实现鼠标手写板(.Net)

本文是一个实现手写板的简单小示例，当鼠标按下时开始写字，鼠标松开时停止写字。

原理非常简单，当触发MouseDown事件时记录起始坐标startPoint，随着鼠标的移动触发MouseMove事件，记录当前坐标currentPoint，并以startPoint和currentPoint两点画直线，刷新startPoint的坐标。

实现代码如下：

Public Class Form1
Private graphics As Graphics
Private startPoint As Point
Private currentPoint As Point
Private flagDraw As Boolean

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
graphics = Me.CreateGraphics
End Sub

Private Sub Form1_MouseDown(sender As Object, e As MouseEventArgs) Handles Me.MouseDown
startPoint = e.Location
flagDraw = True
End Sub

Private Sub Form1_MouseMove(sender As Object, e As MouseEventArgs) Handles Me.MouseMove
If flagDraw Then
currentPoint = e.Location
graphics.DrawLine(New Pen(Brushes.Black), startPoint, currentPoint)
startPoint = currentPoint
End If
End Sub

Private Sub Form1_MouseUp(sender As Object, e As MouseEventArgs) Handles Me.MouseUp
flagDraw = False
End Sub

End Class