c++ 抓取桌面屏幕並轉爲jpg圖片

抓取屏幕代碼

char* getScreen(unsigned long &jpg_size){	
	HWND DeskWnd=::GetDesktopWindow();//獲取桌面窗口句柄
	 RECT DeskRC;
	::GetClientRect(DeskWnd,&DeskRC);//獲取窗口大小
	HDC DeskDC=GetDC(DeskWnd);//獲取窗口DC
	HBITMAP DeskBmp=::CreateCompatibleBitmap(DeskDC,DeskRC.right,DeskRC.bottom);//兼容位圖
	HDC memDC=::CreateCompatibleDC(DeskDC);//兼容DC
	SelectObject(memDC,DeskBmp);//把兼容位圖選入兼容DC中
	BitBlt(memDC,0,0,DeskRC.right,DeskRC.bottom,DeskDC,0,0,SRCCOPY);
	BITMAP bmInfo;
	DWORD bmDataSize;
	char *bmData;//位圖數據
	GetObject(DeskBmp,sizeof(BITMAP),&bmInfo);//根據位圖句柄，獲取位圖信息
	bmDataSize=bmInfo.bmWidthBytes*bmInfo.bmHeight;//計算位圖數據大小
	bmData=new char[bmDataSize];//分配數據
	BITMAPFILEHEADER bfh;//位圖文件頭
	bfh.bfType=0x4d42;
	bfh.bfSize=bmDataSize+54;
	bfh.bfReserved1=0;
	bfh.bfReserved2=0;
	bfh.bfOffBits=54;
	BITMAPINFOHEADER bih;//位圖信息頭
	bih.biSize=40;
	bih.biWidth=bmInfo.bmWidth;
	bih.biHeight=bmInfo.bmHeight;
	bih.biPlanes=1;
	bih.biBitCount=24;
	bih.biCompression=BI_RGB;
	bih.biSizeImage=bmDataSize;
	bih.biXPelsPerMeter=0;
	bih.biYPelsPerMeter=0;
	bih.biClrUsed=0;
	bih.biClrImportant=0;
	::GetDIBits(DeskDC,DeskBmp,0,bmInfo.bmHeight,bmData,(BITMAPINFO *)&bih,DIB_RGB_COLORS);//獲取位圖數據部分
	ReleaseDC(DeskWnd,DeskDC);
	DeleteDC(memDC);
	DeleteObject(DeskBmp);
    int sumSize = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+bmDataSize;
    char * stream = new char[sumSize];
	memcpy(stream,&bfh,sizeof(BITMAPFILEHEADER));
	memcpy(stream+sizeof(BITMAPFILEHEADER),&bih,sizeof(BITMAPINFOHEADER));
	memcpy(stream+sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER),bmData,bmDataSize);
	delete bmData;
	bmData=NULL;
	/*HANDLE hFile=CreateFile(_T("d:\\Screen.bmp"),GENERIC_WRITE,0,NULL,CREATE_ALWAYS,
	FILE_ATTRIBUTE_NORMAL,0);//創建文件
	DWORD dwSize;
	WriteFile(hFile,(void *)stream,sumSize,&dwSize,0);//寫入位圖文件頭
	::CloseHandle(hFile);//關閉文件句柄*/;
	char*p1=rgb_to_jpeg(reinterpret_cast<unsigned char*>(stream),jpg_size,bih.biWidth,bih.biHeight);
	delete stream;
	stream=NULL;
	return p1;
 
}

對應編譯好的jpeg.lib庫文件下載地址

轉爲jpg圖片代碼

char * rgb_to_jpeg(unsigned char *rgb,unsigned long &jpg_size,int biWidth,int bmHeight)
{   
    struct jpeg_compress_struct jcs;
    struct jpeg_error_mgr jem;
    JSAMPROW row_pointer[1];
    int row_stride=0;
 
    unsigned char *jpg_buf=NULL;
 
    jcs.err = jpeg_std_error(&jem);
    jpeg_create_compress(&jcs);
 
    //printf("jpeg_mem_dest\n");
    jpeg_mem_dest(&jcs,&jpg_buf,&jpg_size);
           
    jcs.image_width =biWidth;  
    jcs.image_height =bmHeight;
 
    jcs.input_components = 3;//1;  
    jcs.in_color_space = JCS_RGB;//JCS_GRAYSCALE;  
 
    jpeg_set_defaults(&jcs);  
    jpeg_set_quality(&jcs,30,TRUE);
       
    jpeg_start_compress(&jcs, TRUE);
    row_stride =jcs.image_width * 3;
       
    while(jcs.next_scanline < jcs.image_height){//對每一行進行壓縮  
        row_pointer[0] = &rgb[(jcs.image_height-jcs.next_scanline-1) * row_stride];
        (void)jpeg_write_scanlines(&jcs,row_pointer, 1);
    }   
    jpeg_finish_compress(&jcs);
    jpeg_destroy_compress(&jcs);
	/*printf("jpg_size = %lu\n",jpg_size);
	FILE *p;
	p= fopen("d:\\04.jpg","wb");
	if(p==NULL)
    printf("error in fopen\n");
	fwrite(jpg_buf,1,jpg_size,p);
	fclose(p);*/
    return reinterpret_cast<char*>(jpg_buf);
}