制作半透明窗體

領測軟件測試網 函數SetLayeredWindowAttributes
　　使用這個函數，可以輕松的實現半透明窗體。按照微軟的要求，透明窗體窗體在創建時應使用WS_EX_LAYERED參數（用CreateWindowEx），或者在創建后設置該參數（用SetWindowLong），我選用后者。全部函數、常量聲明如下：
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function SetLayeredWindowAttributes Lib "user32" (ByVal hwnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long
　 　其中hwnd是透明窗體的句柄，crKey為顏色值，bAlpha是透明度，取值范圍是[0,255]，dwFlags是透明方式，可以取兩個值：當取值為LWA_ALPHA時，crKey參數無效，bAlpha參數有效；當取值為LWA_COLORKEY時，bAlpha參數有效而窗體中的所有顏色為crKey的地方將變為透明－－這個功能很有用：我們不必再為建立不規則形狀的窗體而調用一大堆區域分析、創建、合并函數了，只需指定透明處的顏色值即可，哈哈哈哈！請看具體代碼。
Private Const WS_EX_LAYERED = &H80000
Private Const GWL_EXSTYLE = (-20)
Private Const LWA_ALPHA = &H2
Private Const LWA_COLORKEY = &H1
代碼一：一個半透明窗體
Private Sub Form_Load()
　　Dim rtn As Long
　　rtn = GetWindowLong(hwnd, GWL_EXSTYLE)
　　rtn = rtn Or WS_EX_LAYERED
　　SetWindowLong hwnd, GWL_EXSTYLE, rtn
　　SetLayeredWindowAttributes hwnd, 0, 200, LWA_ALPHA
End Sub

代碼二：形狀不規則的窗體
Private Sub Form_Load()
　　Dim rtn As Long
　　BorderStyler=0
　　rtn = GetWindowLong(hwnd, GWL_EXSTYLE)
　　rtn = rtn Or WS_EX_LAYERED
　　SetWindowLong hwnd, GWL_EXSTYLE, rtn
　　SetLayeredWindowAttributes hwnd, &HFF0000, 0, LWA_COLORKEY '將扣去窗口中的藍色
End Sub

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