所謂圖形熱點(diǎn)就是指定圖形或圖像上的某部分區(qū)域,當(dāng)鼠標(biāo)在這部分區(qū)域上單擊或雙擊時(shí),就像命令按鈕一樣會(huì)引發(fā)相應(yīng)事件。筆者在VB 5中用Windows提供的三個(gè)API函數(shù)輕松實(shí)現(xiàn)了任何形狀的圖形熱點(diǎn),在此具體介紹這一技術(shù)的實(shí)現(xiàn)步驟。 首先在VB5中新建一"標(biāo)準(zhǔn)EXE工程",設(shè)置窗體Form1的ScaleMode屬性為3。在窗體代碼的聲明部分定義如下三個(gè)API函數(shù): Private Type POINTAPI x As Long y As Long End Type Private Declare Function CreatePolygonRgn Lib "gdi32" (lpPoint As POINTAPI, ByVal nCount As Long, ByVal nPolyFillMode As Long) As Long Private Declare Function DeleteObject Lib "gdi32"(ByVal hObject As Long) As Long Private Declare Function PtInRegion Lib "gdi32" (ByVal hRgn As Long,ByVal x As Long, ByVal y As Long) As Long 函數(shù)說(shuō)明:CreatePolygonRgn( )函數(shù)是用來(lái)創(chuàng)建一個(gè)圖形熱點(diǎn)對(duì)象,lpPoint參數(shù)為形成圖形熱點(diǎn)區(qū)的第一個(gè)邊界點(diǎn)坐標(biāo),nCount參數(shù)指出了邊界點(diǎn)的個(gè)數(shù)(如nCount<3時(shí),將無(wú)法形成一個(gè)封閉區(qū)域),nPolyFillMode參數(shù)指定填充模式,該函數(shù)返回圖形熱點(diǎn)對(duì)象(Long型);DeleteObject( )函數(shù)用來(lái)刪除一個(gè)由hObject參數(shù)指定的對(duì)象;PtInRegion( )函數(shù)用來(lái)判斷某坐標(biāo)(由參數(shù)x、y指出)是否在hRgn圖形熱 點(diǎn)對(duì)象指出的熱點(diǎn)區(qū)內(nèi),若是返回1,否則返回0。 其次在申明部分再添入下列自定義變量: Const MAXCOUNT = 30 '熱點(diǎn)區(qū)邊界點(diǎn)的最多個(gè)數(shù) Dim RgnPt(MAXCOUNT) As POINTAPI '熱點(diǎn)數(shù)組 Dim RgnObject, RgnCount, flag As Long 然后在Form1窗體的上方創(chuàng)建一個(gè)PictureBox控件,設(shè)置名稱為P1 ,ScaleMode屬性為3,Picture屬性指定一幅BMP圖像。在P1的MouseMove事件和MouseDown事件中添入下列代碼: Private Sub P1_MouseDown(button As Integer, shift As Integer, x As Single, y As Single) If button = 1 Then '必須按下鼠標(biāo)左鍵才有效 RgnPt(RgnCount).x = x RgnPt(RgnCount).y = y RgnCount = RgnCount + 1 End If End Sub Private Sub P1_MouseMove(button As Integer, shift As Integer, x As Single, y As Single) If PtInRegion(RgnObject, x, y) = 1 Then Label1.ForeColor = QBColor(12) Label1.Caption = " 進(jìn)入圖形熱點(diǎn)區(qū)!鼠標(biāo)形狀變?yōu)樯陈睿?quot; P1.MousePointer = 11 '設(shè)置鼠標(biāo)形狀為沙漏狀 ElseIf flag = 1 Then Label1.ForeColor = 0 Label1.Caption = " 沒(méi)有進(jìn)入圖形熱點(diǎn)區(qū)!" P1.MousePointer = 0 End If End Sub 接著在P1的下方并排創(chuàng)建兩個(gè)CommandButton控件,Caption屬性分別設(shè)為"創(chuàng)建熱點(diǎn)"和"使用熱點(diǎn)", 名稱分別設(shè)為CrtRgn(對(duì)應(yīng)"創(chuàng)建熱點(diǎn)")和DspRgn。在這兩個(gè)命令按鈕的下方創(chuàng)建一個(gè)Label控件作為操作 提示區(qū),取默認(rèn)名Label1,Caption屬性設(shè)為空,BackColor設(shè)為白色, BorderStyle屬性設(shè)為1,字體為黑體加粗小四號(hào)。雙擊CrtRgn和DspRgn,在它們的Click事件中分別添入以下代碼: Private Sub CrtRgn_Click() Dim tmp As Long RgnCount = 0 tmp = DeleteObject(RgnObject) Label1.Caption = " 在圖像上單擊鼠標(biāo)左鍵來(lái)創(chuàng)建圖形熱點(diǎn)的范圍!"+ _ "至少應(yīng)在不同位置單擊三次以上,否則形不成封閉區(qū)域!" flag = 0 End Sub Private Sub DspRgn_Click() RgnObject = CreatePolygonRgn(RgnPt(0), RgnCount, 1) flag = 1 End Sub 最后在窗體代碼的任意位置添入Form_Load()事件: Private Sub Form_Load() ScaleMode = 3 P1.ScaleMode = 3 End Sub 按F5運(yùn)行后,首先單擊"創(chuàng)建熱點(diǎn)"按鈕,在圖像區(qū)域內(nèi)的不同位置 單擊鼠標(biāo)左鍵,最好單擊三次以上,否則形不成熱點(diǎn)區(qū)。然后單擊"使用熱點(diǎn)"按鈕,在圖像框內(nèi)移動(dòng)鼠標(biāo),你會(huì)發(fā)現(xiàn)當(dāng)鼠標(biāo)進(jìn)入熱點(diǎn)區(qū)后, 形狀變?yōu)樯陈睢1疚闹械某绦騼H為演示程序,在實(shí)際應(yīng)用中,可以事先創(chuàng)建好熱點(diǎn)區(qū)數(shù)組,然后在熱點(diǎn)區(qū)的MouseDown( )事件中添入相應(yīng)的代碼,即可使用圖形熱點(diǎn)代替命令按鈕。 本程序在VB5/Win 95、Win 98下通過(guò)。
|
溫馨提示:喜歡本站的話,請(qǐng)收藏一下本站!