double[]{ 0.6, 0.75, 0.5, 1.0} },
new Fable{ title = "The Cat & the Mice", customerRatings = new double[]{ 0.1, 0.0, 0.3} },
new Fable{ title = "The Mischievous Dog", customerRatings = new double[]{ 0.45, 0.5, 0.4, 0.0, 0.5} }
})
};
} //
Let’s serialize the data now.
public static void SerializeData() {
MemoryStream lStream = new MemoryStream();
BinaryWriter lWriter = new BinaryWriter(lStream); // no "using", because it would close the MemoryStream automatically
Book lBook = GetData();
ProtoBuf.Serializer.Serialize<Book>(lStream, lBook);
lWriter.Flush();
lStream.Position = 0;
using (BinaryReader lReader = new BinaryReader(lStream)) {
for (long i = 0, n = lStream.Length; i < n; i++) {
byte b = lReader.ReadByte();
Console.Write(string.Format("{0:X2} ", b));
if ((i+1) % 20 == 0) Console.WriteLine();
}
Console.WriteLine();
Console.WriteLine();
Console.WriteLine("number of bytes: " + lStream.Length);
}
Console.ReadLine();
} //
example output:
0A 05 41 65 73 6F 70 12 31 0A 14 54 68 65 20 46 6F 78 20 26
20 74 68 65 20 47 72 61 70 65 73 11 66 66 66 66 66 66 E6 3F
11 66 66 66 66 66 66 E6 3F 11 9A 99 99 99 99 99 E9 3F 12 49
0A 23 54 68 65 20 47 6F 6F 73 65 20 74 68 61 74 20 4C 61 69
64 20 74 68 65 20 47 6F 6C 64 65 6E 20 45 67 67 73 11 33 33
33 33 33 33 E3 3F 11 00 00 00 00 00 00 E8 3F 11 00 00 00 00
00 00 E0 3F 11 00 00 00 00 00 00 F0 3F 12 2F 0A 12 54 68 65
20 43 61 74 20 26 20 74 68 65 20 4D 69 63 65 11 9A 99 99 99
99 99 B9 3F 11 00 00 00 00 00 00 00 00 11 33 33 33 33 33 33
D3 3F 12 42 0A 13 54 68 65 20 4D 69 73 63 68 69 65 76 6F 75
73 20 44 6F 67 11 CD CC CC CC CC CC DC 3F 11 00 00 00 00 00
00 E0 3F 11 9A 99 99 99 99 99 D9 3F 11 00 00 00 00 00 00 00
00 11 00 00 00 00 00 00 E0 3F 1A 03 08 D2 1D 20 CB 01 29 D7
A3 70 3D 0A D7 FF 3Fnumber of bytes: 267
And back again: deserialize data.
public static void ToAndFro() {
using (MemoryStream lStream = new MemoryStream()) {
BinaryWriter lWriter = new BinaryWriter(lStream);
Book lBook = GetData();
ProtoBuf.Serializer.Serialize<Book>(lStream, lBook);
lWriter.Flush();
lStream.Position = 0;
Book lCopy = ProtoBuf.Serializer.Deserialize<Book>(lStream);
Console.WriteLine(lCopy.ToString());
}
Console.ReadLine();
} //
example output:
by Aesop, edition 13 Mar 1975, pages 203, price 1.99, isEbook False
title The Fox & the Grapes, rating 0.733333333333333
title The Goose that Laid the Golden Eggs, rating 0.7125
title The Cat & the Mice, rating 0.133333333333333
title The Mischievous Dog, rating 0.37
Async and await (advanced, .Net 4.5, C# 5)
The importance is in the details. It all looks easy, but follow each step carefully today.
Windows pauses threads that are waiting for I/O operations to complete (eg. internet or file access). The same threads cannot be used for other jobs in the meantime and new threads need to be created. You could use tasks to solve this specific problem. The program would start an asynchronous task to deal with an I/O operation. After a while the same task would trigger a follow-up procedure via continuation task. It requires some work to cover all code paths, but it can be done.
C# 5 has implemented new keywords to make your life easier. You can use async to mark methods for asynchronous operations, which start synchronously and then split up as soon as the program arrives at any await keyword.
