Package: emacs;
Reported by: Keith David Bershatsky <esq <at> lawlist.com>
Date: Tue, 23 Jan 2018 07:33:02 UTC
Severity: minor
Tags: wontfix
Done: Stefan Kangas <stefankangas <at> gmail.com>
Bug is archived. No further changes may be made.
Message #26 received at 30226 <at> debbugs.gnu.org (full text, mbox):
From: Keith David Bershatsky <esq <at> lawlist.com> To: Eli Zaretskii <eliz <at> gnu.org> Cc: 30226 <at> debbugs.gnu.org Subject: Re: bug#30226: Fixing it->pixel_width / it->current_x when tabs and line numbers. Date: Wed, 31 Jan 2018 00:03:09 -0800
Thank you, Eli, for teaching me how to mathematically calculate the pixel-width of the tab STRETCH in this example ["C-q TAB Hello-world" and w->hscroll >= 2]. Greatly appreciated! :)
A couple of additional questions whenever you have the time . . . .
I. In the context of this particular example ["C-q TAB Hello-world" and w->hscroll >= 2], we cannot calculate the _relative_ X by subtracting it.first_visible_x from it.current_x (as would generally be the case). Is there a better way to calculate the _relative_ X instead of keeping track of _every_ visual pixel-width to the left of the current _relative_ X that we are seeking?
(For example, pgrowx and dump_glyph_row both just keep track of the prior _relative_ X and they add the prior pixel-width to derive the current _relative_ X.)
II. In a slightly different fact pattern with two (2) consecutive tabs ["C-q TAB C-q TAB Hello-world" and w->hscroll >= 2], the tab STRETCH of the second tab _visually_ disappears and dump_glyph_row reports that its width is -1. Is there a way to programmatically know whether the tab STRETCH is -1 when we are using move_it_in_display_line_to?
The following are the results of two calls to the revised function bug-30226 using this new hypothetical with two (2) consecutive tabs. And, I added a printout of pgrowx when w->hscroll == 2.
A. This is the first (1st) time we call the revised bug-30226 [w->hscroll == 1]:
1. NOTHING
it.c (0)
w->hscroll (1)
it.hpos (0)
it.current_x (0)
it.pixel_width (0)
2. TAB CHARACTER
it.c (187)
w->hscroll (1)
it.hpos (0)
it.current_x (0)
it.pixel_width (7)
3. TAB STRETCH
it.c (9)
w->hscroll (1)
it.hpos (0)
it.current_x (7)
it.pixel_width (49)
4. TAB STRETCH
it.c (9)
w->hscroll (1)
it.hpos (4)
it.current_x (35)
it.pixel_width (42)
5. TAB CHARACTER
it.c (187)
w->hscroll (1)
it.hpos (5)
it.current_x (77)
it.pixel_width (7)
6. TAB STRETCH
it.c (9)
w->hscroll (1)
it.hpos (6)
it.current_x (84)
it.pixel_width (49)
7. TEXT
it.c (72)
w->hscroll (1)
it.hpos (7)
it.current_x (133)
it.pixel_width (7)
* * *
Row Start End Used oE><\CTZFesm X Y W H V A P
==============================================================================
12 455 468 19 111000110000 0 192 210 16 16 12 12
-1 -1 0
-1 -1
-1 -1
Glyph# Type Pos O W Code C Face LR
0 C -1 0 7 0x000020 29 00
1 C -1 0 7 0x000031 1 29 00
2 C -1 0 7 0x000033 3 29 00
3 C -1 0 7 0x000020 29 00
4 S 455 B 42 0x000000 31 00
5 C 456 B 7 0x0000bb . 32 00
