Lost frames after clonning

[opilarium]

I've found some wierd logic in clonning function of image:

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Image *CloneImage(...)
{
...
  if (detach == MagickFalse)
    clone_image->blob=ReferenceBlob(image->blob);
  else
    {
      clone_image->next=NewImageList();
      clone_image->previous=NewImageList();
      clone_image->blob=CloneBlobInfo((BlobInfo *) NULL);
    }

That means if an image has multiple pages they will be lost.
I think it's serious bug.

[magick]

Images are typically in a list and maintains its position in the list with the next and previous pointers. CloneImage() is behaving properly in that it typically makes a copy that is standalone to remove it from the list (i.e. an orphan), while leaving the original image in the list. You can set the detach parameter to ensure the clone maintains its position in list. Given that, what exactly is the bug you are reporting?

[opilarium]

I serialize an image using write method.

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// Write image to in-memory BLOB
void Magick::Image::write ( Blob *blob_ )
{
  modifyImage();

As listed above write invokes modifyImage.

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void Magick::Image::modifyImage( void )
{
  ...
  replaceImage( CloneImage( image(),
                            0, // columns
                            0, // rows
                            MagickTrue, // orphan
                            &exceptionInfo) );
  ...
}

If the image has it's copy previous and next pages will be lost.

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Magick::Image img1; // has 2 pages
Magick::Image img2( img1 ); // has 2 pages. img2 has ImageRef of img1

Magick::Blob blob;
img2.write( &blob ); // img2 has been detached and now has 1 page!

[dlemstra]

Magick::Image is always a single image. Take a look at the code that reads the image.

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void Magick::Image::read(MagickCore::Image *image,
  MagickCore::ExceptionInfo *exceptionInfo)
{
  ...
  // Destroy any extra image frames
  next=image->next;
  image->next=(MagickCore::Image *) NULL;
  next->previous=(MagickCore::Image *) NULL;
  DestroyImageList(next);
}

You should use the readImages method from STL.h if you want to read more than one frame.

[opilarium]

Magick::Image is always a single image.

Well. Than how does it work with multipage tiff file?

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Magick::Blob blob( buffer.get(), file_size );
img.read( blob );

img has multiple pages.

[dlemstra]

What do you mean by 'img has multiple pages?'. It will only contain the first page.

[opilarium]

I mean img has properly working img.next image. But I only have one.

[dlemstra]

Are you using the latest version of ImageMagick?

[opilarium]

No. 6.8.3. Is that an issue?

[dlemstra]

I am asking that because this might be something that was fixed in a later version. The image() property of an img should be NULL.

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Magick::Blob blob( buffer.get(), file_size );
img.read( blob );
if (img.image()->next == NULL) // This should be true...  

A Magick:Image instance should always contain a single image. It should be considered a bug if it contains more then one image.