1、畫(huà)板系統(tǒng)的設(shè)計(jì)與實(shí)現(xiàn)本工程以一個(gè)比較有趣的例子，來(lái)說(shuō)明如何使用Visual Basic來(lái)開(kāi)發(fā)Windows應(yīng)用程序。本工程將使用VB來(lái)開(kāi)發(fā)一個(gè)類似“畫(huà)圖”軟件的程序，通過(guò)此程序，我們可以實(shí)現(xiàn)用鼠標(biāo)畫(huà)直線、矩形以及不規(guī)則線等，可以控制筆線粗細(xì)等功能。本系統(tǒng)可以完成以下任務(wù)：l 通過(guò)自制調(diào)色板選取畫(huà)筆的前景色和背景色。l 用戶可以設(shè)置控制畫(huà)筆的粗細(xì)，顏色。l 可以畫(huà)點(diǎn)、線（直線和不規(guī)則線）、矩形等。l 指示鼠標(biāo)坐標(biāo)，前景背景，按鈕工具的信息等。首先，現(xiàn)在窗體上添加各種控件，如圖1-1、圖1-1畫(huà)圖板的設(shè)計(jì)窗口控件名稱主要控件屬性名稱屬性值功能說(shuō)明Form1Caption畫(huà)圖板VBBorderSty

2、le3 Fixed DialogStartUpPosition2-屏幕中心Label3名稱Label3容納工具按鈕caption工具按鈕font宋體，5號(hào)，粗體，下劃線BorderStyle1-FixedCommand1Style1-Graphical控件數(shù)組，為工具按鈕ToolTipText分別為：新建、鉛筆、畫(huà)直線、畫(huà)矩形、畫(huà)點(diǎn)、橡皮PictureBox名稱DrawPic畫(huà)布，主要的繪畫(huà)區(qū)。BorderStyle1 Fixed SinglePictureBox名稱LineCon用來(lái)指示繪圖的線寬，由其下面的滾動(dòng)條控制。BackColor &H8000000F&BorderStyle1 Fi

3、xed SingleHScrollBar名稱HScroll1控制繪圖的線寬。LargeChange1Max20Min1Label名稱Info用來(lái)顯示提示信息等Caption工具指示器BorderStyle1 Fixed Single名稱Label4Caption鼠標(biāo)坐標(biāo)Line1這是一個(gè)線的控件數(shù)組，一黑一白，位置相對(duì)成立體效果Label2BorderStyle1 Fixed Single存放前景背景顏色Label名稱ForeSee存放前景顏色BorderStyle1 Fixed SingleLabel名稱BackSee存放背景顏色BorderStyle1 Fixed SingleLabel名

4、稱Label1控件數(shù)組，用于存放顏料盒，選擇不同的背景顏色。BorderStyle1 Fixed SingleBackColor(選擇不同的顏色即可)CommandButton名稱Command2Caption畫(huà)板清空名稱Command3Caption退出圖1-2畫(huà)圖板的運(yùn)行窗口本系統(tǒng)采用的主要原理：l 系統(tǒng)初始化：完成系統(tǒng)的各項(xiàng)初始化。Dim nToolNum, nMyForeColor, nMyBackColor被訪問(wèn)的工具按鈕、前景、背景Dim nStartX, nStartY, nEndX, nEndY As Integer指定開(kāi)始和結(jié)束坐標(biāo)Dim nLineWidth As Inte

5、ger指定線寬Dim DrawOrNot As Boolean 是否開(kāi)始畫(huà)圖Private Sub Form_Load()初始化各項(xiàng)參數(shù) nToolNum = 0 nLineWidth = 1 DrawOrNot = False nMyForeColor = RGB(0, 0, 0) nMyBackColor = RGB(255, 255, 255) DrawPic.ForeColor = nMyForeColor DrawPic.BackColor = nMyBackColorEnd Subl 在顏料盒中選定前景和背景：Private Sub Label1_MouseUp(Index As

6、Integer, Button As Integer, Shift As Integer, X As Single, Y As Single) If (Button = 1) Then如果是左鍵，則進(jìn)行前景顏色設(shè)置 ForeSee.BackColor = Label1(Index).BackColor使用控件數(shù)組獲取顏色 DemoLine.BorderColor = ForeSee.BackColor顯示線的顏色 nMyForeColor = ForeSee.BackColor DrawPic.ForeColor = ForeSee.BackColor End If If (Button =

7、2) Then如果是右鍵，則進(jìn)行背景顏色設(shè)置 BackSee.BackColor = Label1(Index).BackColor LineCon.BackColor = BackSee.BackColor nMyBackColor = BackSee.BackColor End If nMyForeColor = ForeSee.BackColor nMyBackColor = BackSee.BackColorEnd Subl 用滾動(dòng)條控制畫(huà)筆的線寬：Private Sub HScroll1_Change() LineCon.BackColor = BackSee.BackColor D

8、emoLine.BorderWidth = HScroll1.Value DrawPic.DrawWidth = HScroll1.ValueEnd Subl 用鼠標(biāo)進(jìn)行畫(huà)圖的過(guò)程控制：Private Sub DrawPic_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)依據(jù)按下的工具值，來(lái)進(jìn)行坐標(biāo)和作圖方式的選擇即DrawMode賦值,分為正常和異或（分別取值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) 依據(jù)鼠標(biāo)的移動(dòng)來(lái)進(jìn)行作圖，并根據(jù)鼠標(biāo)的左右鍵判斷用前景還是背景作圖 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顯示鼠標(biāo)的坐標(biāo)位置End SubPrivate Sub Drawpic_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single) 依據(jù)按下的工具值，來(lái)用正常的繪圖方式將畫(huà)好的圖重新繪制一遍，使在鼠標(biāo)移動(dòng)過(guò)程中的異或方式畫(huà)的圖被覆蓋。使之能正常顯示。 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 點(diǎn)擊工具按鈕現(xiàn)實(shí)的提示信息：Private Sub Command1_Click(Index As Integer) Select Case Index Case 0: Info.Caption = 你用的是清除畫(huà)板 DrawPic.Cls Case 1: nToolNum = 1 Info.Caption = 你用的是鉛筆 Case 2: nToolNum = 2 Info.Caption = 你用的是畫(huà)直線 Case 3: nToolNum