Discorax's House of w00t

Have you ever wanted to get the Bitmap Data (pixels) of a Visual (Canvas, Grid, etc) in WPF or Silverlight from memory and without having to add it to the root visual. After doing a lot of trial and error here is a quick piece of code and a sample project that can help you accomplish exactly that.

There are plenty of cool ways to extend this project including some cool transition and other code based animations. Just let your imagination go wild!

First, create a new WPF Application in Visual Studio or [download a sample project]. In your Window1.xaml give the Grid an x:Name value. You'll use this to add your elements later on.
<br /><Grid x:Name="VisualRoot"></Grid><br />

Now lets add a new Page to our project. We're going to alter the Page to extend a Canvas rather than a Page for no other reason then when I'm creating animations I prefer to work with a Canvas. We are going to put some visuals onto our canvas. In the sample it's a blue square with a red circle next to it and a little bit of text below it. It could be any UIElement including another Canvas/Grid, Images, Text anything.

In our Window1.xaml code behind we're going to create an instance of our Canvas1 and call the methods to have WPF Measure, Arrange, and UpdateLayout in memory. We need to call these methods in order for WPF to figure out where all the pixels are positioned in our visual to return accurate Bitmap Data. These methods are called automatically when you add a Visual to WPF using the Visual.Children.Add() method.

The CreateBitmapSourceFromVisual function was taken from a project on CodePlex, unfortunately I can't recall the link. I'll add it here if I run across it again. That function takes a Visual and returns a BitmapSource object with the pixel data. It automatically updates the dots per inch (DPI) to 96, which is required for WPF to render properly).

Here is the code behind from our root Window.

<br />using System;<br />using System.Collections.Generic;<br />using System.Linq;<br />using System.Text;<br />using System.Windows;<br />using System.Windows.Controls;<br />using System.Windows.Data;<br />using System.Windows.Documents;<br />using System.Windows.Input;<br />using System.Windows.Media;<br />using System.Windows.Media.Imaging;<br />using System.Windows.Navigation;<br />using System.Windows.Shapes;<br /><br />namespace BitmapFromVisualSample<br />{<br /> /// <summary><br /> /// Interaction logic for Window1.xaml<br /> /// </summary><br /> public partial class Window1 : Window<br /> {<br /> public Window1()<br /> {<br /> InitializeComponent();<br /> Canvas1 myVisualElement = new Canvas1();<br /> myVisualElement.Measure(new System.Windows.Size(0, 0));<br /> myVisualElement.Arrange(new Rect(new System.Windows.Size(0, 0)));<br /> myVisualElement.UpdateLayout();<br /> // Note the myVisualElement is never added<br /><br /> // Use myVisualElement to get our Bitmap Source Data.<br /> BitmapSource myVisualElementBitmapData = CreateBitmapSourceFromVisual(300, 500, myVisualElement, false);<br /> // Create an Image for your Bitmap Source<br /> Image myImage = new Image();<br /> // use our Bitmap Data <br /> myImage.Source = myVisualElementBitmapData;<br /><br /> // Add our Image to the Grid<br /> VisualRoot.Children.Add(myImage);<br /> }<br /> public BitmapSource CreateBitmapSourceFromVisual(Double width, Double height, Visual visualToRender, Boolean undoTransformation)<br /> {<br /> if (visualToRender == null)<br /> {<br /> return null;<br /> }<br /> RenderTargetBitmap bmp = new RenderTargetBitmap(<br /> (Int32)Math.Ceiling(width),<br /> (Int32)Math.Ceiling(height),<br /> 96,<br /> 96,<br /> PixelFormats.Pbgra32);<br /> if (undoTransformation)<br /> {<br /> DrawingVisual dv = new DrawingVisual();<br /> using (DrawingContext dc = dv.RenderOpen())<br /> {<br /> VisualBrush vb = new VisualBrush(visualToRender);<br /> System.Windows.Point myPoint = new System.Windows.Point();<br /> dc.DrawRectangle(vb, null, new Rect(myPoint, new System.Windows.Size(width, height)));<br /> }<br /> bmp.Render(dv);<br /> }<br /> else<br /> {<br /> bmp.Render(visualToRender);<br /> }<br /> return bmp;<br /> <br /> }<br /> }<br />}<br /><br />



You can run the sample project and you will see the visual we created in Canvas1. We used the BitmapSource object of the Canvas1 as the Source of our Image. Note: we never added Canvas1 to the root visual, we simply created it in the code behind and retrieved the pixel data from that visual to use as on our Image. I leave it to you to play with this technology to create cool WPF/Silverlight animations.

