CxImage动态加载图片（判断图片文件类型）

 

 1、打开一张图
可以通过创建一个新的CxImage对象来完成，通过构造函数来打开一张图
CxImage::CxImage(const char * filename, DWORD imagetype)
其中filename是需要打开的文件路径，imagetype是文件类型，支持的类型有：

CXIMAGE_FORMAT_UNKNOWN，CXIMAGE_FORMAT_BMP,CXIMAGE_FORMAT_GIF,CXIMAGE_FORMAT_JPG,CXIMAGE_FORMAT_PNG,CXIMAGE_FORMAT_MNG,CXIMAGE_FORMAT_ICO,CXIMAGE_FORMAT_TIF,CXIMAGE_FORMAT_TGA,CXIMAGE_FORMAT_PCX,CXIMAGE_FORMAT_WBMP,CXIMAGE_FORMAT_WMF,CXIMAGE_FORMAT_J2K,CXIMAGE_FORMAT_JBG,CXIMAGE_FORMAT_JP2,CXIMAGE_FORMAT_JPC,CXIMAGE_FORMAT_PGX,CXIMAGE_FORMAT_PNM,CXIMAGE_FORMAT_RAS,
当然，这么多格式很难记住，我们可以通过如下函数来直接获得文件的格式

 int FindType(const CString& filename)
{
CString ext = filename.Right(filename.GetLength()-filename.ReverseFind('.')-1);
int type = 0;
if (ext == "bmp")     type = CXIMAGE_FORMAT_BMP;
#if CXIMAGE_SUPPORT_JPG
else if (ext=="jpg"||ext=="jpeg") type = CXIMAGE_FORMAT_JPG;
#endif
#if CXIMAGE_SUPPORT_GIF
else if (ext == "gif")    type = CXIMAGE_FORMAT_GIF;
#endif
#if CXIMAGE_SUPPORT_PNG
else if (ext == "png")    type = CXIMAGE_FORMAT_PNG;
#endif
#if CXIMAGE_SUPPORT_MNG
else if (ext=="mng"||ext=="jng") type = CXIMAGE_FORMAT_MNG;
#endif
#if CXIMAGE_SUPPORT_ICO
else if (ext == "ico")    type = CXIMAGE_FORMAT_ICO;
#endif
#if CXIMAGE_SUPPORT_TIF
else if (ext=="tiff"||ext=="tif") type = CXIMAGE_FORMAT_TIF;
#endif
#if CXIMAGE_SUPPORT_TGA
else if (ext=="tga")    type = CXIMAGE_FORMAT_TGA;
#endif
#if CXIMAGE_SUPPORT_PCX
else if (ext=="pcx")    type = CXIMAGE_FORMAT_PCX;
#endif
#if CXIMAGE_SUPPORT_WBMP
else if (ext=="wbmp")    type = CXIMAGE_FORMAT_WBMP;
#endif
#if CXIMAGE_SUPPORT_WMF
else if (ext=="wmf"||ext=="emf") type = CXIMAGE_FORMAT_WMF;
#endif
#if CXIMAGE_SUPPORT_J2K
else if (ext=="j2k"||ext=="jp2") type = CXIMAGE_FORMAT_J2K;
#endif
#if CXIMAGE_SUPPORT_JBG
else if (ext=="jbg")    type = CXIMAGE_FORMAT_JBG;
#endif
#if CXIMAGE_SUPPORT_JP2
else if (ext=="jp2"||ext=="j2k") type = CXIMAGE_FORMAT_JP2;
#endif
#if CXIMAGE_SUPPORT_JPC
else if (ext=="jpc"||ext=="j2c") type = CXIMAGE_FORMAT_JPC;
#endif
#if CXIMAGE_SUPPORT_PGX
else if (ext=="pgx")    type = CXIMAGE_FORMAT_PGX;
#endif
#if CXIMAGE_SUPPORT_RAS
else if (ext=="ras")    type = CXIMAGE_FORMAT_RAS;
#endif
#if CXIMAGE_SUPPORT_PNM
else if (ext=="pnm"||ext=="pgm"||ext=="ppm") type = CXIMAGE_FORMAT_PNM;
#endif
else type = CXIMAGE_FORMAT_UNKNOWN;

return type;
}

具体实例打开一幅图片：

void CProDlg::OnBnClickedButton3()
{
 CString strPicPath;
 CFileDialog dlg(TRUE,NULL,NULL,OFN_HIDEREADONLY|OFN_OVERWRITEPROMPT,_T("图片文件(*.jpg;*.jpeg;*.gif;,*.bmp)|*.jpg;*.jpeg;*.gif;*.bmp|位图文件(*.BMP)|*.BMP||"));
 dlg.m_ofn.lpstrInitialDir=_T(".//");
 if(IDOK==dlg.DoModal())
 {strPicPath.Format(_T("%s"),dlg.GetPathName());}
 CString fileExt;
 int len=strPicPath.GetLength();
 for(int i=len-1;i>=0;i--)
 {if(strPicPath[i]=='.'){fileExt=strPicPath.Mid(i+1);break;}}
 fileExt.MakeLower();
 int type;
 if(fileExt!=_T(""))
 {type=FindType(strPicPath);}
 CxImage image;
 image.Load(strPicPath,type);
 //将整个控件调整为与图像同一尺寸
 GetDlgItem(IDC_PIC1)->SetWindowPos(NULL,0,0,300,300,SWP_NOMOVE);
 CRect zcRect;
 GetDlgItem(IDC_PIC1)->GetClientRect(&zcRect);
 CDC *pDC=GetDlgItem(IDC_PIC1)->GetDC();
 image.Draw(pDC->m_hDC,zcRect.left,zcRect.top,300,300);

}

2、保存一张图
bool CxImage::Save(LPCWSTR filename, DWORD imagetype=0)
参数和上面是一样的。

具体实例;

  void CProDlg::OnBnClickedButton1()
{   float scale=0.5;
 CxImage image,smallImg;
 CString fileName="d://1.jpg";
 CString fileExt;
 int len=fileName.GetLength();
 for(int i=len-1;i>=0;i--)
 {if(fileName[i]=='.'){fileExt=fileName.Mid(i+1);break;}}
 fileExt.MakeLower();
 int type;
 if(fileExt!=_T(""))
 {type=CxImage::GetTypeIdFromName(fileExt);}
 image.Load(fileName);
 image.Resample(image.GetWidth()*scale,image.GetHeight()*scale,1,&smallImg);
 smallImg.Save("d://2.jpg",type);
}

3、得到图形数据，以便在OpenGL中使用材质
BYTE* CxImage::GetBits(DWORD row = 0);
4、得到图形大小
long GetSize();
5、得到图形高度和宽度
DWORD CxImage::GetHeight();
DWORD CxImage::GetWidth();
6、得到文件类型
DWORD CxImage::GetType()  const;
7、得到最后一个错误
char* CxImage::GetLastError();
8、在界面中绘制出来
long CxImage::Draw(HDC hdc, const RECT& rect, RECT* pClipRect=NULL)
HDC 绘图设备，rect 绘图的区域，确定绘图的左上角和右下角坐标。pClipRect，裁剪区域，一般可以和绘图区域一样大小，除非特殊需要。