Add image size information to img elements to improve mobile performance and pagination

[ghost]

From gerar...@benespace.org on September 13, 2013 20:19:45

We can improve layout performance for HTML5 rendering engines, such as WebKit/Readium, by providing the rendering engine with image size information for elements. Without this information the rendering engine needs to load the image and calculate that information, which is expensive. We can also enable reading systems to implement deferred image loading, which improves performance and lower memory consumption. Pagination performance should also be improved.

So, we should take any element that lack height and width properties and add those with calculated values using a library, such as ImageMagick.

Original issue: http://code.google.com/p/daisy-pipeline/issues/detail?id=366

[bertfrees]

To do:

• check with reading system testers and/or Benetech whether this makes sense (@rdeltour)
• maybe just do this anyway because it is not much work

[josteinaj]

One thing to test and decide is which units to use for width/height, and how it affects small screens.