Re: Displaying scrollable images in a grid-layout

[Yuri Khan <yuri.v.khan@gmail.com>]

On Wed, Apr 15, 2015 at 8:37 AM, Eli Zaretskii <eliz@gnu.org> wrote:

> ??? Why does it make sense to show a partial line, when we can show it
> in its entirety?  Can you explain?

You assume that the line is a bigger unit than the image, that the
image is part of the line. However, in PDF viewers, an image of a
whole page contains many lines of text.

Many people, when confronted with a need to read documents in PDF
format, scroll the parts they have already read past the top window
edge, so that the window edge tracks where they are reading. This way,
if they are distracted, they can continue reading immediately without
having to find the last sentence they read.

The UI gesture for such reading mode is either mouse scrolling or
pressing the <down> arrow repeatedly or continuously. In both cases,
the reader wants scrolling to be as smooth as possible, ideally, with
each press or each wheel step scrolling by a constant number of
pixels. (Mouse scrolling may be further improved with acceleration,
but also based on pixels, not logical lines.)