windows编程之位图的缩放

简介：这里主要介绍的就是讲一个位图在窗体中进行缩放的操作，根据窗体大小的变化，来改变位图的大小；

关键函数：

StretchBlt();具体用法大家可以去msdn上查一下，我就不赘述了。

效果图如下：

代码如下：

代码如下：

#include
#include
#include
#include

HDC hdcmem;//设备内存环境句柄
HBITMAP hbitmap;//位图句柄
BITMAP bitmap;//BITMAP结构

LRESULT CALLBACK WndProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);

int WINAPI WinMain(
  HINSTANCE hInstance,      // handle to current instance
  HINSTANCE hPrevInstance,  // handle to previous instance
  LPSTR lpCmdLine,          // command line
  int nCmdShow              // show state
)
{
	WNDCLASS wndclass;

	wndclass.cbClsExtra = 0;
	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 = "我的窗口";
	wndclass.lpszMenuName = NULL;
	wndclass.style = CS_HREDRAW | CS_VREDRAW;
	RegisterClass(&wndclass); //注册窗口类

	HWND hwnd;
	hwnd = CreateWindow("我的窗口", "窗口", WS_OVERLAPPEDWINDOW, 
		0, 0, 1000, 600, NULL, NULL, hInstance, NULL);

	ShowWindow(hwnd, nCmdShow);
	UpdateWindow(hwnd);

	MSG Msg;	
	while(GetMessage(&Msg, NULL, 0, 0))
	{
		TranslateMessage(&Msg); 
        DispatchMessage(&Msg); 
	}

	return Msg.wParam;
}


LRESULT CALLBACK WndProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
)
{
	HDC hdc;
	PAINTSTRUCT ps;
	HANDLE hb;

	static int  cxClient, cyClient, cxSource, cySource; 
	HDC         hdcClient, hdcWindow ;
	static RECT rect,rect1; 

	switch(uMsg)
	{
	case WM_CREATE:
		hdc = GetDC(hwnd);
		hdcmem = CreateCompatibleDC(hdc);//获取内存设备环境句柄

		GetClientRect(GetDesktopWindow(), &rect);  
		ReleaseDC(hwnd, hdc);

		break;

	case WM_PAINT:
		 
		hdcClient = BeginPaint (hwnd, &ps) ;
        hdcWindow = GetDC(NULL);  
		hb = LoadImage(NULL, "bk.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
		SetStretchBltMode(hdcClient, COLORONCOLOR); 
		
		SelectObject(hdcmem, hb); //将位图选入内存设备	
		GetObject(hb, sizeof(BITMAP), &bitmap); 
		StretchBlt (hdcClient, 0, 0, cxClient, cyClient,  
                      hdcmem, 0, 0, bitmap.bmWidth, bitmap.bmHeight, MERGECOPY);
	
    	
		EndPaint(hwnd, &ps);
	
        ReleaseDC (hwnd, hdcWindow) ;  
 
		DeleteObject(hb);
		break;

	//case WM_QUIT://WM_QUIT 是关闭消息环的

	case WM_CLOSE://WM_CLOSE 是关闭窗口的
		DestroyWindow(hwnd);
		break;

	case WM_DESTROY://WM_DESTROY 是关闭程序的
		DeleteDC(hdcmem); 	
		PostQuitMessage(0);
	    break;

    case WM_SIZE:  
        cxClient = LOWORD (lParam) ;  
        cyClient = HIWORD (lParam) ;  
        break;  

	default:
		return DefWindowProc(hwnd, uMsg, wParam, lParam);
	}

	return 0;
}

资源链接：http://download.csdn.net/detail/u010084308/6705369