如何在图像控件上调整图像大小？

Question

I'm trying to resize an image on a UWP Image control (XAML) using

ScaleTransform t = (ScaleTransform)image.RenderTransform;

But am getting an error:

Unable to cast object of type 'Windows.UI.Xaml.Media.MatrixTransform' to type 'Windows.UI.Xaml.Media.ScaleTransform'.

So how do I resize it (not using the Stretch property)?

Answer 1

The existing RenderTransform is of type MatrixTransform which cannot be cast to a ScaleTransform.

You can either replace the existing MatrixTransform with a new ScaleTransform:

image.RenderTransform = new ScaleTransform(2, 2);

or you can update the existing MatrixTransform with the desired scale:

(image.RenderTransform as MatrixTransform).Matrix = new MatrixTransform(2, 0, 0, 2, 0, 0);

Answer 2

Assign a new ScaleTransform to the RenderTransform property once:

image.RenderTransform = new ScaleTransform();

Now you can later safely access it by

var t = (ScaleTransform)image.RenderTransform