Quote:
Originally Posted by ddavtian
Night mode is tricky for pdf documents. This format, by definition, should show the document as it was created. Ezpdf reader, another good one, has night mode but only in reflow mode (which usually doesn't work for my technical books).
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APV (which I'm one of the developers of) has several color modes for pdf documents that do nightmode. The simplest and fastest just reverses the colors. For your usual black on white document, that works, though photos look funny when reversed, since the colors change. Another version first converts to grayscale, then reverses. That avoids the weird colors. The version I use most of the time, even in daytime, converts to grayscale, then replaces the white-to-black range with a black-to-green range. Typical black on white documents show up as green on black. Photos of course will be a bit off, but the books I read are mostly text. (And of course there is red on black for when you want to maintain night vision.)
This is extremely easy to implement using Android's ColorMatrixColorFilter functionality. You just put the color transformation matrix in the paint object you pass to Canvas.drawBitmap() (if memory serves).