Question

I’m resizing a canvas with touch events as follows:

e.Handled = true;
var transformation = MyCanvas.RenderTransform as MatrixTransform;
var matrix = transformation == null ? Matrix.Identity :transformation.Matrix;

matrix.ScaleAt(e.DeltaManipulation.Scale.X,
               e.DeltaManipulation.Scale.Y,
               e.ManipulationOrigin.X,
               e.ManipulationOrigin.Y);

MyCanvas.RenderTransform = new MatrixTransform(matrix);

The canvas has several child canvasses. I don’t want to resize them and in fact need them to go smaller. So looked at RenderTransform.Inverse but am not having any joy.

Answer 1

You can create a custom canvas by inheriting from Panel with

1. A new dependency property: NonInheritableScale

2. A binding between bind the transform’s scale to the NonInhertiableScale property

3. overrides of the MeasureOverride() and ArrangeOverride() methods,
   so that the take 1.0/NonInhertiableScale.X and 1.0/NonInhertiableScale.Y into account during the layout.

Here is an article on creating custom WPF panels that might help you (a search result, haven’t read it).