用GDI+实现BMP位图转JPG位图(及com对象IPicture转jpg)

 在头文件中先包含GDI+的头和库

 

#ifndef ULONG_PTR
#define ULONG_PTR unsigned long*
#include "GdiPlus.h"
using namespace Gdiplus;
#pragma comment(lib, "gdiplus.lib")
#include <atlconv.h>
#endif

 

在类中定义相关成员变量

 GdiplusStartupInput m_gdiplusStartupInput;
 ULONG_PTR m_gdiplusToken;

 

初始化gdi+

 GdiplusStartup(&m_gdiplusToken, &m_gdiplusStartupInput, NULL);

 

结束时销毁gdi+

 GdiplusShutdown(m_gdiplusToken);

 

转换函数

BOOL CtojpgDlg::MBmpToMImage(CFile& cbfBmp, CFile& cbfImage, CString strType){int iBmpSize = cbfBmp.GetLength();HGLOBAL hMemBmp = GlobalAlloc(GMEM_FIXED, iBmpSize);if (hMemBmp == NULL) return FALSE;IStream* pStmBmp = NULL;CreateStreamOnHGlobal(hMemBmp, FALSE, &pStmBmp);if (pStmBmp == NULL) {GlobalFree(hMemBmp);return FALSE;}BYTE* pbyBmp = (BYTE *)GlobalLock(hMemBmp);cbfBmp.SeekToBegin();cbfBmp.Read(pbyBmp, iBmpSize);Image* imImage = NULL;imImage = Image::FromStream(pStmBmp, FALSE);if (imImage == NULL) {GlobalUnlock(hMemBmp);GlobalFree(hMemBmp);return FALSE;}USES_CONVERSION;CLSID clImageClsid;GetImageCLSID(_T("image/jpeg"), &clImageClsid);HGLOBAL hMemImage = GlobalAlloc(GMEM_MOVEABLE, 0);if (hMemImage == NULL){pStmBmp->Release();GlobalUnlock(hMemBmp);GlobalFree(hMemBmp);if (imImage != NULL) delete imImage;return FALSE;}IStream* pStmImage = NULL;CreateStreamOnHGlobal(hMemImage, TRUE, &pStmImage);if (pStmImage == NULL){pStmBmp->Release();GlobalUnlock(hMemBmp);GlobalFree(hMemBmp);GlobalFree(hMemImage);if (imImage != NULL) delete imImage;return FALSE;}imImage->Save(pStmImage, &clImageClsid);if (pStmImage == NULL) {pStmBmp->Release();pStmImage->Release();GlobalUnlock(hMemBmp);GlobalFree(hMemBmp);GlobalFree(hMemImage);if (imImage != NULL) delete imImage;return FALSE;}LARGE_INTEGER liBegin = {0};pStmImage->Seek(liBegin, STREAM_SEEK_SET, NULL);BYTE* pbyImage = (BYTE *)GlobalLock(hMemImage);cbfImage.SeekToBegin();cbfImage.Write(pbyImage, GlobalSize(hMemImage));if (imImage != NULL) delete imImage;pStmBmp->Release();pStmImage->Release();GlobalUnlock(hMemBmp);GlobalUnlock(hMemImage);GlobalFree(hMemBmp);GlobalFree(hMemImage);return TRUE;}BOOL CtojpgDlg:: GetImageCLSID(const WCHAR* format, CLSID* pCLSID){UINT num = 0;UINT size = 0;ImageCodecInfo* pImageCodecInfo = NULL;GetImageEncodersSize(&num, &size);if(size == 0){return FALSE;}pImageCodecInfo = (ImageCodecInfo *)(malloc(size));if(pImageCodecInfo == NULL)return FALSE;GetImageEncoders(num, size, pImageCodecInfo); // Find for the support of format for image in the windowsfor(UINT i = 0; i < num; ++i){ //MimeType: Depiction for the program image if( wcscmp(pImageCodecInfo[i].MimeType, format) == 0){ *pCLSID = pImageCodecInfo[i].Clsid; free(pImageCodecInfo); return TRUE; } } free(pImageCodecInfo); return FALSE; }

 

上面的方法适用于在知道BMP位图文件时使用,而从IPicture转换到jpg位图就要稍微改下

 

LONG ExportShowPic( LONG nPicIndex, LPCTSTR strSavePath ) //nPicIndex为IPICTURE数组对象索引, { //strSavePath 为jpg图像保存路径 if(m_pIPicture[nPicIndex] == NULL) { return FALSE; } BOOL bResult = FALSE; //int iBmpSize = cbfBmp.GetLength(); HGLOBAL hMemBmp = GlobalAlloc(GMEM_MOVEABLE, 0); if (hMemBmp == NULL) return FALSE; IStream* pStmBmp = NULL; CreateStreamOnHGlobal(hMemBmp, FALSE, &pStmBmp); if (pStmBmp == NULL) { GlobalFree(hMemBmp); return FALSE; } //BYTE* pbyBmp = (BYTE *)GlobalLock(hMemBmp); //cbfBmp.SeekToBegin(); //cbfBmp.Read(pbyBmp, iBmpSize); long OutStream = 0;m_pIPicture[nPicIndex]->SaveAsFile(pStmBmp, TRUE, &OutStream); // Copy Data Stream Image* imImage = NULL; imImage = Image::FromStream(pStmBmp, FALSE); if (imImage == NULL) { GlobalUnlock(hMemBmp); GlobalFree(hMemBmp); return FALSE; } USES_CONVERSION; CLSID clImageClsid; GetImageCLSID(_T("image/jpeg"), &clImageClsid); HGLOBAL hMemImage = GlobalAlloc(GMEM_MOVEABLE, 0); if (hMemImage == NULL) { pStmBmp->Release(); GlobalUnlock(hMemBmp); GlobalFree(hMemBmp); if (imImage != NULL) delete imImage; return FALSE; } IStream* pStmImage = NULL; CreateStreamOnHGlobal(hMemImage, TRUE, &pStmImage); if (pStmImage == NULL) { pStmBmp->Release(); GlobalUnlock(hMemBmp); GlobalFree(hMemBmp); GlobalFree(hMemImage); if (imImage != NULL) delete imImage; return FALSE; } imImage->Save(pStmImage, &clImageClsid); if (pStmImage == NULL) { pStmBmp->Release(); pStmImage->Release(); GlobalUnlock(hMemBmp); GlobalFree(hMemBmp); GlobalFree(hMemImage); if (imImage != NULL) delete imImage; return FALSE; } LARGE_INTEGER liBegin = {0}; pStmImage->Seek(liBegin, STREAM_SEEK_SET, NULL); BYTE* pbyImage = (BYTE *)GlobalLock(hMemImage); //cbfImage.SeekToBegin(); //cbfImage.Write(pbyImage, GlobalSize(hMemImage)); CFile fileJpg; if(fileJpg.Open(strSavePath, CFile::modeCreate | CFile::modeWrite)) { fileJpg.SeekToBegin(); fileJpg.Write(pbyImage, GlobalSize(hMemImage)); } if (imImage != NULL) delete imImage; pStmBmp->Release(); pStmImage->Release(); GlobalUnlock(hMemBmp); GlobalUnlock(hMemImage); GlobalFree(hMemBmp); GlobalFree(hMemImage);bResult = TRUE;return TRUE; }