I've got an app that turns some XAML Usercontrols into PNGs - this has worked really well up to now, unfortunately I now need to double the size of the images.
My method (that doesn't work!) was to add a ScaleTransform to the visual element after I've loaded it ...
This line is the new line at the top of the SaveUsingEncoder method.
visual.RenderTransform = GetScaleTransform(2);
The PNG is the new size (3000 x 2000) - but the XAML is Rendered at 1500x1000 in the centre of the image.
Can anyone assist please?
private void Load(string filename)
{
var stream = new FileStream(filename), FileMode.Open);
var frameworkElement = (FrameworkElement)(XamlReader.Load(stream));
var scale = 2;
var encoder = new PngBitmapEncoder();
var availableSize = new Size(1500 * scale, 1000 * scale);
frameworkElement.Measure(availableSize);
frameworkElement.Arrange(new Rect(availableSize));
name = name.Replace(" ", "-");
SaveUsingEncoder(frameworkElement, string.Format(@"{0}.png", name), encoder, availableSize);
}
private TransformGroup GetScaleTransform(int scale)
{
var myScaleTransform = new ScaleTransform {ScaleY = scale, ScaleX = scale};
var myTransformGroup = new TransformGroup();
myTransformGroup.Children.Add(myScaleTransform);
return myTransformGroup;
}
private void SaveUsingEncoder(FrameworkElement visual, string fileName, BitmapEncoder encoder, Size size)
{
visual.RenderTransform = GetScaleTransform(2);
var bitmap = new RenderTargetBitmap(
(int) size.Width,
(int) size.Height,
96,
96,
PixelFormats.Pbgra32);
bitmap.Render(visual);
var frame = BitmapFrame.Create(bitmap);
encoder.Frames.Add(frame);
using (var stream = File.Create(fileName))
{
encoder.Save(stream);
}
}
Called visual.UpdateLayout before rendering into the RenderTargetBitmap
(Thanks to Clemens for this answer - but he put it as a comment!)