[转]GDI+ 总结一： 保存图像文件

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

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

 

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

 

幸好，有 GetImageDecoders函数作为参照

#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;
    */
}