画板系统的设计与实现

1、画板系统的设计与实现本工程以一个比较有趣的例子，来说明如何使用Visual Basic来开发Windows应用程序。本工程将使用VB来开发一个类似“画图”软件的程序，通过此程序，我们可以实现用鼠标画直线、矩形以及不规则线等，可以控制笔线粗细等功能。本系统可以完成以下任务：l 通过自制调色板选取画笔的前景色和背景色。l 用户可以设置控制画笔的粗细，颜色。l 可以画点、线（直线和不规则线）、矩形等。l 指示鼠标坐标，前景背景，按钮工具的信息等。首先，现在窗体上添加各种控件，如图1-1、图1-1画图板的设计窗口控件名称主要控件属性名称属性值功能说明Form1Caption画图板VBBorderSty

2、le3 Fixed DialogStartUpPosition2-屏幕中心Label3名称Label3容纳工具按钮caption工具按钮font宋体，5号，粗体，下划线BorderStyle1-FixedCommand1Style1-Graphical控件数组，为工具按钮ToolTipText分别为：新建、铅笔、画直线、画矩形、画点、橡皮PictureBox名称DrawPic画布，主要的绘画区。BorderStyle1 Fixed SinglePictureBox名称LineCon用来指示绘图的线宽，由其下面的滚动条控制。BackColor &H8000000F&BorderStyle1 Fi

3、xed SingleHScrollBar名称HScroll1控制绘图的线宽。LargeChange1Max20Min1Label名称Info用来显示提示信息等Caption工具指示器BorderStyle1 Fixed Single名称Label4Caption鼠标坐标Line1这是一个线的控件数组，一黑一白，位置相对成立体效果Label2BorderStyle1 Fixed Single存放前景背景颜色Label名称ForeSee存放前景颜色BorderStyle1 Fixed SingleLabel名称BackSee存放背景颜色BorderStyle1 Fixed SingleLabel名

4、称Label1控件数组，用于存放颜料盒，选择不同的背景颜色。BorderStyle1 Fixed SingleBackColor(选择不同的颜色即可)CommandButton名称Command2Caption画板清空名称Command3Caption退出图1-2画图板的运行窗口本系统采用的主要原理：l 系统初始化：完成系统的各项初始化。Dim nToolNum, nMyForeColor, nMyBackColor被访问的工具按钮、前景、背景Dim nStartX, nStartY, nEndX, nEndY As Integer指定开始和结束坐标Dim nLineWidth As Inte

5、ger指定线宽Dim DrawOrNot As Boolean 是否开始画图Private Sub Form_Load()初始化各项参数 nToolNum = 0 nLineWidth = 1 DrawOrNot = False nMyForeColor = RGB(0, 0, 0) nMyBackColor = RGB(255, 255, 255) DrawPic.ForeColor = nMyForeColor DrawPic.BackColor = nMyBackColorEnd Subl 在颜料盒中选定前景和背景：Private Sub Label1_MouseUp(Index As

6、Integer, Button As Integer, Shift As Integer, X As Single, Y As Single) If (Button = 1) Then如果是左键，则进行前景颜色设置 ForeSee.BackColor = Label1(Index).BackColor使用控件数组获取颜色 DemoLine.BorderColor = ForeSee.BackColor显示线的颜色 nMyForeColor = ForeSee.BackColor DrawPic.ForeColor = ForeSee.BackColor End If If (Button =

7、2) Then如果是右键，则进行背景颜色设置 BackSee.BackColor = Label1(Index).BackColor LineCon.BackColor = BackSee.BackColor nMyBackColor = BackSee.BackColor End If nMyForeColor = ForeSee.BackColor nMyBackColor = BackSee.BackColorEnd Subl 用滚动条控制画笔的线宽：Private Sub HScroll1_Change() LineCon.BackColor = BackSee.BackColor D

8、emoLine.BorderWidth = HScroll1.Value DrawPic.DrawWidth = HScroll1.ValueEnd Subl 用鼠标进行画图的过程控制：Private Sub DrawPic_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)依据按下的工具值，来进行坐标和作图方式的选择即DrawMode赋值,分为正常和异或（分别取值13和7）Select Case nToolNum Case 1 DrawPic.CurrentX = X: DrawPic.Curren

9、tY = Y DrawPic.DrawMode = 13 Case 2 nStartX = X: nStartY = Y nEndX = X: nEndY = Y DrawPic.DrawMode = 7 Case 3 nStartX = X: nStartY = Y nEndX = X: nEndY = Y DrawPic.DrawMode = 7 nStartX = X: nStartY = Y Case 4 If Button = 1 Then DrawPic.ForeColor = nMyForeColor Else DrawPic.ForeColor = nMyBackColor E

10、nd If nStartX = X: nStartY = Y DrawPic.DrawMode = 7 DrawPic.PSet (nStartX, nStartY), DrawPic.ForeColor Case 5 DrawPic.CurrentX = X: DrawPic.CurrentY = Y DrawPic.DrawMode = 13 nStartX = X: nStartY = Y End SelectEnd SubPrivate Sub DrawPic_MouseMove(Button As Integer, Shift As Integer, X As Single, Y A

11、s Single) 依据鼠标的移动来进行作图，并根据鼠标的左右键判断用前景还是背景作图 If Button 0 Then If Button = 2 Then DrawPic.ForeColor = nMyBackColor Else DrawPic.ForeColor = nMyForeColor End If Select Case nToolNum Case 1 DrawPic.Line -(X, Y), DrawPic.ForeColor Case 2 DrawPic.Line (nStartX, nStartY)-(nEndX, nEndY), Not (DrawPic.ForeCo

12、lor) DrawPic.Line (nEndX, nEndY)-(X, Y), Not (DrawPic.ForeColor) nStartX = X: nStartY = Y Case 3 DrawPic.Line (nStartX, nStartY)-(nEndX, nEndY), Not (DrawPic.ForeColor), B DrawPic.Line (nEndX, nEndY)-(X, Y), Not (DrawPic.ForeColor), B nStartX = X: nStartY = Y Case 4 DrawPic.PSet (X, Y), nMyForeColor

13、 Case 5 DrawPic.Line -(X, Y), nMyBackColor End Select End If Label4.Caption = X: & X & Y: & Y显示鼠标的坐标位置End SubPrivate Sub Drawpic_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single) 依据按下的工具值，来用正常的绘图方式将画好的图重新绘制一遍，使在鼠标移动过程中的异或方式画的图被覆盖。使之能正常显示。 Select Case nToolNum Case 2 DrawPic.Line

14、 (nEndX, nEndY)-(nStartX, nStartY) DrawPic.DrawMode = 13 DrawPic.Line (nEndX, nEndY)-(nStartX, nStartY), DrawPic.ForeColor Case 3 DrawPic.Line (nStartX, nStartY)-(nEndX, nEndY), Not (DrawPic.ForeColor), B DrawPic.DrawMode = 13 DrawPic.Line (nStartX, nStartY)-(nEndX, nEndY), DrawPic.ForeColor, B End SelectEnd Subl 点击工具按钮现实的提示信息：Private Sub Command1_Click(Index As Integer) Select Case Index Case 0: Info.Caption = 你用的是清除画板 DrawPic.Cls Case 1: nToolNum = 1 Info.Caption = 你用的是铅笔 Case 2: nToolNum = 2 Info.Caption = 你用的是画直线 Case 3: nToolNum