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CreateCompatibleDC

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說明：
CreateCompatibleDC 函式在記憶體中建立指定的裝置環境代碼(Device Context)一樣的裝置環境

引用函式庫：
GDI32

適用系統：
Windows NT 3.1 或 Windows 95以上

函式原型：

Declare Function CreateCompatibleDC Lib "gdi32" Alias "CreateCompatibleDC" ( _
    ByVal hdc As Long _
    ) As Long



參數型態及說明：
hdc：Long 要在記憶體中建立的裝置環境代碼(Device Context)

回傳值：
Long 呼叫成功的話，將會回傳建立後的裝置環境代碼(Device Context)；若呼叫失敗的話，則回傳 NULL

.NET Framework API：
System.Drawing.Graphics.FromHdc

VB範例：

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'VB的宣告
Private Declare Function CreateCompatibleDC Lib "gdi32" ( _
	ByVal hdc As Long _
	) As Long
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 mHdc As Long
 
'在記憶體中建立一個指定裝置環境
mHdc = CreateCompatibleDC(hdc)
 
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：

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'RB的宣告
Declare Function CreateCompatibleDC Lib "gdi32" ( _
	hdc As Integer _
	) As Integer
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 mHdc As Integer
 
'在記憶體中建立一個指定裝置環境
mHdc = CreateCompatibleDC(hdc)
 
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：

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'VB.NET的宣告
<DllImport("gdi32.dll")> _
Shared Function CreateCompatibleDC( _
	ByVal hdc As IntPtr _
	) As IntPtr
End Function
<DllImport("user32.dll")> _
Shared Function ReleaseDC( _
	ByVal hwnd As IntPtr, _
	ByVal hdc As IntPtr _
	) As UInteger
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 mHdc As IntPtr
 
'在記憶體中建立一個指定裝置環境
mHdc = CreateCompatibleDC(hdc)
 
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：

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//C#的宣告
[DllImport("gdi32")]
public static extern IntPtr CreateCompatibleDC(
	IntPtr hdc
	);
[DllImport("user32")]
public static extern uint 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);
 
IntPtr mHdc;
 
//在記憶體中建立一個指定裝置環境
mHdc = CreateCompatibleDC(hdc);
 
uint 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 hdc 參數是 NULL 的話，則會建立目前應用程式畫面的裝置環境。不用時要用 DeleteDC 函式來釋放它

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