//Gray：黑白
private void GrayButton_Tapped(object sender, TappedRoutedEventArgs e)
{
flyout.Hide();
Layer l = App.Model.Layers[App.Model.Index];
//如果图层不可视或透明
if (l.Visual == false || l.Opacity <= 0)
{
App.Tip(App.resourceLoader.GetString("/Layer/Hided_"));
}
else
{
//Undo：撤销
Undo undo = new Undo();
undo.TargeInstantiation(App.Model.Index, App.Model.CurrentRenderTarget);
App.UndoAdd(undo);
using (CanvasDrawingSession ds = l.CanvasRenderTarget.CreateDrawingSession())
{
if (App.Model.isAnimated == false) //清空：如果无选区
{
ds.Clear(Colors.Transparent);
}
else if (App.Model.isAnimated == true) //选区内清空：如果有选区
{
ds.DrawImage(App.Model.MaskRenderTarget, 0, 0, App.Model.MaskRenderTarget.Bounds, 1, CanvasImageInterpolation.Linear, CanvasComposite.DestinationOut);
}
ds.DrawImage(Adjust.GetGrayscale(App.Model.SecondSourceRenderTarget)); //绘画：特效渲染目标
}
l.SetWriteableBitmap(App.Model.VirtualControl); //刷新缩略图
App.Model.isReRender = true; //重新渲染
App.Model.Refresh++; //画布刷新
}
}