GDI+ 摘要： 保存图像文件

要保存图像文件，必须先获得图像的编码格式信息。可是GDI+没有直接提供这个函数：GetEncoderClsid(const WCHAR* format, CLSID* pClsid)

 

因此须要我们自己写一个 GetEncoderClsid 取得图像编码格式的函数

 

幸好，有 GetImageDecoders函数作为參照

 #include <windows.h>
 #include <gdiplus.h>
 #include <stdio.h>
 using namespace Gdiplus;

 INT main()
 {
    // Initialize GDI+.
    GdiplusStartupInput gdiplusStartupInput;
    ULONG_PTR           gdiplusToken;
    GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

    UINT  num;        // number of image decoders
    UINT  size;       // size, in bytes, of the image decoder array

    ImageCodecInfo* pImageCodecInfo;

    // How many decoders are there?
    // How big (in bytes) is the array of all ImageCodecInfo objects?
    GetImageDecodersSize(&num, &size);

    // Create a buffer large enough to hold the array of ImageCodecInfo
    // objects that will be returned by GetImageDecoders.
    pImageCodecInfo = (ImageCodecInfo*)(malloc(size));

    // GetImageDecoders creates an array of ImageCodecInfo objects
    // and copies that array into a previously allocated buffer.
    // The third argument, imageCodecInfos, is a pointer to that buffer.
    GetImageDecoders(num, size, pImageCodecInfo);

    // Display the graphics file format (MimeType)
    // for each ImageCodecInfo object.
    for(UINT j = 0; j < num; ++j)
    {
       wprintf(L"%s\n", pImageCodecInfo[j].MimeType);
    }

    free(pImageCodecInfo);
    GdiplusShutdown(gdiplusToken);
    return 0;
 }

The preceding code produces the following output:

 

image/bmp
image/jpeg
image/gif
image/x-emf
image/x-wmf
image/tiff
image/png
image/x-icon

 

仿照上例 ，我们编写自己的。获得编码格式的函数GetEncoderClsid()

 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
 }

 

保存图像文件：

 

Example_1:

 VOID Example_SaveFile(HDC hdc)
 {
    Graphics graphics(hdc);

    // Create an Image object based on a PNG file.
    Image  image(L"Mosaic.png");

    // Draw the image.
    graphics.DrawImage(&image, 10, 10);

    // Construct a Graphics object based on the image.
    Graphics imageGraphics(&image);

    // Alter the image.
    SolidBrush brush(Color(255, 0, 0, 255));
    imageGraphics.FillEllipse(&brush, 20, 30, 80, 50);

    // Draw the altered image.
    graphics.DrawImage(&image, 200, 10);

    // Save the altered image.
    CLSID pngClsid;
    GetEncoderClsid(L"image/png", &pngClsid);
    image.Save(L"Mosaic2.png", &pngClsid, NULL);
 }

 

Example_2:

 void CMyView::SavePic(HBITMAP hBitmap, CString szPicFilePath)
 {
     if(!hBitmap) return;

     if(PathFileExists(szPicFilePath))
         CFile::Remove(szPicFilePath);

     BITMAP bm;
     GetObject(hBitmap,sizeof(BITMAP),&bm);
     WORD BitsPerPixel=bm.bmBitsPixel;

     using namespace Gdiplus;
     Bitmap* bitmap=Bitmap::FromHBITMAP(hBitmap,NULL);
     EncoderParameters encoderParameters;
     ULONG compression;
     CLSID clsid;

     if(BitsPerPixel==1)
     {
         compression=EncoderValueCompressionCCITT4;
     }
     else
     {
         compression=EncoderValueCompressionLZW;
     }
     GetEncoderClsid(L"image/tiff", &clsid);

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

     bitmap->Save(szPicFilePath,&clsid,&encoderParameters);
     delete bitmap;
     /*
     compression=100;
     GetEncoderClsid(L"image/jpeg", &clsid);

     encoderParameters.Count = 1;
     encoderParameters.Parameter[0].Guid = EncoderQuality;
     encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
     encoderParameters.Parameter[0].NumberOfValues = 1;
     encoderParameters.Parameter[0].Value =&compression;
     */
 }

 转会：http://blog.csdn.net/shuilan0066/article/details/7084742