[Download Source Code] as Visual Studio Project.

Labels: C#, Silverlight, WPF

The more I learn Object Oriented Programing techniques the more I value the ability to have my classes listen to each other. I've been working in C# a lot recently for a WPF project. At various points throughout the development process I've found a need to have different events cause effects among objects and classes. .NET has a great list of events built into many of their classes especially the UIElements and Controls. What I want to do is put together some code snippets on how to build a custom event for your object and hopefully to help some new C# programmers better understand how events work and how powerful they can be.

<br />using System;<br />using System.Collections.Generic;<br />using System.Linq;<br />using System.Text;<br />using System.Windows;<br />using System.Windows.Controls;<br />using System.Windows.Data;<br />using System.Windows.Documents;<br />using System.Windows.Input;<br />using System.Windows.Media;<br />using System.Windows.Media.Imaging;<br />using System.Windows.Navigation;<br />using System.Windows.Shapes;<br /><br />namespace CustomEventExample<br />{<br /><br /> public partial class Window1 : Window<br /> {<br /> <br /> public Window1()<br /> {<br /> InitializeComponent();<br /> EventBroadcasterClass eventClass = new EventBroadcasterClass();<br /> <br /> }<br /> }<br /><br /> public class EventBroadcasterClass <br /> {<br /> public event CustomEvent myEvent;<br /> protected virtual void MyEventMethod(CustomEventArgs e)<br /> {<br /> if (myEvent != null)<br /> {<br /> //invoke the delegates<br /> myEvent(this, e);<br /> }<br /> }<br /> public EventBroadcasterClass()<br /> {<br /> // Create a new CustomEventHandler Object<br /> CustomEventHandler myEventHandler = new CustomEventHandler();<br /> // Add the Handle method as a listener to the myEvent Event <br /> this.myEvent += new CustomEvent(myEventHandler.Handle);<br /> // Create some custom event args<br /> CustomEventArgs e = new CustomEventArgs("Text from EventBroadcasterClass");<br /> // Call the CustomEventMethod passing the EventArgs<br /> MyEventMethod(e);<br /> }<br /> <br /> }<br /> public class CustomEventHandler<br /> {<br /> public string myString;<br /> // The Handle Method is what is listening for myEvent to be broadcast<br /> public void Handle(object sender, CustomEventArgs e)<br /> {<br /> // You can get information passed in the CustomEventArgs <br /> // We've set it up to pass a string through the property MyString<br /> myString = e.MyString;<br /> // Put it all together in the Console<br /> Console.WriteLine("{0} {1}", myString, "displayed by CustomEventHandler Method");<br /> <br /> }<br /> }<br /> // You can pass all kinds of different data through CustomEventArgs<br /> // You just need to set up the Object accordingly<br /> public class CustomEventArgs : EventArgs<br /> {<br /> private readonly string myString;<br /> public CustomEventArgs(string myString)<br /> {<br /> this.myString = myString;<br /> }<br /> // This is the public property within your Event Args<br /> public string MyString { get { return myString; } }<br /> }<br /> // Create a CustomEvent delegate which will relay your event to all the Listeners<br /> public delegate void CustomEvent(object sender, CustomEventArgs e);<br /><br /><br />}<br /><br />

What in the world does that do you ask...well lets break it down.

The first part of this example is based on a WPF Application template from Visual Studio 2008. It includes all the using statements, the namespace deceleration and the Window1 class. The reason I included all this is so that you can download the Project file and poke around.

Inside the Window1 constructor we're going to create an instance of our EventBroadcasterClass so that we can use it to send out our custom event.

<br />EventBroadcasterClass eventClass = new EventBroadcasterClass();<br />

The EventBroadcasterClass has a public event myEvent and a Method to broadcast it, MyEventMethod. The constructor method then creates a new CustomEventHandler Object myEventHandler and adds it's Handle method as a listener to the EventBroadcasterClass myEvent event.

You can pass a variety of data through events (although it's not always the best approach). In this case we set up a new CustomEventArgs object and added some text to it. "Text from EventBroadcasterClass" will be used by our CustomEventHandler later on. Here is the whole EventBroadcasterClass.

