I've got a fancy looking chart control I've written, and people will use it to generate plots for Powerpoint presentations, so I need to be able to copy the plots to some fixed size like say 1024x768.
Say I have a button "Copy Plot To Bitmap". Ok my code will look like this:
private BitmapSource RenderToBitmap(double width, double height){
double baseHeight = this.ActualHeight; double baseWidth = this.ActualWidth; this.LayoutTransform = new ScaleTransform(baseWidth/width, baseHeight/height); RenderTargetBitmap rtb = new RenderTargetBitmap(width, height, 96d*width/baseWidth, 96d*height/baseHeight, PixelFormats.Default);rtb.Render(
this); BmpBitmapEncoder encoder = new BmpBitmapEncoder();encoder.Frames.Add(
BitmapFrame.Create(rtb)); FileStream fs = File.Open(@"c:\test.bmp", FileMode.Create);encoder.Save(fs);
fs.Close();
this.LayoutTransform = new ScaleTransform(1, 1); return rtb;}
the problem is, is that the Transform isn't applied until later. So I guess I need to set the tranform, wait until it is rendered, and then copy it to the bitmap. Or is there a better way that someone has come up with
What's a good way to Render to a bitmap that is a different size to the Visual?
Ralph Rivas
Saqib Ullah
Bigger or smaller, and with a different aspect ratio. But I have it all worked out now. I wanted to change the size of the image, but retain the font size of any text I wanted rendered. I just wasn't aware of the UpdateTranform () method. There's a lot of stuff to discover in this new WPF stuff.
Andy Lambert
Got the solution!
After I set the LayoutTransform I need to call
this.UpdateLayout();
Adding that enables you to make the above code render any visual to any size bitmap and save it to disk.
Dorian A
Am I getting this right You're tryin to fit a bigger image into a smaller image"box"
RobertPalmer
to render just part of an image, try using an ImageBrush and its Viewbox property. the following code sample will render the chunk of the image from 33% to 66% in the horizontal direction and from 25% to 75% in the vertical direction.
you can also add ViewboxUnits="Absolute" to the ImageBrush and work in terms of pixels instead of percentages.
<Rectangle x:Name="image" Margin="0,0,3,0" RadiusX="5" RadiusY="5" HorizontalAlignment="Left" VerticalAlignment="Top" Width="40" Height="40"> <Rectangle.Fill> <ImageBrush AlignmentX="Left" AlignmentY="Center" TileMode="None" Stretch="Uniform" Viewbox="0.3333,0.25,0.3333,0.50" ImageSource="myimage.jpg"/> </Rectangle.Fill> </Rectangle>devdept