Convert a Canvas into an Image

Hi,
I have once faced this problem and google produced me with pieces of information which i grouped into the following. The below function will take a Canvas element as an input and makes an image out of it.

public static BitmapDecoder CreateImageFromCanvas(UIElement element, int dpix, int dpiy, ImageFormat format)
{
double dpiX = 96;
double dpiY = 96;

FrameworkElement fwElement = element as FrameworkElement;
Rect bounds = VisualTreeHelper.GetContentBounds(fwElement);
bounds = new Rect(0, 0, fwElement.Width, fwElement.Height);

// create the renderer.
RenderTargetBitmap rendertarget = new RenderTargetBitmap((Int32)(bounds.Width * dpiX/96.0),
(Int32)(bounds.Height*dpiY / 96.0), dpiX, dpiY, PixelFormats.Pbgra32);
// Render the element on screen.
rendertarget.Render(element);

BitmapEncoder bmpe;

// Select the image format.
if (format == ImageFormat.Png)
{
bmpe = new PngBitmapEncoder();
}
else if (format == ImageFormat.Bmp)
{
bmpe = new BmpBitmapEncoder();
}
else if (format == ImageFormat.Jpeg)
{
bmpe = new JpegBitmapEncoder();
}
else
{
bmpe = new PngBitmapEncoder();
}

bmpe.Frames.Add(BitmapFrame.Create(rendertarget));

Stream fl = new MemoryStream();
bmpe.Save(fl);


BitmapDecoder bmpd;
// Select the image format.
if (format == ImageFormat.Png)
{
bmpd = new PngBitmapDecoder(fl, BitmapCreateOptions.IgnoreColorProfile, BitmapCacheOption.Default);
}
else if (format == ImageFormat.Bmp)
{
bmpd = new BmpBitmapDecoder(fl, BitmapCreateOptions.IgnoreColorProfile, BitmapCacheOption.Default);
}
else if (format == ImageFormat.Jpeg)
{
bmpd = new JpegBitmapDecoder(fl, BitmapCreateOptions.IgnoreColorProfile, BitmapCacheOption.Default);
}
else
{
bmpd = new PngBitmapDecoder(fl, BitmapCreateOptions.IgnoreColorProfile, BitmapCacheOption.Default);
}

MemoryStream mStream = (MemoryStream)fl;
System.IO.File.WriteAllBytes("F:\\Samples\\myimage."+format, mStream.ToArray());

fl.Close();

return bmpd;
}

Remember you can only pass a canvas element as an argument to this function. Ofcourse it accepts any UIElement but if you pass anything other than a Canvas element you will get a blank image.

Subsequently you can use this function in your main class file like,
myImage.Source = GrapSnapShot(myCanvas, 89,89,ImageFormat.Png).Frames[0];
where myImage is an Image element in your xaml file and it displays your canvas as an image.

Difference between Logical and Visual Tree in WPf

Hi All,
Just go through this link:

http://blogs.msdn.com/mikehillberg/archive/2008/05/23/Of-logical-and-visual-trees-in-WPF.aspx