Bitmap :: FromFile方法在x86上返回NULL [英] Bitmap::FromFile method returns NULL on x86

问题描述

我的这段代码在Windows 7 64位上运行：它允许我将 Image 的表示形式转换为 std :: string （ Base64EncodedImage ）到 GdiPlus :: Bitmap ：

  HRESULT hr; 
使用命名空间Gdiplus; 
 std :: string decodedImage = Base64EncodedImage; 
 DWORD imageSize = decodedImage.length（）; 
 
 HGLOBAL hMem = :: GlobalAlloc（GMEM_MOVEABLE，imageSize）; 
 if（！hMem）
 ErrorExit（TEXT（GlobalAlloc））; //http://msdn.microsoft.com/en-us/library/windows/desktop/ms682499(v=vs.85).aspx 
 
 LPVOID pImage = :: GlobalLock（hMem）; 
 if（！pImage）
 ErrorExit（TEXT（GlobalLock））; 
 
 CopyMemory（pImage，decodedImage.c_str（），imageSize）; 
 IStream * pStream = NULL; 
 
 BitmapData * bitmapData = new BitmapData; 
 if（:: CreateStreamOnHGlobal（hMem，FALSE，& pStream）！= S_OK）
 ErrorExit（TEXT（CreateStreamOnHGlobal））; 
 else 
 {
 bitmap = Bitmap :: FromStream（pStream）; //在WIN32 $ FAILS 
 if（！bitmap）
 ErrorExit（TEXT（FromStream））; 
 
 RECT clientRect; 
 GetClientRect（hwnd，& clientRect）; 
 
 bitmapClone = bitmap-> Clone（0，0，clientRect.right，clientRect.bottom，PixelFormatDontCare）; 
 delete bitmap; 
 bitmap = NULL; 
} 
  

但在Windows 7 32位上失败，特别是在这行： / p>

  bitmap = Bitmap :: FromStream（pStream）; 
  

它总是返回 NULL 得到这是如何工作在x64，但不是在x86。如果有人可以启发我，我会很感激。

谢谢！

解决方案>

但是当我评论了GDI +初始化时， Bitmap :: FromStream（pStream）方法总是返回 NULL 指针。

初始化？

  GdiplusStartupInput gdiplusStartupInput; 
 ULONG_PTR gdiplusToken; 
 //初始化GDI +。 
 GdiplusStartup（& gdiplusToken，& gdiplusStartupInput，NULL）; 
  

顺便说一下，GDI +未初始化：

  GdiplusShutdown（gdiplusToken）; 
  

I've this piece of code working on Windows 7 64-bit: it allows me to transform a representation of an Image contained into a std::string (Base64EncodedImage) to a GdiPlus::Bitmap:

HRESULT hr; 
using namespace Gdiplus;
std::string decodedImage = Base64EncodedImage;
DWORD imageSize = decodedImage.length();

HGLOBAL hMem = ::GlobalAlloc(GMEM_MOVEABLE, imageSize);
if (!hMem)
    ErrorExit(TEXT("GlobalAlloc")); //http://msdn.microsoft.com/en-us/library/windows/desktop/ms682499(v=vs.85).aspx

LPVOID pImage = ::GlobalLock(hMem);
if (!pImage)
    ErrorExit(TEXT("GlobalLock"));

CopyMemory(pImage, decodedImage.c_str(), imageSize);
IStream* pStream = NULL;

BitmapData* bitmapData = new BitmapData;
if (::CreateStreamOnHGlobal(hMem, FALSE, &pStream) != S_OK)
    ErrorExit(TEXT("CreateStreamOnHGlobal"));
else
{
    bitmap = Bitmap::FromStream(pStream);   //FAILS on WIN32
    if (!bitmap)
        ErrorExit(TEXT("FromStream"));

    RECT clientRect;
    GetClientRect(hwnd, &clientRect);

    bitmapClone = bitmap->Clone(0, 0, clientRect.right, clientRect.bottom, PixelFormatDontCare);
    delete bitmap;
    bitmap = NULL;    
}

But it fails on Windows 7 32-bit, specifically on this line:

bitmap = Bitmap::FromStream(pStream);

It always returns NULL, but I can't get how is this working on x64 but not in x86. If someone can enlighten me, I'll be grateful.

Thanks!

解决方案

The code you've provided works well for me.

But when I've commented the GDI+ initialization, the Bitmap::FromStream(pStream) method always returns NULL pointer.

Do you have the GDI+ initialization?

GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
// Initialize GDI+.
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

By the way, the GDI+ uninitialization:

GdiplusShutdown(gdiplusToken);

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