6 S 456 B 49 0x000000 31 00
7 C 457 B 7 0x000048 H 0 00
8 C 458 B 7 0x000065 e 0 00
9 C 459 B 7 0x00006c l 0 00
10 C 460 B 7 0x00006c l 0 00
11 C 461 B 7 0x00006f o 0 00
12 C 462 B 7 0x00002d - 0 00
13 C 463 B 7 0x000077 w 0 00
14 C 464 B 7 0x00006f o 0 00
15 C 465 B 7 0x000072 r 0 00
16 C 466 B 7 0x00006c l 0 00
17 C 467 B 7 0x000064 d 0 00
18 C 0 0 7 0x000020 0 00
B. This is the second (2nd) time we call the revised bug-30226 [w->hscroll == 2]:
1. NOTHING
it.c (0)
w->hscroll (2)
it.hpos (0)
it.current_x (0)
it.pixel_width (0)
2. TAB CHARACTER
it.c (187)
w->hscroll (2)
it.hpos (0)
it.current_x (0)
it.pixel_width (7)
3. TAB STRETCH
it.c (9)
w->hscroll (2)
it.hpos (0)
it.current_x (7)
it.pixel_width (49)
4. TAB CHARACTER
it.c (187)
w->hscroll (2)
it.hpos (5)
it.current_x (84)
it.pixel_width (7)
5. TAB STRETCH
it.c (9)
w->hscroll (2)
it.hpos (6)
it.current_x (91)
it.pixel_width (35)
6. TEXT
it.c (72)
w->hscroll (2)
it.hpos (7)
it.current_x (126)
it.pixel_width (7)
* * *
Row Start End Used oE><\CTZFesm X Y W H V A P
==============================================================================
12 455 468 19 111000110000 0 192 153 16 16 12 12
-1 -1 0
-1 -1
-1 -1
Glyph# Type Pos O W Code C Face LR
0 C -1 0 7 0x000020 29 00
1 C -1 0 7 0x000031 1 29 00
2 C -1 0 7 0x000033 3 29 00
3 C -1 0 7 0x000020 29 00
4 S 455 B 35 0x000000 31 00
5 C 456 B 7 0x0000bb . 32 00
6 S 456 B -1 0x000000 31 00
7 C 457 B 7 0x000048 H 0 00
8 C 458 B 7 0x000065 e 0 00
9 C 459 B 7 0x00006c l 0 00
10 C 460 B 7 0x00006c l 0 00
11 C 461 B 7 0x00006f o 0 00
12 C 462 B 7 0x00002d - 0 00
13 C 463 B 7 0x000077 w 0 00
14 C 464 B 7 0x00006f o 0 00
15 C 465 B 7 0x000072 r 0 00
16 C 466 B 7 0x00006c l 0 00
17 C 467 B 7 0x000064 d 0 00
18 C 0 0 7 0x000020 0 00
PGROWX: pgrowx glyph_row
TEXT: 19 glyphs
0 0: CHAR[ ] pos=-1 blev=2,btyp=EN w=7 a+d=12+4 face=31 MB AVOID
1 7: CHAR[1] pos=-1 blev=2,btyp=EN w=7 a+d=12+4 face=31 MB AVOID
2 14: CHAR[4] pos=-1 blev=2,btyp=EN w=7 a+d=12+4 face=31 MB AVOID
3 21: CHAR[ ] pos=-1 blev=2,btyp=EN w=7 a+d=12+4 face=31 MB AVOID
4 28: STRETCH[16+12] pos=456 w=35 a+d=12+4 face=33 MB
5 63: CHAR[0xbb] pos=457 blev=0,btyp=L w=7 a+d=12+4 face=34 MB
6 70: STRETCH[16+12] pos=457 w=-1 a+d=12+4 face=33 MB
7 69: CHAR[H] pos=458 blev=0,btyp=L w=7 a+d=12+4 MB
8 76: CHAR[e] pos=459 blev=0,btyp=L w=7 a+d=12+4 MB
9 83: CHAR[l] pos=460 blev=0,btyp=L w=7 a+d=12+4 MB
10 90: CHAR[l] pos=461 blev=0,btyp=L w=7 a+d=12+4 MB
11 97: CHAR[o] pos=462 blev=0,btyp=L w=7 a+d=12+4 MB
12 104: CHAR[-] pos=463 blev=0,btyp=L w=7 a+d=12+4 MB
13 111: CHAR[w] pos=464 blev=0,btyp=L w=7 a+d=12+4 MB
14 118: CHAR[o] pos=465 blev=0,btyp=L w=7 a+d=12+4 MB
15 125: CHAR[r] pos=466 blev=0,btyp=L w=7 a+d=12+4 MB
16 132: CHAR[l] pos=467 blev=0,btyp=L w=7 a+d=12+4 MB
17 139: CHAR[d] pos=468 blev=0,btyp=L w=7 a+d=12+4 MB
18 146: CHAR[ ] pos=0 blev=0,btyp=B w=7 a+d=12+4 MB
DEFUN ("bug-30226", Fbug_30226, Sbug_30226, 0, 0, 0,
doc: /* Debug the pixel-width of a stretch tab. */)
(void)
{
Fscroll_left (make_number (1), Qnil);
