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Normal Topic Disable Diagram.MouseWheel to cause the view to scroll. (Read 3128 times)
JackPan
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Disable Diagram.MouseWheel to cause the view to scroll.
Apr 9th, 2020 at 4:14pm
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Hi All,

Today I conducted a series of tests on Diagram.

I currently set Diagram.Bounds = "-1000, -1000,2000,2000". ShapeNode.Bounds = "0,0,500,500". I tried to display the ShapeNode as soon as the Diagram was loaded, so I put Diagram. ZoomToRect (ShapeNode.Bounds, true); written in Diagram.Loaded event. Then the scaling value of Diagram is restricted in Diagram.MouseWheel event. I have tried when the zoom value of Diagram reaches the limit value, if continue to zoom, the view will scroll.

I want to prohibit the view from scrolling. The Diagram.MouseWheel event only allows zoom operations on the ShapeNode, and the zoom must be performed at the center of the view.

Any assistance would be appreciated.

Cheers,

Jack
  
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Lyubo
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Re: Disable Diagram.MouseWheel to cause the view to scroll.
Reply #1 - Apr 10th, 2020 at 5:17am
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Hello,

What is the current zoom code that you are using? To make the viewport not shift after zoom, you need to make sure its center point remains the same before and after zooming.

Regards,
Lyubo
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JackPan
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Re: Disable Diagram.MouseWheel to cause the view to scroll.
Reply #2 - Apr 10th, 2020 at 8:07am
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Hello,

The zoom code I currently use is as follows:
private void diagram_MouseWheel (object sender, MouseWheelEventArgs e)
        {
            var imageBounds = imageNode.Bounds;
            var zoomRect = diagram.Viewport;
            var zoomStep = 10;

            if (e.Delta <0)
            {
                zoomRect = new Rect
                (
                    Math.Max ​​(imageBounds.X, zoomRect.X-zoomStep / 2),
                    Math.Max ​​(imageBounds.Y, zoomRect.Y-zoomStep / 2),
                    Math.Min (imageBounds.Width, zoomRect.Width + zoomStep),
                    Math.Min (imageBounds.Height, zoomRect.Height + zoomStep)
                );
            }
            else
            {
                zoomRect = new Rect
                (
                    Math.Min (overlayNode.Bounds.X, zoomRect.X + zoomStep / 2),
                    Math.Min (overlayNode.Bounds.Y, zoomRect.Y + zoomStep / 2),
                    Math.Max ​​(10, zoomRect.Width-zoomStep),
                    Math.Max ​​(10, zoomRect.Height-zoomStep)
                );
            }
  
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Lyubo
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Re: Disable Diagram.MouseWheel to cause the view to scroll.
Reply #3 - Apr 10th, 2020 at 9:00am
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Hello,

Code
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private void diagram_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
	var zoomInMax = overlayNode.Bounds; // The bigger node in your example, replace/inflate if needed by your requirements
	var zoomOutMax = imageNode.Bounds; // The smaller node in your example, replace/inflate if needed by your requirements
	var zoomRect = diagram.Viewport;
	var zoomStep = 10;

	double width, height;
	if (e.Delta < 0)
	{
		width = Math.Min(zoomOutMax.Width, zoomRect.Width + zoomStep);
		height = Math.Min(zoomOutMax.Height, zoomRect.Height + zoomStep);
	}
	else
	{
		width = Math.Max(zoomInMax.Width, zoomRect.Width - zoomStep);
		height = Math.Max(zoomInMax.Height, zoomRect.Height - zoomStep);
	}

	var dw = width - zoomRect.Width;
	var dh = height - zoomRect.Height;
	zoomRect = new Rect(zoomRect.X - dw / 2, zoomRect.Y - dh / 2, width, height);

	diagram.ZoomToRect(zoomRect, true);

	// stop the scrollviewer from scrolling
	e.Handled = true;
}


The above code will carry out a zoom operation with outer limit set to the zoomOutMax variable and inner limit set to the zoomInMax variable. It should remain centered always to the current viewport of the diagram. You can increase/decrease the sizes of the limits as per your requirements.

Regards,
Lyubo
MindFusion
  
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JackPan
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Re: Disable Diagram.MouseWheel to cause the view to scroll.
Reply #4 - Apr 10th, 2020 at 9:50am
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Smiley Smiley Smiley Smiley Smiley
Thank you very much.
  
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