(壹) 創建壹個支持GridLength類型的動畫類
新建壹個繼承AnimationTimeLine的類GridLengthAnimation, 簡單實現2個依賴屬性"From", "To".代碼如下:
internal class GridLengthAnimation : AnimationTimeline
{
static GridLengthAnimation()
{
FromProperty = DependencyProperty.Register("From", typeof(GridLength),
typeof(GridLengthAnimation));
ToProperty = DependencyProperty.Register("To", typeof(GridLength),
typeof(GridLengthAnimation));
}
public static readonly DependencyProperty FromProperty;
public GridLength From
{
get
{
return (GridLength)GetValue(GridLengthAnimation.FromProperty);
}
set
{
SetValue(GridLengthAnimation.FromProperty, value);
}
}
public static readonly DependencyProperty ToProperty;
public GridLength To
{
get
{
return (GridLength)GetValue(GridLengthAnimation.ToProperty);
}
set
{
SetValue(GridLengthAnimation.ToProperty, value);
}
}
接下來就來依次重載或者實現AnimationTimeLine類的成員,
1. 重載CreateInstanceCore, 代碼如下:
protected override System.Windows.Freezable CreateInstanceCore()
{
return new GridLengthAnimation();
}
2. 重載GetCurrentValue以返回動畫的當前值, 代碼如下:
public override object GetCurrentValue(object defaultOriginValue,
object defaultDestinationValue, AnimationClock animationClock)
{
double fromVal = ((GridLength)GetValue(GridLengthAnimation.FromProperty)).Value;
double toVal = ((GridLength)GetValue(GridLengthAnimation.ToProperty)).Value;
if (fromVal > toVal)
{
return new GridLength((1 - animationClock.CurrentProgress.Value) * (fromVal - toVal) + toVal,
((GridLength)GetValue(GridLengthAnimation.FromProperty)).GridUnitType);
}
else
return new GridLength(animationClock.CurrentProgress.Value * (toVal - fromVal) + fromVal,
((GridLength)GetValue(GridLengthAnimation.ToProperty)).GridUnitType);
}
3. 重寫TargetPropertyType 屬性以指示相應的動畫所生成輸出的Type, 代碼如下:
public override Type TargetPropertyType
{
get
{
return typeof(GridLength);
}
}
ok, 通過上面的步驟我們已經寫好了GridLengthAnimation類, 接下來就是如何使用此類.
(二)xaml使用此類, 代碼如下:
<Window.Resources>
<Storyboard x:Key="sbDock">
<common:GridLengthAnimation BeginTime="00:00:00" Storyboard.TargetName="_cellLeft" Storyboard.TargetProperty="Width">
</common:GridLengthAnimation>
</Storyboard>
</Window.Resources>
<Grid x:Name="LayoutRoot" Background="White">
<Grid.RowDefinitions>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition x:Name="_cellLeft" Width="300"/>
<ColumnDefinition x:Name="_cellRight" Width="*"/>
</Grid.ColumnDefinitions>
</Grid>
(三)c#使用此類, 代碼如下:
Storyboard sbDock = this.FindResource("sbDock") as Storyboard;
if (sbDock != null)
{
SplineDoubleKeyFrame sdKeyFrame1 = new SplineDoubleKeyFrame(TransformRadius,
KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1)));
(sbDock.Children[0] as DoubleAnimationUsingKeyFrames).KeyFrames.Clear();
(sbDock.Children[0] as DoubleAnimationUsingKeyFrames).KeyFrames.Add(sdKeyFrame1);
(sbDock.Children[1] as GridLengthAnimation).From = new GridLength(300, GridUnitType.Pixel);
(sbDock.Children[1] as GridLengthAnimation).To = new GridLength(0, GridUnitType.Pixel);
sbDock.Begin();
}