Question

我想在矩形上使用pointanimation。我在WPF工作。如果我创建故事板并且只写DoubleAnimation工作。如果我添加PointAnimation系统崩溃并写信给我。

在类型＆＃39; example.MainWindow＆＃39;上调用构造函数。匹配指定的绑定约束会引发异常。＆＃39;

如果没有触发器可以使用这个选项吗？为什么这不起作用？

<Window.Resources>
  <Storyboard x:Key="move">
    <DoubleAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="Width" To="100" Duration="0:0:2"></DoubleAnimation>
    <PointAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="Center" To="100,100" Duration="0:0:2"></PointAnimation>
  </Storyboard>    
</Window.Resources>

Answer 1

故事板的问题是没有{point}类型的Center属性可以设置动画。

背后的实际错误

The invocation of the constructor on type 'example.MainWindow' that matches the specified binding constraints threw an exception.'

是

Cannot resolve all property references in the property path 'Center'. Verify that applicable objects support the properties.

下面的

是使用Canvas.Left和Canvas.Top来实现类似行为的示例

    <Storyboard x:Key="move">
        <DoubleAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="Width" To="100" Duration="0:0:2"></DoubleAnimation>
        <DoubleAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="(Canvas.Left)" To="100" Duration="0:0:2"></DoubleAnimation>
        <DoubleAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="(Canvas.Top)" To="100" Duration="0:0:2"></DoubleAnimation>
    </Storyboard>

使用PointAnimation示例设置位置

定义一个具有附加属性的类来保存值

class RectangleHelper : DependencyObject
{
    public static Point GetLocation(DependencyObject obj)
    {
        return (Point)obj.GetValue(LocationProperty);
    }

    public static void SetLocation(DependencyObject obj, Point value)
    {
        obj.SetValue(LocationProperty, value);
    }

    // Using a DependencyProperty as the backing store for Location.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty LocationProperty =
        DependencyProperty.RegisterAttached("Location", typeof(Point), typeof(RectangleHelper), new PropertyMetadata(new Point(), OnLocationChanged));


    private static void OnLocationChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        Point newValue = (Point)e.NewValue;

        d.SetValue(Canvas.LeftProperty, newValue.X);
        d.SetValue(Canvas.TopProperty, newValue.Y);
    }
}

在上面的代码中我在属性更改处理程序中操作矩形上的Canvas.Left和Canvas.Top

然后xaml as

<Storyboard x:Key="move">
    <DoubleAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="Width" From="1" To="100" Duration="0:0:2"></DoubleAnimation>
    <PointAnimation Storyboard.TargetName="rec" Storyboard.TargetProperty="(l:RectangleHelper.Location)" To="100,100" Duration="0:0:2"></PointAnimation>
</Storyboard>

我为“位置”做了示例，您也可以通过一些计算来实现中心。

PointAnimation没有使用触发器

1 个答案: