Quick and Easy: Move a Rectangle Using C# In a Windows Store App

My overall blog philosophy is that it’s perfectly fine to blog about old, settled subjects that have been covered to death elsewhere.  I assume this topic is one of those, but I’m blogging it anyway.

I’ve been working on a window store app and I’m at the part where I need to do some animating.  To this end, I’ve been figuring out bits and pieces of windows store app animation which, as it turns out, is quite close to, but not exactly like, XAML based animations in .NET (I’m still coming to grips with the fact that WinRT <> .NET 🙂 ).

This morning I wanted to get a handle on drag and drop operations.  En route to that, I got bogged down moving a rectangle instead :).  Here’s the code that moves a rectangle when the user clicks a button:

   2:              MatrixTransform ct = (MatrixTransform)rectBig.RenderTransform;
   3:              Matrix m = ct.Matrix;
   4:              m.OffsetX += 10;
   5:              m.OffsetY += 10;
   6:              ct.Matrix = m;
   7:              rectBig.RenderTransform = ct;

The trick here is that I can’t directly change OffsetX or OffsetY.  There may be a more clever way of doing this (and if you know and feel like, please post in the comments). 

In order to do this, I need to:

1. Get the MatrixTransform of the rectangle (by casting RenderTransform).

2. Get the Matrix of that guy.

3. Change the Matrix’s offsets.

4. Reassign the Matrix back to the MatrixTransform.

5. Reassign the MatrixTransform back to the Rectangle.

To test it, I put a rectangle and button the screen. When I click the button, the above logic executes and moves the rectangle immediately.

At some point, I’d like to animate this but I have no idea how to get a DoubleAnimation to work on it (Storyboard.SetTargetProperty() is a mystery to me on this for the time being).


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