* w32term.c:FONT_HEIGHT causes screen noise.
@ 2008-10-30 4:58 Kevin Yu
2008-11-26 13:43 ` Jason Rumney
0 siblings, 1 reply; 2+ messages in thread
From: Kevin Yu @ 2008-10-30 4:58 UTC (permalink / raw)
To: emacs-devel
Hi,
In function x_draw_glyph_string_backgound, the background of the
string will
be redrawn when FONT_HEIGHT(s->font) < s->height - 2 * box_line_width. The
macro FONT_HEIGHT is defined as: ((f)->height). When f->ascent + f->descent
< s->height but f->height >= s->height the background will never be redrawn. As
a result, you will find some display noise on the screen.
In w32font.c the f->height is calculated from tmHeight +
tmExternalLeading, so
f->ascent + f->descent < f->height if tmExternalLeading != 0. When
those fonts are
used as default font, you will find screen noise in *info* or
*Completions* buffers.
Because the spaces in those buffers use f->height as their height, and
tmExternalLeading number of pixels of text area will never be cleared.
This leaves
some screen noise in those buffers.
Best wishes.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: w32term.c:FONT_HEIGHT causes screen noise.
2008-10-30 4:58 w32term.c:FONT_HEIGHT causes screen noise Kevin Yu
@ 2008-11-26 13:43 ` Jason Rumney
0 siblings, 0 replies; 2+ messages in thread
From: Jason Rumney @ 2008-11-26 13:43 UTC (permalink / raw)
To: Kevin Yu; +Cc: emacs-devel
Kevin Yu wrote:
> In function x_draw_glyph_string_backgound, the background of the
> string will
> be redrawn when FONT_HEIGHT(s->font) < s->height - 2 * box_line_width. The
> macro FONT_HEIGHT is defined as: ((f)->height). When f->ascent + f->descent
> < s->height but f->height >= s->height the background will never be redrawn. As
> a result, you will find some display noise on the screen.
>
Thank you for your detailed analysis, I think I have fixed this now.
In future, please report such problems as bugs so they get properly tracked.
^ permalink raw reply [flat|nested] 2+ messages in thread
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