Subject: bug#1005: Emacs 22.3 Windows Draw/Redraw Issues

From: "Ng, Andrew" <[email-masked]>
Date: Fri, 19 Sep 2008 14:00:05 -0400

I have come across various draw/redraw problems with Emacs on Windows,
particular since ClearType support was enabled. These problems annoyed
me sufficiently that I decided to fix them myself. I have tried to get
these fixes submitted previously, but with no success thus far.

I've included two test files that show some of these issues. If you run
a plain "emacs -Q" and load in "test.html" and then move the cursor
right over the text, you will see problems with the italic text as the
cursor is moved to the right. It's particularly noticeable on the 'W'
and 'H' characters.

Load in the "test.txt" file and you will notice the same problem with
italic text. If you shrink the Emacs window such that the buffer is 3
lines high and then page up and down, you will sometimes get a stray
pixel appear in the top left hand corner of the 'C' character.

The issues described above happen both with or without ClearType
enabled. Using a font such as "Lucida Console" with
"w32-enable-synthesized-fonts" enabled further highlights some of the
issues. The issues will vary depending on the font used.

I've included diffs for the files that I have modified based on the
current source from the "EMACS_22_BASE" branch. There are quite a few
changes, so I expect this won't be a straightforward submission, if it
is accepted. I have already signed and returned all appropriate
paperwork to allow my changes to be accepted.

Thanks.

Regards,

Andrew Ng