The below Print() method prints the time, sequence and ThreadId. This information is useful to understand the program cycle.
private static void Print(int xStep) {
Console.WriteLine(DateTime.Now.ToString("HH:mm:ss") + " step " + xStep + " , thread " + Thread.CurrentThread.ManagedThreadId);
} //
static async void AsyncCalls1() {
Print(1);
int i = await Task.Run<int>(() => {
Print(2); Thread.Sleep(5000);
Print(3); return 0;
});
Print(4); // same thread as in step 3
Console.ReadLine();
// return void
} //
example output:
19:09:36 step 1 , thread 9
19:09:36 step 2 , thread 10
19:09:41 step 3 , thread 10
19:09:41 step 4 , thread 10
The above code is a warm up for us. The method AsyncCalls1() returns void. I emphasize this seemingly insignificant fact here. If you do not return void then the compiler will complain. It wants you to add async in the calling method as well. But if you do so, then it would also ask you to add async in the calling method, that called the calling method. It would be an endless game until you arrive at Main(). And there you would not know what to do, because you cannot use async in Main(). Novices can get quite frustrated with such minuscule glitch.
What is the program doing? It starts new task, which uses another thread from the thread pool. The original thread is then neglected, there is no follow-up. Now check this out: When the created task ends, the program continues with (Task.ContinueWith()) the same thread, which it was using in the task. It seems there is no context switching.
static async void AsyncCalls2() {
Print(1); Task<int> task = AsyncCalls3();
Print(4); int x = await task;
Print(7); // same thread as in step 6
Console.ReadLine();
// return void
} //
static async Task<int> AsyncCalls3() {
Print(2);
int i = await Task.Run<int>(() => {
Print(3); Thread.Sleep(5000);
Print(5); return 0;
});
Print(6); return i; // same thread as in step 5, returning an INTEGER !!!
} //
example output:
19:10:16 step 1 , thread 9
19:10:16 step 2 , thread 9
19:10:16 step 3 , thread 10
19:10:16 step 4 , thread 9
19:10:21 step 5 , thread 10
19:10:21 step 6 , thread 10
19:10:21 step 7 , thread 10
Method AsyncCalls3() has a return value, which is a Task. The task that is started inside this method returns an integer. But doesn’t Task.Run() have to return Task<int> according to its definition? It is the await that changes the behavior. It returns the integer value (0). await has been implemented to shorten code, and this is what it does. The code is more legible.
Method AsyncCalls2() calls AsyncCalls3() and receives an integer and not a Task<int>. This is caused by the async keyword.
AsyncCalls2() itself returns void. This is the same issue as with AsyncCalls1(). However AsyncCalls3() can return a value to AsyncCalls2(), because AsyncCalls2() itself uses the async keyword in the method definition.
Check the program sequence. I marked the steps clearly to make comprehension easy. And then analyse the thread context switching. Between step 2 and 3 is a context switch operation, but not between 5, 6 and 7. This is the same behavior as in the first example code.
public static async void AsyncCalls4() {
Print(1); string s = await AsyncCalls5();
Print(4);
Console.ReadLine();
// return void
} //
// using System.Net.Http;
public static async Task<string> AsyncCalls5() {
using (HttpClient lClient = new HttpClient()) {
Print(2); string lResult = await lClient.GetStringAsync("http://www.microsoft.com");
Print(3); return lResult;
}
} //
example output:
19:11:47 step 1 , thread 10
19:11:47 step 2 , thread 10
19:11:48 step 3 , thread 14
19:11:48 step 4 , thread 14
When searching for async and await on the web you will find the emphasis on I/O. Most example programs concentrate on this and don’t explain what is roughly going on inside the async-I/O method itself. Basically .Net async-I/O methods deal with tasks and use a similar construction to Task.ContinueWith(). This is why I concentrated on different examples that can be used in any context (even though not very meaningful examples). The internet download example is more or less a classical one. You can use await on many I/O methods. Keep in mind that AsyncCalls4() returns void and that you are not supposed to call AsyncCalls5() from the Main() method, because you would have to add async to it.
C# Hardcore Programming 