struct window *w = decode_live_window (selected_window);
struct frame *f = XFRAME (w->frame);
struct it it;
void *itdata = bidi_shelve_cache ();
enum move_it_result rc = MOVE_X_REACHED;
struct text_pos start_text_position;
int count = 1;
int previous_char = 0;
int previous_x = 0;
/* ******************************************************************************
START DISPLAY -- w->start
****************************************************************************** */
/* Begin the journey at w->start. */
SET_TEXT_POS_FROM_MARKER (start_text_position, w->start);
start_display (&it, w, start_text_position);
struct face *face = FACE_FROM_ID (it.f, it.face_id);
struct font *font = face->font;
/* ******************************************************************************
GO TO THE BEGINNING OF THE CURRENT LINE.
****************************************************************************** */
/* Place the IT on the current line containing PT. */
int voffset = (WINDOW_HEADER_LINE_HEIGHT (w) > 0
&& w->output_cursor.vpos > 0)
? w->output_cursor.vpos - 1
: w->output_cursor.vpos;
if (voffset > 0)
move_it_by_lines (&it, voffset);
struct glyph_row *glyph_row = MATRIX_ROW (w->current_matrix, it.vpos);
/* ******************************************************************************
MOVE IT OVER EACH CHARACTER ON THE CURRENT LINE.
****************************************************************************** */
while (true)
{
if (ITERATOR_AT_END_OF_LINE_P (&it)
|| FETCH_BYTE (IT_BYTEPOS (it)) == '\n'
|| rc == MOVE_POS_MATCH_OR_ZV)
break;
/* ******************************************************************************
DUMP RELEVANT GLYPH INFORMATION
****************************************************************************** */
if (w->hscroll > 0)
{
int w_hscroll = w->hscroll;
fprintf (stderr, "\n%d. %s\n\
it.c (%d)\n\
w->hscroll (%d)\n\
it.hpos (%d) \n\
it.current_x (%d)\n\
it.pixel_width (%d)\n",
count,
(it.c == 0
? "NOTHING"
: it.c == 187
? "TAB CHARACTER"
: it.c == '\t'
? "TAB STRETCH"
: "TEXT"),
it.c,
w_hscroll,
it.hpos,
it.current_x,
it.pixel_width);
}
/* ******************************************************************************
MOVE IT -- INCREMENT == IT.PIXEL_WIDTH
****************************************************************************** */
previous_char = it.c;
previous_x = it.current_x;
rc = move_it_in_display_line_to (&it, ZV, it.current_x + it.pixel_width,
MOVE_TO_POS | MOVE_TO_X);
count = count + 1;
if (rc == MOVE_LINE_CONTINUED)
break;
if (it.current_x - it.first_visible_x + font->space_width >=
window_box_width (w, TEXT_AREA))
break;
}
/* ******************************************************************************
REDISPLAY AND DUMP_GLPYH_ROW
****************************************************************************** */
redisplay_internal ();
fprintf (stderr, "\n");
dump_glyph_row (glyph_row, it.vpos, 2);
bidi_unshelve_cache (itdata, false);
return Qnil;
}
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