Thanks for reply.

Yes, frames should actually be renamed to something more generic (array 
element? page? resourceCount? - i couldn’t find the right name yet). Actually, 
DDS doesn’t support animation, but it supports texture arrays which should be 
implemented using "frames".

I didn’t think about reading pdf files as an image, but why not… Thumbnails 
seems pretty close to mipmaps. Can there be multiple thumbnails of the 
different size for a page?

Иван Комиссаров

19 мая 2015 г., в 21:12, Rutledge Shawn <[email protected]> 
написал(а):

> I think the new API should have multi-page support.  It would be useful for 
> pdf, djvu, multi-page tiff, and for looking at individual frames of animated 
> gif, png, etc., to the extent that we write plugins for those.
> 
> I wrote a QQuickImageProvider for PDF (using poppler), but requestImage takes 
> only an “id” string to identify the image.  So I had to make up a composite 
> id containing both the filename and the page number.  (much like a URL format 
> would be, if you had to request multiple pages from a web server)  So that’s 
> the next API that needs to have some support for paging.
> 
> Can “frame” be considered the same as “page”?  But I see that you also have a 
> subimage concept in mind.
> 
> Sometimes (as in icon files, or in any kind of file that also includes a 
> smaller preview image) the sub images would be the same thing at different 
> resolution, right?  That is orthogonal to the idea of paging: a PDF file can 
> have multiple pages, and also embedded thumbnails for each page.  In order 
> for an image format plugin to be enough to write a PDF reader application, it 
> would need to support paging, and also getting the thumbnails for the pages.
> 
> In QQuickImageProvider::requestImage, requestedSize can also be given.  So 
> that’s one way to specify a thumbnail: if the available thumbnail is near 
> enough to requestedSize, return that instead.  The API anyway does not 
> guarantee that you get exactly the size that you ask for.
> 
> Eventually we could get to the point that a plain Image in QML could be used 
> as a PDF viewer, all by itself.  It would also need a paging API.
> 
> 
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