使用GDI＋对图片进行操作

2013-03-20 22:41 ⁄ 工业·编程 ⁄ 共 2222字 ⁄ 字号小中大 ⁄ 暂无评论

1、图片的显示
// 下面是GDI+要使用的几个头文件
#ifndef ULONG_PTR
#define ULONG_PTR unsigned long*
#endif
#include "Gdiplus.h"
#include <afxole.h>
#include <Atlbase.h>

Gdiplus::GdiplusStartupInput m_gdiplusStartupInput;
ULONG_PTR m_gdiplusToken;
// 初始化GDI+库
void InitGuiPlus()
{
Gdiplus::GdiplusStartup(&m_gdiplusToken, &m_gdiplusStartupInput, NULL);
}

// 关闭GDI+库
void CleanupGuiPlus()
{
Gdiplus::GdiplusShutdown(m_gdiplusToken);
}

Gdiplus::Bitmap * m_pBmp;
// 加载图片
Gdiplus::Bitmap * LoadPic(LPCSTR szPicUrl)
{
Gdiplus::Bitmap * pBmp ＝ NULL;
CFileFind fFind;
if (!fFind.FindFile(szPicUrl))
{
return pBmp;
}
USES_CONVERSION;
// 打开刚才浏览的图片
pBmp = new Gdiplus::Bitmap(A2W(szPicUrl));
return pBmp;
}

// 卸载图片
void UnLoadPic()
{
if (m_pBmp != NULL)
{
delete m_pBmp;
m_pBmp = NULL;
}
}

// 显示图片（在WM_PAINT的响应处理函数对其调用）
void ShowPic(CDC *pDC, Gdiplus::Bitmap *pbmpSrc, int nSrcWidth, int nSrcHeight)
{
ASSERT(pbmpSrc != NULL);
Gdiplus::Graphics graphics(pDC->m_hDC);
graphics.DrawImage(pbmpSrc, 0, 0, nSrcWidth, nSrcHeight);
}

*************************************************************************************************
2、利用GDI+对图片缩放后保存(头文件和初始化代码同1)
// 获取图片的编码信息
BOOL GetImageEncoderCLSID( CLSID& clsid, const wchar_t* format)
{
     UINT num=0, size=0;
     Gdiplus::GetImageEncodersSize(&num, &size);
     Gdiplus::ImageCodecInfo* pImageCodecInfo = (Gdiplus::ImageCodecInfo*)malloc(size);
     if(pImageCodecInfo == NULL)
{
   return FALSE;
}
     Gdiplus::GetImageEncoders(num, size, pImageCodecInfo );
     for( UINT i = 0; i<num; ++i )
     {
         if( wcscmp(pImageCodecInfo[i].MimeType, format) == 0 )
         {
              clsid = pImageCodecInfo[i].Clsid;
              free(pImageCodecInfo);
              return TRUE;
         }
     }
     free(pImageCodecInfo);
pImageCodecInfo = NULL;
     return FALSE;
}

// 按尺寸保存图片
BOOL SavePicture(LPCSTR pszFileUrl, Gdiplus::Image *pSrcBmp, int nSavedWidth, int nSavedHeight)
{
ASSERT(pSrcBmp != NULL);
// 创建预保存的图片
Gdiplus::Bitmap bmpSaved(nSavedWidth, nSavedHeight);
Gdiplus::Graphics * pGraphics = Gdiplus::Graphics::FromImage(&bmpSaved);
// 将pSrcBmp画到pGraphics中
pGraphics->DrawImage(pSrcBmp, 0, 0, nSavedWidth, nSavedHeight);
if (pGraphics == NULL)
{
return FALSE;
}
CLSID clImageClsid;
// 获取图片的编码信息
if (GetImageEncoderCLSID(clImageClsid, L"image/jpeg"))
{
USES_CONVERSION;
// 保存入片
bmpSaved.Save(A2W(pszFileUrl), &clImageClsid, NULL);
delete pGraphics;
pGraphics = NULL;
return TRUE;
}
delete pGraphics;
pGraphics = NULL;
return FALSE;
}