WPF LayoutChanged不会触发笔刷更改...什么事件发生？

Question

I have an application where I am using WPF to live-render an MVVM-based Control to an external LCD panel. I'm propagating each frame using RenderBitmapTarget in a rendering loop and then handing off the byte buffer. The way I know I need to make a render call as opposed to sitting idle is by setting a flag in the LayoutUpdated handler. This is working amazing except that brush changes (especially in animations) don't trigger LayoutUpdated. In fact, I can't tell what they trigger at all, but finding out would help me avoid busily rendering every single loop pass. Can anyone help me?

Answer 1

I'm not sure if this will help your situation but there is a completed event for animations. Perhaps you could set a flag when animation completes, then check the flag in your render loop.

XAML

<Window.Resources>
    <Storyboard x:Key="Storyboard1">

      <ColorAnimation  Storyboard.TargetProperty="(Shape.Fill).(SolidColorBrush.Color)"
                       Storyboard.TargetName="rectangle"
                       BeginTime='0:0:0'
                       Duration='0:0:3'
                       From='White'
                       To='Blue'
                       Completed='ColorAnimation_Completed'>

      </ColorAnimation>
    </Storyboard>
  </Window.Resources>
  <Window.Triggers>
    <EventTrigger RoutedEvent="FrameworkElement.Loaded">
      <BeginStoryboard Storyboard="{StaticResource Storyboard1}" />
    </EventTrigger>

  </Window.Triggers>
  <Grid>
    <Rectangle x:Name="rectangle"
               Fill="#FFF4F4F5"
               HorizontalAlignment="Left"
               Height="93"
               Margin="57,64,0,0"
               Stroke="Black"
               VerticalAlignment="Top"
               Width="130" />

  </Grid>

Code

    private bool _colorChanged = false;
    private void ColorAnimation_Completed(object sender, EventArgs e) {
      _colorChanged = true;

      // restart animation here if necessary
    }