Picture Books

Books whose pages are pictures (scanned pages, comics as EPUB) are fitted to the screen.

EPUBs whose chapter files are pictures with next to no text (scanned pages, e.g. Diary of a Wimpy Kid: 385 x 625 JPEG per page) are recognized on opening (gzreader_picturebook.lua: sampled spine files, ≥ 70 % pictures-only; a book in fewer than 6 files, such as one big file between a cover and a contents page, is cut into 12 parts and the middle 10 are sampled instead). An EPUB converted from a PDF, whose pages are pictures with the text as separate lines between them, isn't one: fitting its pictures can't put the text back on the page. GZreader then adds a book style tweak (img { height: 100%; width: auto; max-width: 100% }, no margins/padding), sets the book's page margins to 0 and turns on smooth image scaling, keeping the old settings for when it's turned off (the quick panel → Fit pictures, in a book). Checked with the Kindle's own crengine.

100% is the page area between the top and bottom margins (ZenOS adds its title-bar height to the top margin), so pictures stay clear of the title bar and footer. 1.0.28 used 100vh, the whole screen: pages ran under the clock and the footer (crengine also split them, adding blank pages), and a wide picture capped at the screen width was stretched to full height. With 100% crengine keeps each picture's shape. The scans are only ~385 x 625, so they're enlarged about 1.3x to fill 800 pixels; that's why they look softer than real text. Smooth scaling makes them much less jagged.

Before fitting a book, GZreader measures its pictures once, in the background, to find the wide ones (a publisher's logo) and keep them at their own size; books recognized before their first open had this done then. Only one book is measured at a time: a second picture book opened (or Fit pictures tapped in it) while the first one is still being measured is fitted right after it. Until 2026-11-09's fix it was left as it was, and Fit pictures seemed to do nothing. When fitting has to wait for the measuring, a note says the pages will be fitted in a moment.