图片显示问题

xiayuxuan91 2012-10-28 02:02:18

图片显示一次，最小化后窗口还原就空白了。

#include"Beauty.h"

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow)

{

	WNDCLASS wndclass; MSG msg;

	HWND hwnd;

	int Screen_Height,Screen_Width;//记录屏幕尺寸



	wndclass.cbClsExtra=wndclass.cbWndExtra=0;

	wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);

	wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);

	wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);

	wndclass.hInstance=hInstance;

	wndclass.lpfnWndProc=WndProc;

	wndclass.lpszClassName=L"美化窗口类";

	wndclass.lpszMenuName=0;

	wndclass.style=CS_HREDRAW |CS_VREDRAW;



	if(!RegisterClass(&wndclass))

	{

		MessageBox(NULL,L"Error with Registing window class !",L"Information",MB_OK);

		return -1;

	}

	Screen_Height=GetSystemMetrics(SM_CYSCREEN);

	Screen_Width=GetSystemMetrics(SM_CXSCREEN);

	Screen_Width=Screen_Width/2-300;

	Screen_Height=Screen_Height/2-205;

	hwnd=CreateWindow(L"美化窗口类",L"惜雨出品", WS_VISIBLE|WS_MINIMIZEBOX|WS_CLIPSIBLINGS\

		|WS_CAPTION|WS_SYSMENU,Screen_Width,Screen_Height,600,410,NULL,NULL,hInstance,NULL);

	ShowWindow(hwnd,SW_NORMAL);

	UpdateWindow(hwnd);

	while(GetMessage(&msg,NULL,NULL,NULL))

	{

		TranslateMessage(&msg);

		DispatchMessage(&msg);

	}

	return msg.wParam;

}



LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)

{

	HINSTANCE hInstance;//实例句柄

	static HBITMAP hbitmap;

	static int BMP_Height,BMP_Width;//位图宽度和高度



	BITMAP bitmap;

	HANDLE handle;

	HDC hdc,hdcmem;//创建兼容设备句柄

	int error;

	PAINTSTRUCT ps;



	switch(message)

	{

	case WM_CREATE:

		hInstance=((LPCREATESTRUCT)lParam)->hInstance;

		hbitmap=LoadBitmap(hInstance,MAKEINTRESOURCE(IDB_BITMAP1));

		error=GetLastError();

		GetObject(hbitmap,sizeof(BITMAP),&bitmap);

		BMP_Width=bitmap.bmWidth;

		BMP_Height=bitmap.bmHeight;

		return 0;



	case WM_PAINT:

		hdc=BeginPaint(hwnd,&ps);

		//EndPaint(hwnd,&ps);

		//DeleteDC(hdc);

		//return 0;



	//case WM_ERASEBKGND:

	//	hdc=GetDC(hwnd);

		hdcmem=CreateCompatibleDC(hdc);

		handle=SelectObject(hdcmem,hbitmap);

		BitBlt(hdc,0,0,BMP_Width,BMP_Height,hdcmem,0,0,SRCCOPY);

		SelectObject(hdc,handle);

		DeleteDC(hdc);

		EndPaint(hwnd,&ps);

		return 1;



	case WM_CLOSE:

		DestroyWindow(hwnd);

		PostQuitMessage(0);

		return 0;

	}

	return DefWindowProc(hwnd,message,wParam,lParam);

	

}

不应该是这样的啊！！！
元芳，你怎么看？另附上效果对比：

最小化还原后：

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qwhw0827 2012-10-28

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不错的作品，可惜还不会编写。羡慕

xiayuxuan91 2012-10-28

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Kao了，每次都是靠自己。都没人帮忙。奉上答案~~hdcmem=CreateCompatibleDC(hdc);对应的没有DeleteDC(hdcmem);
Debug两次发现第二次调用handle=SelectObject(hdcmem,hbitmap);时候，handle的值为0.而GetLastError返回没有任何错误。果断发现~~应该如此，但不明白为什么。求解答

xiayuxuan91 2012-10-28