Problems with rendering text as bitmaps using WPF - wpf

Question

I am developing an application using WPF to dynamically render content, including text and images from WPF into jpg files. I am currently using the RenderTargetBitmap class to do the job. Everything works as expected but the quality of the rendered fonts is terrible. I understand that the RenderTargetBitmap doesn’t use the ClearType but a GrayScale antialias, which is kind of blury with small fonts. But I am using large fonts, larger than 30 pts, and the results are totally unacceptable. Is there some kind of workaround for this issue?
[Update]
The Code I am using is listed below. As expected it is called on each Rendering event of the CompositionTarget.
void CompositionTarget_Rendering(object sender, EventArgs e)
{
prefix = "";
if (counter < 10)
{
prefix = "000";
}
else if (counter < 100)
{
prefix = "00";
}
else if (counter < 1000)
{
prefix = "0";
}
Size size = new Size(MainCanvas.Width, MainCanvas.Height);
MainCanvas.Measure(size);
MainCanvas.Arrange(new Rect(size));
RenderTargetBitmap bmp = new RenderTargetBitmap(imgWidth, imgHeight, 96d, 96d, PixelFormats.Default);
bmp.Render(MainCanvas);
JpegBitmapEncoder encoder = new JpegBitmapEncoder();
encoder.QualityLevel = 90;
encoder.Frames.Add(BitmapFrame.Create(bmp));
string file = basePath + prefix + counter.ToString() + "_testpic.jpg";
using (Stream stm = File.Create(file))
{
encoder.Save(stm);
}
counter++;
}
Here are some examples of the resulting images:
alt text http://www.randomnoise.org/temp/testpic_v1.jpg
alt text http://www.randomnoise.org/temp/testpic_v2.jpg
Thanks in advance.

Answer 1

Try this:
int height = (int)border.ActualHeight;
int width = (int)border.ActualWidth;
RenderTargetBitmap bmp = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Pbgra32);
bmp.Render(border);
border being what you're trying to save as bitmap.

Answer 2

Ok, I finally found a solution. Gustavo you were on the right track. The problem was that the main container that I was trying to render as bitmap was being distorted by its parent container. The solution was to add the main container to a canvas, that doesn't have a layout engine that distorts its children. I still need to do some more experimenting but it looks very promising. Apparently RenderTargetBitmap doesn't like distorted fonts at all.