WPF window 子窗口反馈效果（拉动/渐变)

当子窗口显示后，点击子窗口外部，需要有反馈动画。

实现：

1.事件捕捉

每次点击子窗口外部，即母窗口时，事件捕捉如下

HwndSource hwndSource = PresentationSource.FromVisual(this.Owner) as HwndSource;//窗口过程

hwndSource?.AddHook(WndProc);

也可以调用WindowInteropHelper，获取母窗口句柄。

var hwnd = new WindowInteropHelper(this.Owner).Handle;
if (hwnd != IntPtr.Zero)
{
　　var hwndSource = HwndSource.FromHwnd(hwnd);
　　hwndSource?.AddHook(WndProc);
}

事件中，启动动画

 private static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
         if (msg != 0x20) return IntPtr.Zero;
         if (lParam.ToInt32() == 0x201fffe) _storyboard?.Begin();
         return IntPtr.Zero;
    }

2.动画设置

窗口抖动 动画

            var scaleXDoubleAnimation = new DoubleAnimationUsingKeyFrames();
            var scaleYDoubleAnimation = new DoubleAnimationUsingKeyFrames();

            scaleXDoubleAnimation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0)),Value = 1.0});
            scaleXDoubleAnimation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(100)),Value = 0.9});
            scaleXDoubleAnimation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(200)),Value = 1.0});

            scaleYDoubleAnimation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0)),Value = 1.0});
            scaleYDoubleAnimation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(100)),Value = 0.9});
            scaleYDoubleAnimation.KeyFrames.Add(new EasingDoubleKeyFrame
            {
                KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(200)),
                Value = 1.0
            });

            Storyboard.SetTarget(scaleXDoubleAnimation, window);
            Storyboard.SetTarget(scaleYDoubleAnimation, window);
            Storyboard.SetTargetProperty(scaleXDoubleAnimation, new PropertyPath("(UIElement.RenderTransform).(ScaleTransform.ScaleX)"));
            Storyboard.SetTargetProperty(scaleYDoubleAnimation, new PropertyPath("(UIElement.RenderTransform).(ScaleTransform.ScaleY)"));

            _storyboard = new Storyboard{Children =new TimelineCollection { scaleXDoubleAnimation, scaleYDoubleAnimation }};

窗口阴影 动画

            var animation = new DoubleAnimationUsingKeyFrames();

            animation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0)),Value = 0});
            animation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(200)),Value = 50});
            animation.KeyFrames.Add(new EasingDoubleKeyFrame{KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(400)),Value = 0});

            Storyboard.SetTarget(animation, window);
            Storyboard.SetTargetProperty(animation, new PropertyPath("(FrameworkElement.Effect).(DropShadowEffect.BlurRadius)"));

            _storyboard = new Storyboard
            {
                Children = new TimelineCollection { animation }
            };