說明:
ReleaseDC 函式可將指定的裝置環境代碼(Device Context)做清除及釋放
引用函式庫:
User32
適用系統:
Windows NT 3.1 或 Windows 95以上
函式原型:
Declare Function ReleaseDC Lib "user32" Alias "ReleaseDC" ( _ ByVal hwnd As Long, _ ByVal hdc As Long _ ) As Long
參數型態及說明:
hwnd:Long 要釋放裝置環境代碼(Device Context)的視窗代碼(Handle)
hdc:Long 要釋放的裝置環境代碼(Device Context)
回傳值:
Long 呼叫成功的話,將會回傳非零的數值;若呼叫失敗的話,則回傳 0
.NET Framework API:
System.Drawing.Graphics.ReleaseHdc
VB範例:
檢視原始碼 Visual Basic
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | 'VB的宣告 Private Declare Function ReleaseDC Lib "user32" ( _ ByVal hwnd As Long, _ ByVal hdc As Long _ ) As Long Private Declare Function GetDC Lib "user32" ( _ ByVal hwnd As Long _ ) As Long Dim hdc As Long '取得目前執行視窗的裝置環境代碼(Device Context) hdc = GetDC(Form1.hwnd) Dim r As Long '釋放目前執行視窗的裝置環境代碼(Device Context) r = ReleaseDC(Form1.hwnd, hdc) |
RB範例:
檢視原始碼 REALBasic
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | 'RB的宣告 Declare Function ReleaseDC Lib "user32" ( _ hwnd As Integer, _ hdc As Integer _ ) As Integer Declare Function GetDC Lib "user32" ( _ hwnd As Integer _ ) As Integer Dim hdc As Integer '取得目前執行視窗的裝置環境代碼(Device Context) hdc = GetDC(Window1.WinHWND) Dim r As Integer '釋放目前執行視窗的裝置環境代碼(Device Context) r = ReleaseDC(Window1.WinHWND, hdc) |
VB.NET範例:
檢視原始碼 VB.NET
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | 'VB.NET的宣告 <DllImport("user32.dll")> _ Shared Function ReleaseDC( _ ByVal hwnd As IntPtr, _ ByVal hdc As IntPtr _ ) As Integer End Function <DllImport("user32.dll")> _ Shared Function GetDC( _ ByVal hwnd As IntPtr _ ) As IntPtr End Function Dim hdc As IntPtr '取得目前執行視窗的裝置環境代碼(Device Context) hdc = GetDC(Me.Handle) Dim r As Integer '釋放目前執行視窗的裝置環境代碼(Device Context) r = ReleaseDC(Me.Handle, hdc) |
C#範例:
檢視原始碼 C#
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | //C#的宣告 [DllImport("user32")] public static extern int ReleaseDC( IntPtr hwnd, IntPtr hdc ); [DllImport("user32")] public static extern IntPtr GetDC( IntPtr hwnd ); IntPtr hdc; //取得目前執行視窗的裝置環境代碼(Device Context) hdc = GetDC(this.Handle); int r; //釋放目前執行視窗的裝置環境代碼(Device Context) r = ReleaseDC(this.Handle, hdc); |
註釋:
若是透過 GetDC 函式來取得的話,不用時要用 ReleaseDC 函式來釋放它;但若是使用 CreateDC 函式所建立的話,則要用 DeleteDC 函式