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How do I call DrawElement on RowUIElement?
posted

Here's what I'm trying to do in general.

I want to, upon dragging a row, capture that row as an image and drag that instead of the built-in windows icons.  I've got this working nicely using BitBlt at the moment - to a Bitmap from the current screen and onto a Form.

The only problem is there are cases where my grid is partially hidden inside a splitter panel.  So a part of the row may be hidden at the bottom for example.  So when I start to drag and capture the image at the moment, what happens is it only captures the visible part of the row.  The hidden part becomes blank.

So I thought I'd use RowUIElement.Draw - didn't work so well.  I didn't get anything drawn.

Then I tried DrawElement but that didn't work either.  And I don't know if it's because I didn't fill out UIElementDrawParams struct or what.

What I might try next is use DrawToBitmap on control but that seems like inefficient.

Here's the relevant part:

            RowUIElement rowUi = row.GetUIElement() as RowUIElement;
            System.Diagnostics.Debug.Assert(rowUi != null, "row.GetUIElement() must not be null.");
            RowCellAreaUIElement cellsUi = rowUi.ChildElements[2] as RowCellAreaUIElement;
            // index 0 contains the expand/collapse indicator, 1 contains the row selector
            using (Graphics g = Control.CreateGraphics())
            {
                Bitmap bm = new Bitmap(cellsUi.Rect.Width, cellsUi.Rect.Height, g);
                using (Graphics gbm = Graphics.FromImage(bm))
                {
                    Rectangle r = new Rectangle(Point.Empty, cellsUi.Rect.Size);
                    //cellsUi.Draw(gbm, r, false, AlphaBlendMode.Disabled);
                    UIElementDrawParams drawParams = new UIElementDrawParams();
                    cellsUi.DrawElement(ref drawParams);
                    bm.Save(@"c:\temp\test.bmp", System.Drawing.Imaging.ImageFormat.Bmp);
                    return CreateWindow(gbm, cellsUi.Rect, _selected.Count > 1);
                }
            }

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  • 469350
    Suggested Answer
    Offline posted

    Hi,

    I'm not exactly sure why this isn't drawing anything for you. But I can tell you that using DrawElement is not going to help you much. The grid is optimized so that it doesn't both creating UIElement for anything outside the clip rect. So any cells that are not visible on the screen won't get displayed, anyway - essentially leaving you with the same problem you have with BitBlt.

     

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