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Ive been agonizing over it for a while now. What I have is a window with a scrollviewer that contains a canvas. Im trying to zoom in on whatever is in the center of the window, not necessarily the center of the canvas. So if they zoom in and scroll up/down/left/right, it will give the effect of zooming in on whatever new is in the center of the window. Im trying to do this by using a scale transform in the canvas' layouttransform property. The code I have works great when I load the canvas and its in portrait view, however, many times the canvas will need to be rotated 90, 180, 270 degrees and this is where I run into the problem. I apply a rotatetransform of 90 degrees to the layout transform and when I try to zoom in, the scroll bars jump around up and down, left and right instead of staying constant. Here is my code: public void performTransforms(double scale, double rotation) { TransformGroup tmpLayoutTrans = new TransformGroup(); TransformGroup tmpRenderTrans = new TransformGroup(); //adjust the currentRotation if it goes past 360 or -360 if (currentRotation + rotation != 360 && currentRotation + rotation != -360) { currentRotation += rotation; } else { currentRotation = 0; //take it back to 0 } // If not rotated set width=x, height=y. If its been rotated, we need to flip // the two sides if (currentRotation == 0 || currentRotation == 180) { this.Width = maxX; this.Height = maxY; } else { this.Width = maxY; this.Height = maxX; } tmpLayoutTrans.Children.Add(new RotateTransform(currentRotation)); tmpLayoutTrans.Children.Add(new ScaleTransform(scale, scale)); //add the transformations to this canvas this.LayoutTransform = tmpLayoutTrans; this.RenderTransform = tmpRenderTrans; // Get the center point of the window, scrollviewer and canvas Window1 window = ((Window1)ParentHost); ScrollViewer sv = window.svContent; Point svCenter = new Point(sv.ActualWidth / 2, sv.ActualHeight / 2); Point windowCenter = sv.PointToScreen(svCenter); Point zoomPt = new Point(); // Move the scroll bars so the center of the window always stays in the center when zooming if (this.Parent != null) { zoomPt = this.PointFromScreen(windowCenter); sv.ScrollToHorizontalOffset((zoomPt.X * scale) - (sv.ActualWidth / 2)); sv.ScrollToVerticalOffset((zoomPt.Y * scale) - (sv.ActualHeight / 2)); } }Again this works if the rotation is zero, but if its anything else it does not.
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