加载不同格式类型图片封转函数（流中加载）

本文链接：https://blog.youkuaiyun.com/xuqiang918/article/details/8015340

本文详细介绍了在C++中初始化并从资源中加载不同格式的图片（如JPG、PNG）的方法，包括资源查找、内存分配、复制和创建流对象等步骤，并演示了如何将加载的图片进行贴图显示。

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定义各种图片变量

Gdiplus::Image *m_bgImg;
Gdiplus::Image *m_logoImg;
Gdiplus::Image *m_titleImg;
Gdiplus::Image *m_shutImg;
Gdiplus::Image *m_tvBg;
Gdiplus::Image *m_autoImg;
Gdiplus::Image *m_powerON;
Gdiplus::Image *m_powerONOver;

加载

int iResult = 0;

//加载资源图片
iResult += LoadImageFromResourceID( IDR_BG_JPG, RES_JPG, m_bgImg );

函数实现

//////////////////////////////////////////////////////////////////////////
//
// LoadImageFromResourceID 从资源中加载图片，然后从内存中创建Image对象
//
// 程序退出的时候需要手动删除pImg，释放资源
//
//////////////////////////////////////////////////////////////////////////
BOOL CMonitorSystemDlg::LoadImageFromResourceID( UINT nResID, UINT nResType, Gdiplus::Image* &pImg )
{
HRSRC hRes = NULL;

if ( nResType == RES_JPG )
{
hRes = FindResourceW( NULL, MAKEINTRESOURCEW( nResID ), L"JPG" );
}
if ( nResType == RES_PNG )
{
hRes = FindResourceW( NULL, MAKEINTRESOURCEW( nResID ), L"PNG" );
}

if ( NULL == hRes )
{
return FALSE;
}

DWORD dwSize = SizeofResource( NULL, hRes );

HGLOBAL hGlobal = LoadResource( NULL, hRes );
HGLOBAL hMem = GlobalAlloc( GMEM_FIXED | GMEM_MOVEABLE, dwSize );

if ( NULL == hMem )
{
return FALSE;
}

BYTE* lpRes = ( BYTE* )LockResource( hGlobal );
BYTE* lpMem = ( BYTE* )GlobalLock( hMem );

memcpy( lpMem, lpRes, dwSize );

IStream* pStream = NULL;

CreateStreamOnHGlobal( lpMem, TRUE, &pStream );

GlobalUnlock( hMem );

pImg = Image::FromStream( pStream );

pStream->Release();

return TRUE;
}

释放资源句柄

#define ReleasePtr( p ) { if ( p ){ delete p; p = NULL; }}

ReleasePtr( m_bgImg );

贴图方式显示

CDC* pDC = pDlg->GetDC();

  if ( hMemDC == NULL )
  {
   hMemDC = CreateCompatibleDC( pDC->m_hDC );
   hBitmap = CreateCompatibleBitmap( pDC->m_hDC, pDlg->m_rtFullScreen.Width(), pDlg->m_rtFullScreen.Height());
   SelectObject( hMemDC, hBitmap );
  }

Graphics graphics( hMemDC );

graphics.DrawImage( pDlg->m_bgImg, 0, 0, pDlg->m_rtBg.left, pDlg->m_rtBg.top, pDlg->m_rtBg.Width(), pDlg->m_rtBg.Height(), UnitPixel );

BitBlt( pDC->m_hDC, 0, 0, pDlg->m_rtFullScreen.Width(), pDlg->m_rtFullScreen.Height(), hMemDC, 0, 0, SRCCOPY );

pDlg->ReleaseDC( pDC );

注：资源释放很重要