Getting Image from UIElement is cropped to displayed size

Question

I am taking an image of a wpf control using this code:

BitmapEncoder imgEncoder = new PngBitmapEncoder();
RenderTargetBitmap bmpSource = new RenderTargetBitmap((int)element.ActualWidth, (int)element.ActualHeight, 150, 150, PixelFormats.Pbgra32);
bmpSource.Render(element);
imgEncoder.Frames.Add(BitmapFrame.Create(bmpSource));
using (MemoryStream ms = new MemoryStream())
{
    imgEncoder.Save(ms);
    bytes = ms.ToArray();
    ms.Position = 0;
    Image i = Image.FromStream(ms);
    i.Save(@"C:\" + Guid.NewGuid().ToString() + "LARGE.png");
}

The trouble is ActualHeight/Width property gives the rendered height and width i.e. the displayed part. I want to save an image of the whole control even if some of the control is not visible on the screen i.e. it is placed in a scrollviewer.

How can I get the full size / height of a control so the bmpSource.Render() renders the whole control to an image?

score 1 · Answer 1 · answered Nov 15 '11 at 11:50

     private static void SaveUsingEncoder(string fileName, FrameworkElement UIElement, BitmapEncoder encoder)
    {
        int height = (int)UIElement.ActualHeight;
        int width = (int)UIElement.ActualWidth;

        // These two line of code make sure that you get completed visual bitmap.
        // In case your Framework Element is inside the scroll viewer then some part which is not
        // visible gets clip.  
        UIElement.Measure(new System.Windows.Size(width, height));
        UIElement.Arrange(new Rect(new System.Windows.Point(), new Point(width, height)));

        RenderTargetBitmap bitmap = new RenderTargetBitmap(width,

                                                                height,
                                                                96, // These decides the dpi factors 
                                                                96,// The can be changed when we'll have preview options.
                                                                PixelFormats.Pbgra32);
        bitmap.Render(UIElement);

        SaveUsingBitmapTargetRenderer(fileName, bitmap, encoder);
    }


     private static void SaveUsingBitmapTargetRenderer(string fileName, RenderTargetBitmap renderTargetBitmap, BitmapEncoder bitmapEncoder)
    {
        BitmapFrame frame = BitmapFrame.Create(renderTargetBitmap);
        bitmapEncoder.Frames.Add(frame);
        // Save file .
        using (var stream = File.Create(fileName))
        {
            bitmapEncoder.Save(stream);
        }
    }

Call this function as

     SaveUsingEncoder(fileName, frameworkElement, new PngBitmapEncoder());

Hope this will help.

score 0 · Answer 2 · answered Aug 12 '11 at 11:27

0

You could try temporarily taking the control out of its context (might cause problems if bound),transform it to a visivible point or scroll it into view for rendering.

answered Aug 12 '11 at 11:27

H.B.

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what do you mean visible point, I've tried giving it a new size and calling updatelayout() but it reverts to its old size? – Jon Aug 12 '11 at 11:53
A visible point is any point which is guaranteed to be visible, with scrollviewers it's often easier to scroll the viewport rathar than moving the control to the viewport. – H.B. Aug 12 '11 at 12:12

Getting Image from UIElement is cropped to displayed size

2 Answers2