InkCanvas橡皮

Question

我有InkCanvas的草图；我想改变橡皮擦的大小，所以我写了：

Private Sub Sketchpad_KeyDown(sender As System.Object, e As System.Windows.Input.KeyEventArgs) Handles Sketchpad.KeyDown

If e.Key = Key.OemMinus Then

' Decrease size of Eraser to 5*5 

Sketchpad.EraserShape = New RectangleStylusShape(5, 5)

End If

If e.Key = Key.OemPlus Then

' Increase size of Eraser to 50*50 

Sketchpad.EraserShape = New RectangleStylusShape(50, 50)

End If

If e.Key = Key.I Then
' Change editing mode to Ink
Sketchpad.EditingMode = InkCanvasEditingMode.Ink

End If

If e.Key = Key.E Then
' Change editing mode to Eraser
Sketchpad.EditingMode = InkCanvasEditingMode.EraseByPoint

End If

End Sub

试试这个：

1. 按e键选择橡皮擦，橡皮擦stylusTip将显示为矩形
2. 按+符号以增加大小，您将不会看到任何更改。为什么？
3. 现在按i键改变编辑模式，就会出现墨迹提示。
4. 再次按e键重新切换到橡皮擦。你会看到橡皮擦的形状已经改变了。

为什么不按下+符号呢？

Answer 1

来自帮助

“如果您更改了EraserShape，在InkCanvas上呈现的光标直到下一个EditingMode更改后才会更新。”

我测试了以下代码，它运行得很好：

if (e.Key == Key.OemMinus)
{
    ink.EraserShape = new RectangleStylusShape(5, 5);
    var editMode = ink.EditingMode;
    ink.EditingMode = InkCanvasEditingMode.None;
    ink.EditingMode = editMode;
}
if (e.Key == Key.OemPlus)
{
    ink.EraserShape = new RectangleStylusShape(50, 50);
    var editMode = ink.EditingMode;
    ink.EditingMode = InkCanvasEditingMode.None;
    ink.EditingMode = editMode;
}