InkCanvas Eraser

Question

我有画板作为InkCanvas;我想，所以我已经写了改变橡皮擦尺寸：

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：通过按e

1. 选择橡皮擦，橡皮stylusTip会出现矩形
2. 按下+号来增大尺寸，你不会看到任何改变。为什么？
3. 现在您按i更改编辑模式，将出现墨水提示。
4. 再次按e重新切换到橡皮擦。你会看到橡皮擦的形状已经改变。

为什么不按+符号后？

Answer 1

从help：

“如果你改变了EraserShape，呈现在InkCanvas光标不更新，直到下一个EditingMode变化”

我测试下面的代码，它工作正常：

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; 
}