[WPF] SizeChanged fires only once

[James Rose]

Hey gang,

I'm learning WPF, or attempting to learn, and I have a user control that I would like to have an image resize when the control resizes. However the SizeChanged event is only firing when I add the control to the window.

The code is simple enough:

        private void Grid_SizeChanged(object sender, SizeChangedEventArgs e)
        {
           MessageBox.Show("Hthis.grdMain.Height.ToString());
        }

What am I doing wrong?

[Eric Veteran]

Are you sure the control is changing sizes? It's working for me in the test I set up in my current project.

You can test it by adding something to force the control to resize by a pixel or two to trigger the event.

Make sure you're not capturing the event at a higher level than the control and "e.Handled = true"-ing it, and don't forget to set the event's Handled property to true if that's all you want to do when it resizes. That will prevent any other routed event handlers from trying to respond to the message. (This trips up MouseUp/Down/Move if you have another control using the PreviewMouse- events without Handling them properly.)

You could also intercept the LayoutUpdated event instead.

[boogerjones]

Like GreyWolf, I bet your grid isn't actually resizing. Put a border on it to make sure. Or show us your XAML.

Also, you may want ActualHeight instead of Height. This is actually more evidence that your grid doesn't have a dynamic layout.

[James Rose]

You both are right, the grid was not resizing, the window was... I feel a bit stupid... but after 18 years with VB, trying out C# and WPF is making me a little foolish. (at least I admit it)

Have a great day.

[Eric Veteran]

Glad it's sorted... WPF does take a bit to get used to.

I've been arguing with routed events all morning trying to implement a gesture system... back/next at the window level, page up/down at container level... :p

[James Rose]

  On 27/07/2011 at 20:14, GreyWolf said:

I've been arguing with routed events all morning trying to implement a gesture system... back/next at the window level, page up/down at container level... :p

Kinect gestures? I am working on that as well, or at least I was until I found a couple of people on the Kinect forums that have a decent process and are working out the details