<br />public class EventBroadcasterClass <br /> {<br /> public event CustomEvent myEvent;<br /> protected virtual void MyEventMethod(CustomEventArgs e)<br /> {<br /> if (myEvent != null)<br /> {<br /> //invoke the delegates<br /> myEvent(this, e);<br /> }<br /> }<br /> public EventBroadcasterClass()<br /> {<br /> // Create a new CustomEventHandler Object<br /> CustomEventHandler myEventHandler = new CustomEventHandler();<br /> // Add the Handle method as a listener to the myEvent Event <br /> this.myEvent += new CustomEvent(myEventHandler.Handle);<br /> // Create some custom event args<br /> CustomEventArgs e = new CustomEventArgs("Text from EventBroadcasterClass");<br /> // Call the CustomEventMethod passing the EventArgs<br /> MyEventMethod(e);<br /> }<br /> <br /> }<br />

The CustomEventHandler is very simple. It has a string property and a Handle method. As you can see the Handle method takes two arguments. object sender is where the event was broadcast from, in this case it's the EventBroadcasterClass, and a CustomEventArgs object. This is where the string value we set in our broadcaster is held. To access it we just have to set our string property to the CustomEventArgs public property MyString. Then all we do is write it out to the Console for demonstration purposes. Here is the CustomEventHandler Class

<br />public class CustomEventHandler<br /> {<br /> public string myString;<br /> // The Handle Method is what is listening for myEvent to be broadcast<br /> public void Handle(object sender, CustomEventArgs e)<br /> {<br /> // You can get information passed in the CustomEventArgs <br /> // We've set it up to pass a string through the property MyString<br /> myString = e.MyString;<br /> // Put it all together in the Console<br /> Console.WriteLine("{0} {1}", myString, "displayed by CustomEventHandler Method");<br /> <br /> }<br /> }<br />

The final piece of this puzzle is the CustomEventArgs. This Class just hold the arguments we pass between events and listeners. You can fill this object will anything, although it can really hurt performance if you pass too much data in event args. The constructor method sets a private property and the public MyString property which has a get to return the value set when the CustomEventArgs object is created. Directly below we see a public delegate CustomEvent. This delegate is used to relay your event to any object that is listening.


<br />// You can pass all kinds of different data through CustomEventArgs<br /> // You just need to set up the Object accordingly<br /> public class CustomEventArgs : EventArgs<br /> {<br /> private readonly string myString;<br /> public CustomEventArgs(string myString)<br /> {<br /> this.myString = myString;<br /> }<br /> // This is the public property within your Event Args<br /> public string MyString { get { return myString; } }<br /> }<br /> // Create a CustomEvent delegate which will relay your event to all the Listeners<br /> public delegate void CustomEvent(object sender, CustomEventArgs e);<br /><br /><br />}<br /><br />

It took me some time to put all these pieces together, but now that I have I can build Classes that are always aware of what others are doing, which can have some very cool effects. I hope this little summary will help others get up to speed quickly building Custom Events in C#.

Download the Source Code

Labels: C#, WPF

At more than one time working with WPF I've wanted to create a generic Storyboard using Blend because it saves me time and gives me a nice time line type layout to create/tweak my Storyboard. What happens is when you save the Storyboard it's added to the Windows.Resources collection the XAML. In Silverlight you can access these Storyboard resources directly using their x:Name value. In WPF, however, you need to do it slightly differently.

• First, You need to specify x:Key for each Storyboard


• Storyboards must be found using TryFindResource:
  
  Storyboard myStoryboard = (Storyboard)TryFindResource("myStoryboard");


• TryFindResource will only work if the Storyboard is in the Window.Resources section of the XAML and you're in the code-behind of that XAML


• Once you have the reference to the Storyboard contained in a variable you can call the various Storyboard methods on it. To run it, use the Begin method:
  
  myStoryboard.Begin();

Here is a quick code snippet to help you out.

<br /><br />using System;<br />using System.Collections.Generic;<br />using System.Linq;<br />using System.Text;<br />using System.Windows;<br />using System.Windows.Controls;<br />using System.Windows.Data;<br />using System.Windows.Documents;<br />using System.Windows.Input;<br />using System.Windows.Media;<br />using System.Windows.Media.Imaging;<br />using System.Windows.Shapes;<br />using System.Media.Animation;<br />using System.Windows.Resources;<br />using System.Windows.Markup;<br />// Make sure to include this reference to use Storyboard Class<br />using System.Windows.Media.Animation;<br /><br /><br />namespace StoryboardSample<br />{<br /> public partial class Window1 : Window<br /> {<br /> // Set up the Storyboard variable<br /> public Storyboard myStoryboard;<br /> public Window1()<br /> {<br /> this.InitializeComponent();<br /> <br /> // Assign the Storyboard to the variable.<br /> myStoryboard = (Storyboard)TryFindResource("myStoryboard");<br /> myFunction();<br /> <br /> }<br /> public void myFunction()<br /> {<br /> // Begin the Animation<br /> myStoryboard.Begin();<br /> }<br /> }<br />}<br /><br />

