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bug#16691: 24.3.50; emacs_backtrace.txt
From: |
Eli Zaretskii |
Subject: |
bug#16691: 24.3.50; emacs_backtrace.txt |
Date: |
Mon, 10 Feb 2014 19:42:46 +0200 |
> Date: Mon, 10 Feb 2014 09:14:33 +0100
> From: martin rudalics <rudalics@gmx.at>
> CC: lekktu@gmail.com, drew.adams@oracle.com, 16691@debbugs.gnu.org
>
> >> - int x, y: Where and how are these set for a particular row (including
> >> header- and mode-line) and when and how are these eventually consumed?
> >> This is the greatest mystery for me so far.
> >
> > They are assigned in display_line and display_string. Examples from
> > display_line:
> >
> > row->y = it->current_y;
>
> Does the value set here account for extra_line_spacing or is the latter
> (as I presume) handled separately?
The y-coordinate of the row does include the extra_line_spacing, it
must. More accurately, the next row gets its y coordinate increased
due to extra line spacing of the previous row.
We calculate the value inside PRODUCE_GLYPHS (which expands into a
call to x_produce_glyphs in a GUI session), and then enlarge
it->descent by the computed value. Then display_line, which calls
PRODUCE_GLYPHS, copies these values from 'struct it' to the glyph row,
updates row->height accordingly, and uses row->height to increment
row->y when it advances to the next row (see near the end of
display_line).
> > [...]
> > if (it->current_x - it->pixel_width < it->first_visible_x)
> > row->x = x - it->first_visible_x;
> >
> > Mode line and header line are generated from strings, so look in
> > display_mode_line and display_string.
>
> I tried that but never found anything useful there. I suppose the
> header line has current_y always set to 0. But the mode line?
The magic hides in init_iterator, which is called by display_mode_line:
/* Use one of the mode line rows of W's desired matrix if
appropriate. */
if (row == NULL)
{
if (base_face_id == MODE_LINE_FACE_ID
|| base_face_id == MODE_LINE_INACTIVE_FACE_ID)
row = MATRIX_MODE_LINE_ROW (w->desired_matrix);
else if (base_face_id == HEADER_LINE_FACE_ID)
row = MATRIX_HEADER_LINE_ROW (w->desired_matrix);
}
IOW, we rely on the fact that the header line is always the first row,
and the mode line is the last one.
> > Not sure what you mean by "consumed". Consumed by whom and for what
> > purposes?
>
> I suppose when exposing the window (another part of Emacs display which
> I don't understand yet). What would current_y else be used for?
Why are we suddenly talking about current_y? There's no such member
in the glyph_row structure.
If you meant row->y, then it is used in many different places,
including the display back-end, various redisplay optimizations (which
compare rows of current and desired matrices), functions that find
buffer/string positions that correspond to a mouse click, and move_it_*
functions which simulate display, to name just a few.
If you meant something else, please elaborate.
- bug#16691: 24.3.50; emacs_backtrace.txt, (continued)
- bug#16691: 24.3.50; emacs_backtrace.txt, martin rudalics, 2014/02/08
- bug#16691: 24.3.50; emacs_backtrace.txt, Eli Zaretskii, 2014/02/08
- bug#16691: 24.3.50; emacs_backtrace.txt, Glenn Morris, 2014/02/08
- bug#16691: 24.3.50; emacs_backtrace.txt, Eli Zaretskii, 2014/02/08
- bug#16691: 24.3.50; emacs_backtrace.txt, Glenn Morris, 2014/02/08
- bug#16691: 24.3.50; emacs_backtrace.txt, martin rudalics, 2014/02/09
- bug#16691: 24.3.50; emacs_backtrace.txt, Eli Zaretskii, 2014/02/09
- bug#16691: 24.3.50; emacs_backtrace.txt, martin rudalics, 2014/02/09
- bug#16691: 24.3.50; emacs_backtrace.txt, Eli Zaretskii, 2014/02/09
- bug#16691: 24.3.50; emacs_backtrace.txt, martin rudalics, 2014/02/10
- bug#16691: 24.3.50; emacs_backtrace.txt,
Eli Zaretskii <=
- bug#16691: 24.3.50; emacs_backtrace.txt, martin rudalics, 2014/02/10
- bug#16691: 24.3.50; emacs_backtrace.txt, Eli Zaretskii, 2014/02/10