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DeleteDC

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說明：
DeleteDC 函式可刪除釋放記憶體中指定的裝置環境

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 DeleteDC Lib "gdi32" Alias "DeleteDC" ( _
    ByVal hdc As Long _
    ) As Long



參數型態及說明：
hdc：Long 要刪除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：
無

VB範例：

檢視原始碼 Visual Basic
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'VB的宣告
Private Declare Function DeleteDC Lib "gdi32" ( _
	ByVal hdc As Long _
	) As Long
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 r1 As Long
 
'移除記憶體中的裝置環境
r1 = DeleteDC(mHdc)
 
Dim r2 As Long
 
'釋放目前執行視窗的裝置環境代碼(Device Context)
r2 = ReleaseDC(Form1.hwnd, hdc)

RB範例：

檢視原始碼 REALBasic
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'RB的宣告
Declare Function DeleteDC Lib "gdi32" ( _
	hdc As Integer _
	) As Boolean
Declare Function CreateCompatibleDC Lib "gdi32" ( _
	hdc As Integer _
	) As Integer
Declare Function ReleaseDC Lib "user32" ( _
	hwnd As Integer, _
	hdc As Integer _
	) As Boolean
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 r1 As Boolean
 
'移除記憶體中的裝置環境
r1 = DeleteDC(mHdc)
 
Dim r2 As Boolean
 
'釋放目前執行視窗的裝置環境代碼(Device Context)
r2 = ReleaseDC(Window1.WinHWND, hdc)

VB.NET範例：

檢視原始碼 VB.NET
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'VB.NET的宣告
<DllImport("gdi32.dll")> _
Shared Function DeleteDC( _
	ByVal hdc As IntPtr _
	) As Boolean
End Function
<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 Boolean
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 r1 As Boolean
 
'移除記憶體中的裝置環境
r1 = DeleteDC(mHdc)
 
Dim r2 As Boolean
 
'釋放目前執行視窗的裝置環境代碼(Device Context)
r2 = ReleaseDC(Me.Handle, hdc)

C#範例：

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//C#的宣告
[DllImport("gdi32")]
public static extern bool DeleteDC(
	IntPtr hdc
	);
[DllImport("gdi32")]
public static extern IntPtr CreateCompatibleDC(
	IntPtr hdc
	);
[DllImport("user32")]
public static extern bool 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);
 
bool r1;
 
//移除記憶體中的裝置環境
r1 = DeleteDC(mHdc);
 
bool r2;
 
//釋放目前執行視窗的裝置環境代碼(Device Context)
r2 = ReleaseDC(this.Handle, hdc);

註釋：
不要用於刪除釋放 GetDC 函式所取得的裝置環境代碼(Device Context)。

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