Re: [GM-help] getting a page from a PDF with core

[Bob F. <bfr...@si...>]

On Sun, 17 Apr 2016, jc...@gm... wrote:

> Hi all,
>
> I'd like to open a PDF (or some other multi-page image type) with Core
> and get a specific page. I can append a [number] to the filename, of
> course, but I'd like to be able to do this with a memory buffer as
> well, where no filename is around, and it would "feel" better to do it
> with an int rather than setting a string.
>
> I found the ->scene member, which seems to be what Wand uses, but I
> can't get it to work. This test program seems to always render the
> whole PDF and then pick out page zero:

What you are wanting is 'subimage' and 'subrange' in ImageInfo. 
These need to be specified in the image_info struct which is passed to 
ReadImage.

subimage - Starting image scene ID to select
subrange - Span of image scene IDs (from starting scene) to select

I can't answer if ImageMagick still supports this interface.

In GraphicsMagick, the rather obtuse SetImageInfo() function sets 
these values based on what it finds in the image->filename field.

Bob
-- 
Bob Friesenhahn
bfr...@si..., http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/