Take screenshot of wpf popup window

Question

I try to take a screenshot of an application writen in WPF and the application is not captured, must I use a special tool to take the screenshot?

Answer 1

You can use RenderTargetBitmap to generate an image from your WPF control.

    public const int IMAGE_DPI = 96;

    public Image GenerateImage(T control)
        where T : Control, new()
    {
        Size size = RetrieveDesiredSize(control);

        Rect rect = new Rect(0, 0, size.Width, size.Height);

        RenderTargetBitmap rtb = new RenderTargetBitmap((int)size.Width, (int)size.Height, IMAGE_DPI, IMAGE_DPI, PixelFormats.Pbgra32);

        control.Arrange(rect); //Let the control arrange itself inside your Rectangle
        rtb.Render(control); //Render the control on the RenderTargetBitmap

        //Now encode and convert to a gdi+ Image object
        PngBitmapEncoder png = new PngBitmapEncoder();
        png.Frames.Add(BitmapFrame.Create(rtb));
        using (MemoryStream stream = new MemoryStream())
        {
            png.Save(stream);
            return Image.FromStream(stream);
        }
    }

    private Size RetrieveDesiredSize(T control)
    {
        if (Equals(control.Width, double.NaN) || Equals(control.Height, double.NaN))
        {
            //Make sure the control has measured first:
            control.Measure(new Size(double.MaxValue, double.MaxValue));

            return control.DesiredSize;
        }

        return new Size(control.Width, control.Height);
    }

Note that this will generate a PNG image ;) If you wish to store it as a JPEG, I suggest you use another encoder :)

Image image = GenerateImage(gridControl);
image.Save("mygrid.png");