[gobler]

ViewerSvg has a feature to export a Canvas as a PNG file. I expected an equivalent method to be available on ReaderSvg, but I do not see one.

When I use the Export Image feature in ViewerSvg, the resulting bitmap is much smaller than what's rendered in the view. Is there a way to control this?

Thanks.

[abenedik]

Rendering any WPF Visual element can be done with WPF's RenderTargetBitmap.

The following two methods can be used to render the element to a bitmap and to save the image to disk.

Code:

public static BitmapSource RenderImage(FrameworkElement objectToRender, int width, int height, Brush backgroundBrush)
        {
            Rectangle backgroundRect = null;

            // If the object was not measured and arranged yet we need to do this before rendering
            if (objectToRender.ActualWidth == 0)
            {
                objectToRender.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
                objectToRender.Arrange(new Rect(new Point(0, 0), objectToRender.DesiredSize));
            }

            if (backgroundBrush != null)
            {
                backgroundRect = new Rectangle();
                backgroundRect.Width = width;
                backgroundRect.Height = height;
                backgroundRect.Fill = backgroundBrush;
                backgroundRect.Arrange(new Rect(0, 0, width, backgroundRect.Height));
            }

            RenderTargetBitmap bitmap = new RenderTargetBitmap(width, height, 96, 96 /* standard WPF dpi setting 96 */, PixelFormats.Pbgra32);

            if (backgroundRect != null)
                bitmap.Render(backgroundRect);

            bitmap.Render(objectToRender);

            return bitmap;
        }

        public static void SaveImage(BitmapSource image, string resulImageFileName)
        {
            // write the bitmap to a file
            using (System.IO.FileStream fs = new System.IO.FileStream(resulImageFileName, System.IO.FileMode.Create))
            {
                BitmapEncoder enc;

                if (resulImageFileName.EndsWith("jpg"))
                    enc = new JpegBitmapEncoder();
                else if (resulImageFileName.EndsWith("tif") || resulImageFileName.EndsWith("tiff"))
                    enc = new TiffBitmapEncoder();
                else
                    enc = new PngBitmapEncoder();

                BitmapFrame bitmapImage = BitmapFrame.Create(image);
                enc.Frames.Add(bitmapImage);
                enc.Save(fs);
            }
        }

Note that the width and height that are passed to RenderImage method do not scale the element to be that size - its ActualWidtha and ActualHeight is used in the output image.

To render the element to a custom size a VisualBrush can be used - check the following: http://stackoverflow.com/questions/22275...-to-bitmap