[00011]-[2015-08-26]-[00]-[Windows 程序设计 ---MFC 截屏--->BMP格式 --->JPG格式]

标签：

HBITMAP CopyScreenToBitmap(LPRECT lpRect)
{
HDC hScrDC, hMemDC; // 屏幕和内存设备描述表
HBITMAP hBitmap, hOldBitmap; // 位图句柄
int nX, nY, nX2, nY2; // 选定区域坐标
int nWidth, nHeight; // 位图宽度和高度
int xScrn, yScrn; // 屏幕分辨率

if (IsRectEmpty(lpRect))
return NULL;

hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL); // 为屏幕创建设备描述表

hMemDC = CreateCompatibleDC(hScrDC); // 为屏幕设备描述表创建兼容的内存设备描述表

nX = lpRect->left;
nY = lpRect->top;
nX2 = lpRect->right;
nY2 = lpRect->bottom;

xScrn = GetDeviceCaps(hScrDC, HORZRES); // 获得屏幕水平分辨率
yScrn = GetDeviceCaps(hScrDC, VERTRES);

if (nX < 0)
nX = 0;
if (nY < 0)
nY = 0;
if (nX2 > xScrn)
nX2 = xScrn;
if (nY2 > yScrn)
nY2 = yScrn;
nWidth = nX2 - nX;
nHeight = nY2 - nY;

hBitmap = CreateCompatibleBitmap(hScrDC, nWidth, nHeight); // 创建一个与屏幕设备描述表兼容的位图
hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap); // 把新位图选到内存设备描述表中
BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, SRCCOPY); // 把屏幕设备描述表拷贝到内存设备描述表中
hBitmap = (HBITMAP)SelectObject(hMemDC, hOldBitmap); // 得到屏幕位图的句柄

DeleteDC(hScrDC);
DeleteDC(hMemDC);

return hBitmap;
}

/*
lpFileName: 位图文件名
*/
BOOL SaveBitmapToFile(HBITMAP hBitmap, LPSTR lpFileName)
{
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, dwBmBitsSize, dwDIBSize, dwWritten; // 调色板大小，位图数据大小，位图文件大小，写入文件字节数
BITMAP Bitmap; //位图属性结构
BITMAPFILEHEADER bmfHdr; // 位图文件头
BITMAPINFOHEADER bi; // 位图信息头
LPBITMAPINFOHEADER lpbi; // 指向位图信息头结构

HANDLE fh, hDib; // 定义文件，分配内存句柄
HPALETTE hPal, hOldPal=NULL; // 调色板句柄

// 计算位图文件每个像素所占字节数
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
wBitCount = 32;
if (wBitCount <= 8)
dwPaletteSize = (1 << wBitCount) * sizeof(RGBQUAD); // 计算调色板大小

// 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;

hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof(BITMAPINFOHEADER)); // 为位图内容分配内存
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi;
// 处理调色板
hPal = (HPALETTE)GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
hDC = GetDC(NULL);
hOldPal = SelectPalette(hDC, 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, (BITMAPINFO*)lpbi, DIB_RGB_COLORS);

if (hOldPal) // 恢复调色板
{
SelectPalette(hDC, 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; // 文件类型: "BM"
dwDIBSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + dwPaletteSize + dwBmBitsSize;
bmfHdr.bfSize = dwDIBSize; // 位图文件大小
bmfHdr.bfReserved1 = 0;
bmfHdr.bfReserved2 = 0;
bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER) + dwPaletteSize;

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

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

return TRUE;
}

// -------------------------------------------------------------------------------------------------------------------------------- //

void CMyDlg::OnButton1()
{
// HBITMAP hBitmap, LPSTR lpFileName
RECT rect = {0, 0, 1900, 1000};
HBITMAP hbmp = CopyScreenToBitmap(&rect);
SaveBitmapToFile(hbmp, "a.bmp");
MessageBox("Save bmp file Successful");
}

int GetEncoderClsid(const WCHAR* format, CLSID* pClsid)
{
UINT num = 0; // number of image encoders
UINT size = 0; // size of the image encoder array in bytes
ImageCodecInfo* pImageCodecInfo = NULL;
GetImageEncodersSize(&num, &size);
if(size == 0)
return -1; // Failure

pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
if(pImageCodecInfo == NULL)
return -1; // Failure

GetImageEncoders(num, size, pImageCodecInfo);
for(UINT j = 0; j < num; ++j)
{
if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
{
*pClsid = pImageCodecInfo[j].Clsid;
free(pImageCodecInfo);
return j; // Success
}
}
free(pImageCodecInfo);
return -1; // Failure
}

void SaveCurScreenJpg(LPCWSTR pszFileName, int xs, int ys, int quality)
{
HWND hwnd = ::GetDesktopWindow();
HDC hdc = GetWindowDC(NULL);
int x = GetDeviceCaps(hdc, HORZRES);
int y = GetDeviceCaps(hdc, VERTRES);
HBITMAP hbmp = ::CreateCompatibleBitmap(hdc, x, y), hold;
HDC hmemdc = ::CreateCompatibleDC(hdc);
hold = (HBITMAP)::SelectObject(hmemdc, hbmp);
BitBlt(hmemdc, 0, 0, x, y, hdc, 0, 0, SRCCOPY);
SelectObject(hmemdc, hold);

Bitmap bit(xs, ys), bit2(hbmp, NULL);
Graphics g(&bit);
g.ScaleTransform((float)xs/x, (float)ys/y);
g.DrawImage(&bit2, 0, 0);

CLSID encoderClsid;
EncoderParameters encoderParameters;

encoderParameters.Count = 1;
encoderParameters.Parameter[0].Guid = EncoderQuality;
encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
encoderParameters.Parameter[0].NumberOfValues = 1;
encoderParameters.Parameter[0].Value = &quality;

GetEncoderClsid(L"image/jpeg", &encoderClsid);
bit.Save(pszFileName, &encoderClsid, &encoderParameters);

::DeleteObject(hbmp);
::DeleteObject(hmemdc);
return;
}

// -------------------------------------------------------------------------------------------------------------------------------- //

// 截屏保存为 jpg 格式需要 GDI+库的支持

void CMyDlg::OnButton2()
{
// TODO: Add your control notification handler code here
SaveCurScreenJpg(L"1.jpg", 1440, 900, 100);
}

[00011]-[2015-08-26]-[00]-[Windows 程序设计 ---MFC 截屏--->BMP格式 --->JPG格式]

标签：

原文地址：http://www.cnblogs.com/Auris/p/4762007.html