VB实现鼠标绘图实例代码

本文所述为VB实现鼠标绘图的实例，该实例实现线条颜色和线宽可自设，当按下鼠标按键时绘图开始并记录最初的起点，如果不是处在绘图状态则退出该过程，如果处在绘图状态则从起点到目前鼠标所在点绘制直线，然后将当前鼠标所在点作为新的起点，当释放鼠标按键时绘图结束。

具体的功能代码如下：

VERSION 5.00
Object = "{F9043C88-F6F2-101A-A3C9-08002B2F49FB}#1.2#0"; "comdlg32.ocx"
Begin VB.Form Form1 
  Caption     =  "鼠标绘图"
  ClientHeight  =  6420
  ClientLeft   =  60
  ClientTop    =  345
  ClientWidth   =  7710
  LinkTopic    =  "Form1"
  ScaleHeight   =  6420
  ScaleWidth   =  7710
  StartUpPosition =  3 '窗口缺省
  Begin VB.CommandButton Command2 
   Caption     =  "清除"
   Height     =  495
   Left      =  5640
   TabIndex    =  7
   Top       =  1440
   Width      =  1335
  End
  Begin VB.Frame Frame1 
   Caption     =  "线宽"
   Height     =  2655
   Left      =  5520
   TabIndex    =  2
   Top       =  2880
   Width      =  1935
   Begin VB.OptionButton Option4 
     Caption     =  "8"
     Height     =  495
     Left      =  240
     TabIndex    =  6
     Top       =  1800
     Width      =  1215
   End
   Begin VB.OptionButton Option3 
     Caption     =  "4"
     Height     =  375
     Left      =  240
     TabIndex    =  5
     Top       =  1320
     Width      =  1335
   End
   Begin VB.OptionButton Option2 
     Caption     =  "2"
     Height     =  375
     Left      =  240
     TabIndex    =  4
     Top       =  840
     Width      =  1095
   End
   Begin VB.OptionButton Option1 
     Caption     =  "1"
     Height     =  255
     Left      =  240
     TabIndex    =  3
     Top       =  480
     Value      =  -1 'True
     Width      =  1335
   End
  End
  Begin VB.CommandButton Command1 
   Caption     =  "设置颜色"
   Height     =  495
   Left      =  5640
   TabIndex    =  1
   Top       =  600
   Width      =  1215
  End
  Begin MSComDlg.CommonDialog CommonDialog1 
   Left      =  4200
   Top       =  3840
   _ExtentX    =  847
   _ExtentY    =  847
   _Version    =  393216
  End
  Begin VB.PictureBox Picture1 
   Height     =  5535
   Left      =  480
   ScaleHeight   =  5475
   ScaleWidth   =  4515
   TabIndex    =  0
   Top       =  480
   Width      =  4575
  End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Dim x1 As Integer  '起点X坐标
Dim y1 As Integer  '起点Y坐标
Dim x2 As Integer  '终点点X坐标
Dim y2 As Integer  '终点Y坐标
Dim flag As Boolean '绘图标志
'设置线的颜色
Private Sub Command1_Click()
  On Error Resume Next
  CommonDialog1.CancelError = True
  CommonDialog1.DialogTitle = "颜色"
  CommonDialog1.ShowColor
  If Err <> 32755 Then
    Picture1.ForeColor = CommonDialog1.Color
  End If
End Sub
'清除Picture1中的图形
Private Sub Command2_Click()
  Picture1.Cls
End Sub
'设置线宽
Private Sub Option1_Click()
  Picture1.DrawWidth = 1
End Sub
Private Sub Option2_Click()
  Picture1.DrawWidth = 2
End Sub
Private Sub Option3_Click()
  Picture1.DrawWidth = 4
End Sub
Private Sub Option4_Click()
  Picture1.DrawWidth = 8
End Sub
Private Sub Form_Load()
  Picture1.Scale (0, 0)-(400, 400)
  flag = False
End Sub
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, _X As Single, Y As Single)
'当按下鼠标按键时绘图开始并记录最初的起点
  flag = True
  x1 = X
  y1 = Y
End Sub
Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, _X As Single, Y As Single)
'如果不是处在绘图状态则退出该过程
'如果处在绘图状态则从起点到目前鼠标所在点绘制直线
'然后将当前鼠标所在点作为新的起点
  If flag = False Then
    Exit Sub
  End If
  If flag = True Then
    x2 = X
    y2 = Y
    Picture1.Line (x1, y1)-(x2, y2)
    x1 = x2
    y1 = y2
  End If
End Sub
Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, _X As Single, Y As Single)
'当释放鼠标按键时绘图结束
  flag = False
End Sub

程序中备有较为详细的注释，相信读者不难理解，读者可以根据自己的喜好对该程序进行修改，使之更加完善！