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Re: Confusing issue with redisplay
From: |
Eli Zaretskii |
Subject: |
Re: Confusing issue with redisplay |
Date: |
Thu, 19 Aug 2021 17:06:07 +0300 |
> From: Po Lu <luangruo@yahoo.com>
> Date: Thu, 19 Aug 2021 15:36:02 +0800
>
>
> I've run across an odd issue whilst bringing up a new window system: it
> seems that each glyph overlaps its surroundings by exactly one pixel,
> which leads to visible artifacting. For instance, while I would have
> expected the output from redisplay to be as follows:
>
> ["f" CHAR_GLYPH x=0 width=15 y=0 height=15] ["o" x=16 width=15 y=0
> height = 15]
>
> In this case "o" would actually start at 15 on the X axis, causing the
> glyph "f" to be partially overdrawn. What is even more confusing is
> that the output of redisplay seems to exhibit the same overlap under
> other window systems, whilst no artifacting is visible.
If "f" starts at 0 and its width is 15, then its last pixel is at
x=14, and the following glyph can start at x=15 without any overlap.
Or maybe you didn't tell enough details to understand what goes on
there.