asp.net中C实现缩放图片的例子

作者：袖梨 2022-06-25

头文件:

 代码如下 复制代码

#include
#include
#include
#include "gdiplus.h"
#include
using namespace Gdiplus;
#pragma comment(lib, "gdiplus.lib")

CPP:

 代码如下 复制代码
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 www.111com.net
 
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 DrawMainWindow(Image* img,int w,int h)
{
HDC hDC = GetDC(AfxGetMainWnd()->m_hWnd);
if (hDC)
{
Graphics graphics(hDC);
graphics.DrawImage(img,w,h,img->GetWidth(),img->GetHeight());
ReleaseDC(AfxGetMainWnd()->m_hWnd,hDC);
}
 
}
 
void GetThumbnail(LPCSTR srcFile,LPCSTR dstFile,int width,int height,bool constRatio)
{
GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken,&gdiplusStartupInput,NULL);
 
USES_CONVERSION;
Image srcImage(A2W(srcFile));
Image *dstImage;
 
int srcWidth = srcImage.GetWidth();
int srcHeight = srcImage.GetHeight();
 
if( constRatio ){
if ( width / srcWidth < height / srcHeight ) {
height = width * srcHeight / srcWidth;
}
else {
width = height * srcWidth / srcHeight;
}
}
dstImage = srcImage.GetThumbnailImage(width,height);
 
CLSID imgClsid;
GetEncoderClsid(L"image/jpeg",&imgClsid);
dstImage->Save(A2W(dstFile),&imgClsid,NULL);
 
DrawMainWindow(&srcImage,0,0);
DrawMainWindow(dstImage,0,srcImage.GetHeight()+10);
delete dstImage;
dstImage = NULL;
 
//GdiplusShutdown(gdiplusToken);
}

使用方法:
 

 代码如下 复制代码
GetThumbnail("image.jpg","cc.jpg",200,80,TRUE);

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