wrong display of slanted characters (on MS-Windows XP with official GNU Emacs v22.1)

wrong display of slanted characters (on MS-Windows XP with official GNU Emacs v22.1)

[Peter Tury]

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Hi,

I found that some slanted (italic) characters (especially `d') is
displayed in a wrong way sometimes: their upper right corner is
damaged _when I move the `point' from the position immediately after
them_.

I attach a picture about the problem: see the second d in the second line.

To reproduce the problem try this: run `runemacs -Q' > change to
fundamental mode > type  "d_x" > make the whole text slanted (M-o i) >
move point immediately after d (so cursor is on _): after a while (a
cursor blinking time?) d is damaged; the same happens if you move
point from the position immediately following d: either go up, down or
right. But if you move from other positions (e.g. from position
_before_ d, then d remains OK). This behavior seems to be independent
from cursor blinking.

Please fix this bug.

Thanks,
P

In GNU Emacs 22.1.1 (i386-mingw-nt5.1.2600)
 of 2007-06-02 on RELEASE
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Ic:/gnuwin32/include'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: ENU
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  encoded-kbd-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t

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Re: wrong display of slanted characters (on MS-Windows XP with official GNU Emacs v22.1)

[Juanma Barranquero]

On 6/22/07, Peter Tury <tury.peter@gmail.com> wrote:

> I found that some slanted (italic) characters (especially `d') is
> displayed in a wrong way sometimes: their upper right corner is
> damaged _when I move the `point' from the position immediately after
> them_.

>From etc/PROBLEMS:

When "ClearType" method is selected as the "method to smooth edges of
screen fonts" (in Display Properties, Appearance tab, under
"Effects"), there are various problems related to display of
characters: 2-pixel trace is left behind when moving overlays, bold
fonts can be hard to read, small portions of some characters could
appear chopped, etc.  This happens because, under ClearType,
characters are drawn outside their advertised bounding box.  Emacs 21
disabled the use of ClearType, whereas Emacs 22 allows it and has some
code to enlarge the width of the bounding box.  Apparently, this
display feature needs more changes to get it 100% right.  A workaround
is to disable ClearType.

Try disabling ClearType and seeing whether that helps. If so, it's a
known problem, not easy to fix.

             Juanma

Re: wrong display of slanted characters (on MS-Windows XP with official GNU Emacs v22.1)

[Peter Tury]

2007/6/22, Juanma Barranquero <lekktu@gmail.com>:

> From etc/PROBLEMS:
>
> When "ClearType" method is selected as the "method to smooth edges of
> screen fonts" (in Display Properties, Appearance tab, under
> "Effects"), there are various problems related to display of
> characters: 2-pixel trace is left behind when moving overlays, bold
> fonts can be hard to read, small portions of some characters could
> appear chopped, etc.  This happens because, under ClearType,
> characters are drawn outside their advertised bounding box.  Emacs 21
> disabled the use of ClearType, whereas Emacs 22 allows it and has some
> code to enlarge the width of the bounding box.  Apparently, this
> display feature needs more changes to get it 100% right.  A workaround
> is to disable ClearType.
>
> Try disabling ClearType and seeing whether that helps. If so, it's a
> known problem, not easy to fix.

Thanks for your quick response!
In fact I have "Standard" as "method to smooth edges of screen fonts".

Now I tried to check it off -- no change: I still see the same problem.

Also I tried to set it to "ClearType" --> the situation became much worse.

So I can reproduce the problem with "ClearType" what you cited above,
but the bug I reported seems to be another one.

Note that I can reproduce it only(?) when there is `_' (underscore?)
after `d'. Otherwise even slanted d is displayed well. So maybe the
problem is with `_'?

\bye
P

Re: wrong display of slanted characters (on MS-Windows XP with official GNU Emacs v22.1)

[Peter Tury]

2007/6/22, Peter Tury <tury.peter@gmail.com>:

> Note that I can reproduce it only(?) when there is `_' (underscore?)
> after `d'. Otherwise even slanted d is displayed well. So maybe the
> problem is with `_'?

Moreover it seems the problem is somewhere around screen refreshing,
since even slanted `d_' is displayed well if I move point from right
to left (through `d_') (e.g. via left arrow). I.e. if `d' is
redrawn(?) after `_', then everything is OK.

Also, if I change font size (e.g. from 10pt to 11pt) via
`mouse-set-font' (--> display is refreshed) or I switch to another
application (via alt+tab) whose window is over emacs' window and then
switch back to emacs (--> Emacs display is refreshed) then everything
is displayed well again ...

\bye
P

Re: wrong display of slanted characters (on MS-Windows XP with official GNU Emacs v22.1)

[Jason Rumney]

Peter Tury wrote:
> I found that some slanted (italic) characters (especially `d') is
> displayed in a wrong way sometimes: their upper right corner is
> damaged _when I move the `point' from the position immediately after
> them_.

This appears to be fixed in the new font backend for Emacs 23, though
there are other bugs with that code at the present time, so I cannot
recommend it as an interim solution yet.