使用具有反转Y轴的ScaleTransform进行缩放

Question

我的XAML：

<ScrollViewer Name="MyScrollViewer" CanContentScroll="True">
<Grid Grid.Column="1" Margin="10">
MouseWheel="Grid_OnMouseWheel">
<Grid.RenderTransform>
<ScaleTransform ScaleY="-1" />
</Grid.RenderTransform>
...
</Grid>
</ScrollViewer>

我的代码：

如您所见，我需要左下角的零Y坐标角：

private void Grid_OnMouseWheel(object sender, MouseWheelEventArgs e)
{

UIElement element = (UIElement)sender;
Point position = e.GetPosition(element);

double Width = element.RenderSize.Width;
double Height = element.RenderSize.Height;

Matrix GridMatrix = GUIGrid.LayoutTransform.Value;

if (e.Delta > 0)
{

ScaleFactor += 1;

ScaleTransform Transform = new ScaleTransform(ScaleFactor, ScaleFactor, position.X, position.Y);
Transform.ScaleY = -ScaleFactor;
GUIGrid.RenderTransform = Transform;
}
else
{

ScaleFactor -= 1;

if (ScaleFactor <= 0)
ScaleFactor = 1;

ScaleTransform Transform = new ScaleTransform(ScaleFactor, ScaleFactor, position.X, position.Y);
Transform.ScaleY = -ScaleFactor;
GUIGrid.RenderTransform = Transform;
}
e.Handled = true;
}

我的问题：

我没有得到正确的坐标，我的缩放飞离屏幕。我已经尝试将-Y设置为位置，但这还不够。如果有人可以解释为什么这不符合我的预期呢？

Answer 1

嗯，没有像我希望的那样简单，文档很差！

ScaleTransform Transform = new ScaleTransform();
Transform.Value.ScaleAtPrepend(ScaleFactor, ScaleFactor, Position.X, Position.Y);
Transform.ScaleX = ScaleFactor;
Transform.ScaleY = -ScaleFactor;
GUIGrid.RenderTransform = Transform;

现在按照我的预期工作。