VC实现：bmp转jpg、jpg转bmp、截屏保存jpg

1.下载(GDI+ for VC6.0 SDK)GDIPlus文件将其中的Includes和Lib中的文件拷到vc目录下的Includes和Lib文件夹中. 下载地址：http://www.codeguru.com/code/legacy/gdi/GDIPlus.zip(引用他人的) 2.在你将要使用GDI+的工程中，完成初始化工作： 在StdAfx.h中加入 #define ULONG_PTR unsigned long #include <Gdiplus.h> using namespace Gdiplus; 3.在C×App头文件中加入 ULONG_PTR m_gdiplusToken; 4.在 BOOL C×App::InitInstance() 中添加 GdiplusStartupInput m_gdiplusStartupInput; GdiplusStartup(&m_gdiplusToken, &m_gdiplusStartupInput, NULL); 5.在int CXApp::ExitInstance()加入(这个方法需要自己加入 在ClassWizard 中，注意在ClassName中选择CXApp,Messages列表框中选择ExitInstance) Gdiplus::GdiplusShutdown(m_gdiplusToken); 6.在Project->stting->Link->Object/libary中加入gdiplus.lib 此时GDI+设置成功。

需要GDI+,如果没有请看：vc6.0 下设置GDI+

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
}

/****************BMP转JPG*********用法示例**************************

Bitmap newbitmap(L"d://d.bmp");//加载BMP
const unsigned short *pFileName=L"d://new.jpg";//保存路径
SaveFile(&newbitmap,pFileName );

************************************************************/

void SaveFile(Bitmap* pImage, const wchar_t* pFileName)//
{
EncoderParameters encoderParameters;
CLSID jpgClsid;
GetEncoderClsid(L"image/jpeg", &jpgClsid);
encoderParameters.Count = 1;
encoderParameters.Parameter[0].Guid = EncoderQuality;
encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
encoderParameters.Parameter[0].NumberOfValues = 1;

// Save the image as a JPEG with quality level 100.
ULONG quality;
quality = 100;
encoderParameters.Parameter[0].Value = &quality;
Status status = pImage->Save(pFileName, &jpgClsid, &encoderParameters);
if (status != Ok)
{
wprintf(L"%d Attempt to save %s failed./n", status, pFileName);
}
}

// 将当前屏幕保存成为jpg图片
// 参数 xs = 图象x岽笮? ys = 图象y轴大小, quality = jpeg图象质量
void SaveCurScreenJpg(LPCWSTR pszFileName, int xs, int ys, int quality)
{
HWND hwnd = ::GetDesktopWindow();
HDC hdc = GetWindowDC(NULL);
int x = GetDeviceCaps(hdc, HORZRES);
int y = GetDeviceCaps(hdc, VERTRES);
HBITMAP hbmp = ::CreateCompatibleBitmap(hdc, x, y), hold;
HDC hmemdc = ::CreateCompatibleDC(hdc);
hold = (HBITMAP)::SelectObject(hmemdc, hbmp);
BitBlt(hmemdc, 0, 0, x, y, hdc, 0, 0, SRCCOPY);
SelectObject(hmemdc, hold);

Bitmap bit(xs, ys), bit2(hbmp, NULL);
Graphics g(&bit);
g.ScaleTransform((float)xs/x, (float)ys/y);
g.DrawImage(&bit2, 0, 0);

CLSID encoderClsid;
EncoderParameters encoderParameters;

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

GetEncoderClsid(L"image/jpeg", &encoderClsid);
bit.Save(pszFileName, &encoderClsid, &encoderParameters);

::DeleteObject(hbmp);
::DeleteObject(hmemdc);
return;
}

HBITMAP ReturnHBITMAP(CString FileName)//FileName可能是bmp、dib、png、gif、jpeg/jpg、tiff、emf等文件的文件名
{
Bitmap tempBmp(FileName.AllocSysString()) ;
Color backColor;
HBITMAP HBitmap;
tempBmp.GetHBITMAP(backColor,&HBitmap);
return HBitmap;

}