Graphics不能正常构造的奇怪问题

[aimeast]

下面的代码GetLastError都是返回0，
到了pGraphics=new Graphics(hWnd)这里，pGraphics就变成了NULL。
我用的是vs2008，非托管程序。

	DWORD e=GetLastError();
	HWND hWnd=GetDesktopWindow();e=GetLastError();
	hDesktop=GetDC(hWnd);e=GetLastError();
	//hDesktop=GetDC(0);
	pGraphics=new Graphics(hWnd);e=GetLastError();
	Status s=pGraphics->GetLastStatus();
	Color c(200,200,200);
	Pen p(c);
	pGraphics->DrawRectangle(&p,10,10,100,100);
	pGraphics->ReleaseHDC(hDesktop);
	delete pGraphics;
	ReleaseDC(NULL,hDesktop);

[greatws]

如果参数是HWND要2个参数吧？1个参数是HDC
Graphics(HWND hwnd,BOOL icm);

[aimeast]

[Quote=引用 1 楼 greatws 的回复:]
如果参数是HWND要2个参数吧？1个参数是HDC
Graphics(HWND hwnd,BOOL icm);

[/Quote]
忘了说了，用pGraphics=new Graphics(hDesktop);也不行

[TianChong]

1.楼主初始化了没有啊?
CWinApp::InitInstance方法之前，初始化GDI+库，添加两条语句：
GdiplusStartupInput m_gdiplusStartupInput;
GdiplusStartup(&m_pGdiToken,&m_gdiplusStartupInput,NULL);
// 或者在构造函数中添加。

2.使用以下方法而非NEW方法看看?
Graphics graphics( pDC->m_hDC ); //或你的hDesktop 又或直接使用窗口句柄作为参数也是可行的,
如:Graphics graphics(hWnd);

[cnzdgs]

    DWORD e=GetLastError();
    //HWND hWnd=GetDesktopWindow();e=GetLastError();
    //hDesktop=GetDC(hWnd);e=GetLastError();
    hDesktop=GetDC(0);
    pGraphics=new Graphics(hWnd);e=GetLastError();
    Status s=pGraphics->GetLastStatus();
    Color c(200,200,200);
    Pen p(c);
    pGraphics->DrawRectangle(&p,10,10,100,100);
    pGraphics->ReleaseHDC(hDesktop);
    delete pGraphics;
    ReleaseDC(NULL,hDesktop);

另外初始化时要执行GdiplusStartup。

[biweilun]

GdiplusStartup,LZ没有初始化吧

[光宇广贞]

Graphics::Graphics(Image*) Creates a Graphics object that is associated with an Image object.
Graphics::Graphics(HDC) Creates a Graphics object that is associated with a specified device context.
Graphics::Graphics(HDC,HANDLE) Creates a Graphics object that is associated with a specified device context and a specified device.
Graphics::Graphics(HWND,BOOL) Creates a Graphics object that is associated with a specified window.

此四种重载。你挑一个吧……不存在的重载法你调用的话会出问题的。比如你现在所做的那样……

[wencan2010]

我也遇到这种情况
求解