Hi,

It might be possible to do that using ZoomToRect. Zoom to a RectangleF centered around the mouse position, so that it is larger than the current visible area if you wish to zoom out, or smaller than it if you wish to zoom in.

You can get the document coordinates of the visible area and the mouse like this:

RectangleF visible = fc.ClientToDoc(fc.ClientRectangle);
PointF mousePos = fc.ClientToDoc(fc.ScreenToClient(MousePosition));

Then create a new RectangleF from [mousePos - visible.size / 2] to [mousePos + visible.size / 2], call its Inflate() method with a positive value to zoom out or a negative one to zoom in, and finally call the flowchart's ZoomToRect() method.

I hope that helps,
Stoyan

Sorry, I meant PointToClient.

Stoyan

The RectangleF constructor takes (x,y,width,height) arguments. Try that with visible.Size.Width and visible.Size.Height as values for the last two parameters.

Stoyan

Excellent support. It works fine. Thank you.

regards

Steffen

Hi,

Try this if you need the diagram point at current mouse position to remain at the same position after zoom:

private void OnMouseWheel(object sender, MouseEventArgs e)
{
	PointF docPointAtMousePos = diagramView.ClientToDoc(e.Location);

	int factorToIncrese = e.Delta * SystemInformation.MouseWheelScrollLines / 120;
	diagramView.ZoomFactor += factorToIncrese;

	PointF newPointAtMousePos = diagramView.ClientToDoc(e.Location);
	diagramView.ScrollX -= newPointAtMousePos.X - docPointAtMousePos.X;
	diagramView.ScrollY -= newPointAtMousePos.Y - docPointAtMousePos.Y;
} 

I hope that helps,
Stoyan