ImageMagick MagickAutoOrientImage

最近在用imageMagick 進行圖像處理，主要是lua ffi調用ImageMagick， 發現MagickAutoOrientImage在舊版本中不存在，目前可以確定的是這個函數在ImageMagick 6.8.9中才出現。

WandExport MagickBooleanType MagickAutoOrientImage(MagickWand *wand)
{

  Image
    *orient_image;

  assert(wand != (MagickWand *) NULL);
  assert(wand->signature == WandSignature);
  if (wand->debug != MagickFalse)
    (void) LogMagickEvent(WandEvent,GetMagickModule(),"%s",wand->name);
  if (wand->images == (Image *) NULL)
    ThrowWandException(WandError,"ContainsNoImages",wand->name);
  orient_image=AutoOrientImage(wand->images,wand->images->orientation,
    wand->exception);
  if (orient_image == (Image *) NULL)
    return(MagickFalse);
  ReplaceImageInList(&wand->images,orient_image);
  return(MagickTrue);
}

所以就要看AutoOrientImage的實現來手動實現

MagickExport Image *AutoOrientImage(const Image *image,
  const OrientationType orientation,ExceptionInfo *exception)
{
  Image
    *orient_image;

  assert(image != (const Image *) NULL);
  assert(image->signature == MagickSignature);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickSignature);
  orient_image=(Image *) NULL;
  switch(orientation)
  {
    case UndefinedOrientation:
    case TopLeftOrientation:
    default:
    {
      orient_image=CloneImage(image,0,0,MagickTrue,exception);
      break;
    }
    case TopRightOrientation:
    {
      orient_image=FlopImage(image,exception);
      break;
    }
    case BottomRightOrientation:
    {
      orient_image=RotateImage(image,180.0,exception);
      break;
    }
    case BottomLeftOrientation:
    {
      orient_image=FlipImage(image,exception);
      break;
    }
    case LeftTopOrientation:
    {
      orient_image=TransposeImage(image,exception);
      break;
    }
    case RightTopOrientation:
    {
      orient_image=RotateImage(image,90.0,exception);
      break;
    }
    case RightBottomOrientation:
    {
      orient_image=TransverseImage(image,exception);
      break;
    }
    case LeftBottomOrientation:
    {
      orient_image=RotateImage(image,270.0,exception);
      break;
    }
  }
  if (orient_image != (Image *) NULL)
    orient_image->orientation=TopLeftOrientation;
  return(orient_image);
}