之后使用该属性的依赖属性？

Question

我正在尝试设置一个名为 Sprite 的对象的依赖属性，一个 sprite 包含 spriteSheet 的字符串，所以我希望能够传递一个 Sprite，然后使用该数据在我的窗口中显示图像控制。

这是我的尝试，因为

    public Sprite Sprite
    {
        get { return (Quiz.Sprite)GetValue(SpriteProperty); }
        set {
            spriteBrush.ImageSource = new BitmapImage(new Uri("/Project;component/" + value.spriteSheet, UriKind.RelativeOrAbsolute));

            spriteTransform.TranslateX = -558;
            spriteTransform.TranslateY = 0;

            SetValue(SpriteProperty, value);
        }
    }

    public static DependencyProperty SpriteProperty = DependencyProperty.Register(
       "Sprite", typeof(Sprite), typeof(spriteView), new PropertyMetadata(new Quiz.Sprite() { spriteSheet = "wp7_buttons.png" }));
}

我如何让 set 方法的该部分运行，正如我在依赖属性文档中读到的那样，SetValue 和 GetValue 在绑定时可能会被直接调用。

Answer 1

没错，您不能使用 SetValue 引入任何逻辑。相反，您应该使用 PropertyValueChanged处理程序。像这样的东西：

public Sprite Sprite
{
    get { return (Quiz.Sprite)GetValue(SpriteProperty); }
    set { SetValue(SpriteProperty, value); }
}

private static void OnSpritPropertyValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) {
    var control = d as YourControl;
    var sprite = e.NewValue as Quiz.Sprite;

    control.spriteBrush.ImageSource = new BitmapImage(new Uri("/Project;component/" + sprite.spriteSheet, UriKind.RelativeOrAbsolute));

    control.spriteTransform.TranslateX = -558;
    control.spriteTransform.TranslateY = 0;
}

public static DependencyProperty SpriteProperty = DependencyProperty.Register(
   "Sprite", typeof(Sprite), typeof(spriteView),
    new PropertyMetadata(new Quiz.Sprite() { spriteSheet = "wp7_buttons.png" }, OnSpritPropertyValueChanged));

Answer 2

添加 DependencyPropertyChangedEventHandler 并将代码从 setter 移至此处：

public Sprite Sprite
{
    get { return (Quiz.Sprite)GetValue(SpriteProperty); }
    set { SetValue(SpriteProperty, value); }
}

public static DependencyProperty SpriteProperty = DependencyProperty.Register(
"Sprite", typeof(Sprite), typeof(SpriteView), new PropertyMetadata(new Quiz.Sprite() { spriteSheet = "wp7_buttons.png" },
SpriteChanged));

private static void SpriteChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    SpriteView view = sender as SpriteView;
    Sprite sprite = e.NewValue as Sprite;
    if (view != null && sprite != null)
    {
        view.spriteBrush.ImageSource = new BitmapImage(new Uri("/Project;component/" + sprite.spriteSheet, UriKind.RelativeOrAbsolute));
        view.spriteTransform.TranslateX = -558;
        view.spriteTransform.TranslateY = 0;
    }
}