Win32GDI 学习

在Win32下面获取屏幕的高度和宽度：

int x=GetSystemMetrics(SM_CXSCREEN);//屏幕的宽度

int y=GetSystemMetrics(SM_CYSCREEN);//屏幕的高度

在Win32下绘制位图:

HBITMAP hbm=LoadBitmap(hInstance,MAKEINTRESOURCE(iResource)); //iResource为资源ID,hInstance可为NULL

BITMAP bm;

GetObject(hBm,sizeof(BITMAP),&bm);//获取位图信息

SelectObject(hdcsrc,hbm);

BitBlt(hdcdest,xpos,ypos,width,height,hdcsrc,0,0,SRCCOPY);

将CBitmap 保存为bmp文件

bool SaveBitmapToFile(CBitmap* bitmap, LPSTR lpFileName)
{
HBITMAP hBitmap;    // 为刚才的屏幕位图句柄
HDC hDC; //设备描述表
int iBits; //当前显示分辨率下每个像素所占字节数
WORD wBitCount; //位图中每个像素所占字节数
DWORD dwPaletteSize = 0, //定义调色板大小
dwBmBitsSize,  //位图中像素字节大小
dwDIBSize,   //位图文件大小
dwWritten;  //写入文件字节数
BITMAP Bitmap; //位图属性结构
BITMAPFILEHEADER bmfHdr; //位图文件头结构
BITMAPINFOHEADER bi; //位图信息头结构
LPBITMAPINFOHEADER lpbi; //指向位图信息头结构
HANDLE fh,   //定义文件
hDib,    //分配内存句柄
hPal,   //调色板句柄
hOldPal = NULL;

//计算位图文件每个像素所占字节数
hBitmap = (HBITMAP)*bitmap;
hDC = CreateDC("DISPLAY",NULL,NULL,NULL);
iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);
DeleteDC(hDC);

if (iBits <= 1)
wBitCount = 1;
else if (iBits <= 4)
wBitCount = 4;
else if (iBits <= 8)
wBitCount = 8;
else if (iBits <= 24)
wBitCount = 24;
else if (iBits <= 32)
wBitCount = 32;

//计算调色板大小
if (wBitCount <= 8)
dwPaletteSize = (1 << wBitCount) * sizeof (RGBQUAD);

//设置位图信息头结构
GetObject(hBitmap, sizeof (BITMAP), (LPSTR)&Bitmap);
bi.biSize = sizeof (BITMAPINFOHEADER);
bi.biWidth = Bitmap.bmWidth;
bi.biHeight = Bitmap.bmHeight;
bi.biPlanes = 1;
bi.biBitCount = wBitCount;
bi.biCompression = BI_RGB;
bi.biSizeImage = 0;
bi.biXPelsPerMeter = 0;
bi.biYPelsPerMeter = 0;
bi.biClrUsed = 0;
bi.biClrImportant = 0;

dwBmBitsSize = ((Bitmap.bmWidth * wBitCount+31) / 32) * 4 * Bitmap.bmHeight;

//为位图内容分配内存
hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof (BITMAPINFOHEADER));
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi;

// 处理调色板
hPal = GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
hDC = ::GetDC(NULL);
hOldPal = ::SelectPalette(hDC, (HPALETTE)hPal, FALSE);
RealizePalette(hDC);
}

//   获取该调色板下新的像素值
GetDIBits(hDC, hBitmap, 0, (UINT) Bitmap.bmHeight,
(LPSTR)lpbi + sizeof (BITMAPINFOHEADER) + dwPaletteSize,
(LPBITMAPINFO)lpbi, DIB_RGB_COLORS);

//恢复调色板
if (hOldPal)
{
SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);
RealizePalette(hDC);
::ReleaseDC(NULL, hDC);
}

//创建位图文件
fh = CreateFile(lpFileName, GENERIC_WRITE,
0, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);

if (fh == INVALID_HANDLE_VALUE)
return FALSE;

//   设置位图文件头
bmfHdr.bfType = 0x4D42;     //   "BM"
dwDIBSize = sizeof (BITMAPFILEHEADER)
+ sizeof (BITMAPINFOHEADER)
+ dwPaletteSize + dwBmBitsSize;
bmfHdr.bfSize = dwDIBSize;
bmfHdr.bfReserved1 = 0;
bmfHdr.bfReserved2 = 0;
bmfHdr.bfOffBits = (DWORD)sizeof (BITMAPFILEHEADER)
+ (DWORD)sizeof (BITMAPINFOHEADER)
+ dwPaletteSize;

//   写入位图文件头
WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);

//   写入位图文件其余内容
WriteFile(fh, (LPSTR)lpbi, dwDIBSize,
&dwWritten, NULL);

//清除
GlobalUnlock(hDib);
GlobalFree(hDib);
CloseHandle(fh);

return TRUE;
}