Here is the XAML:

<br /><Window<br /> xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"<br /> xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"<br /> x:Class="StoryboardSample.Window1"<br /> x:Name="Window"<br /> Title="Window1"<br /> Width="640" Height="480"><br /> <Window.Resources><br /> <Storyboard x:Key="myStoryboard"><br /> <DoubleAnimationUsingKeyFrames BeginTime="00:00:00" Storyboard.TargetName="myRect" Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[3].(TranslateTransform.Y)"><br /> <SplineDoubleKeyFrame KeyTime="00:00:00" Value="0"/><br /> <SplineDoubleKeyFrame KeyTime="00:00:01" Value="-71"/><br /> </DoubleAnimationUsingKeyFrames><br /> </Storyboard><br /> </Window.Resources><br /> <Grid x:Name="LayoutRoot"><br /> <Rectangle x:Name="myRect" Fill="Black" Width="300" Height="150" RenderTransformOrigin="0.5,0.5" ><br /> <Rectangle.RenderTransform><br /> <TransformGroup><br /> <ScaleTransform ScaleX="1" ScaleY="1"/><br /> <SkewTransform AngleX="0" AngleY="0"/><br /> <RotateTransform Angle="0"/><br /> <TranslateTransform X="0" Y="0"/><br /> </TransformGroup><br /> </Rectangle.RenderTransform><br /> </Rectangle><br /> </Grid><br /></Window><br />

Labels: C#, WPF, XAML

I've been working on a cool instillation project for Microsoft and one of the things I need to do is have my application go full screen across multiple monitors. By default, if you maximize your application window inside Windows it fills the Primary Screen or Active screen but it doesn't go across all monitors. You have to manually drag the application window across to have it show up on more than one monitor. What if you wanted to make a screen saver for multiple monitors? Doing some internet searching I pieced together this little solution. Here is a code snippet that maximizes your WPF app window across all monitors in multi-mon setups. It also adds a listener for the ESC key to close the window down. Hope this helps people find this solution faster in the future.

<br />using System;<br />using System.Collections.Generic;<br />using System.Linq;<br />using System.Text;<br />using System.Windows;<br />using System.Windows.Interop;<br />using System.Runtime.InteropServices;<br />using System.Windows.Controls;<br />using System.Windows.Data;<br />using System.Windows.Documents;<br />using System.Windows.Input;<br />using System.Windows.Media;<br />using System.Windows.Media.Imaging;<br />using System.Windows.Navigation;<br />using System.Windows.Shapes;<br />using System.Windows.Forms;<br /><br />namespace MyNamespace<br />{<br /> /// <summary><br /> /// Maximize your WPF app window across multiple monitors logic for Window1.xaml<br /> /// Also ads the ESCAPE key to close the window.<br /> /// </summary><br /> public partial class Window1 : Window<br /> {<br /> int height = 0;<br /> int width = 0;<br /><br /> public Window1()<br /> {<br /> <br /> InitializeComponent();<br /> <br /><br /> foreach (System.Windows.Forms.Screen screen in System.Windows.Forms.Screen.AllScreens)<br /> {<br /> // height += screen.WorkingArea.Height; <-- Changed this line<br /> // If you want to make sure your largest screen height is used<br /> // put some logic in here to check the value of height against<br /> // screen.WorkingArea.Height in the foreach loop. <br /> // otherwise the value of height will be the rightmost screen<br /> // in your system setup.<br /> height = screen.WorkingArea.Height;<br /> width += screen.WorkingArea.Width;<br /><br /> }<br /><br /> Top = 0;<br /> Left = 0;<br /> this.Height = height;<br /> this.Width = width;<br /><br /><br /> <br /> this.WindowState = WindowState.Normal;<br /> this.WindowStyle = WindowStyle.None;<br /> this.ResizeMode = ResizeMode.NoResize;<br /> <br /> this.KeyDown += new System.Windows.Input.KeyEventHandler(Window1_KeyDown);<br /> }<br /><br /> void Window1_KeyDown(object sender, System.Windows.Input.KeyEventArgs e)<br /> {<br /> if (e.Key == System.Windows.Input.Key.Escape)<br /> this.Close();<br /> }<br /> }<br />}<br /><br />

Then in your XAML make sure you don't have any values set so the code behind can do it's thing.
<br /><Window x:Class="MyNamespace.Window1"<br /> xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"<br /> xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"<br /> Title="Window1" ><br />

Labels: C#, WPF