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Allow window-text-pixel-size to measure pixels around a position

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* doc/lispref/display.texi (Size of Displayed Text): Announce
new meaning of `from'.
* etc/NEWS: Announce changes.

* lisp/pixel-scroll.el (pixel-scroll-precision-scroll-up-page):
Use new feature.

* src/xdisp.c (window_text_pixel_size): Understand a special
format of `from' that specifies the amount of pixels above or
below a position.

(Fwindow_text_pixel_size): Update doc string.
This commit is contained in:
Po Lu 2021-12-23 09:12:02 +08:00
parent 2001ae5898
commit d54d8a88e9
4 changed files with 110 additions and 40 deletions
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22
doc/lispref/display.texi
View file

@ -2092,17 +2092,27 @@ pixels. @var{window} must be a live window and defaults to the
selected one. The return value is a cons of the maximum pixel-width
of any text line and the maximum pixel-height of all text lines. This
function exists to allow Lisp programs to adjust the dimensions of
@var{window} to the buffer text it needs to display.
@var{window} to the buffer text it needs to display, and for other
similar situations.
The return value can also optionally (see below) include the buffer
position of the first line whose dimensions were measured.
The optional argument @var{from}, if non-@code{nil}, specifies the
first text position to consider, and defaults to the minimum
accessible position of the buffer. If @var{from} is @code{t}, it
stands for the minimum accessible position that is not a newline
character. The optional argument @var{to}, if non-@code{nil},
specifies the last text position to consider, and defaults to the
maximum accessible position of the buffer. If @var{to} is @code{t},
it stands for the maximum accessible position that is not a newline
character.
character. If @var{from} is a cons, its @code{car} specifies a buffer
position, and its @code{cdr} specifies the vertical offset in pixels
from that position to the first screen line whose text is to be
measured. (The measurement will start from the visual beginning of
that screen line.) In that case, the return value will instead be a
list of the pixel-width, pixel-height, and the buffer position of the
first line that was measured. The optional argument @var{to}, if
non-@code{nil}, specifies the last text position to consider, and
defaults to the maximum accessible position of the buffer. If
@var{to} is @code{t}, it stands for the maximum accessible position
that is not a newline character.
The optional argument @var{x-limit}, if non-@code{nil}, specifies the
maximum X coordinate beyond which text should be ignored; it is

5
etc/NEWS
View file

@ -1011,6 +1011,11 @@ This controls whether or not the last screen line of the text being
measured will be counted for the purpose of calculating the text
dimensions.
+++
** 'window-text-pixel-size' understands a new meaning of 'from'.
Specifying a cons as the from argument allows to start measuring text
from a specified amount of pixels above or below a position.
** XDG support
*** New function 'xdg-state-home' returns 'XDG_STATE_HOME' environment variable.

34
lisp/pixel-scroll.el
View file

@ -516,22 +516,24 @@ the height of the current window."
usable-height))))
(goto-char up-point)))
(let ((current-vscroll (window-vscroll nil t)))
(if (<= delta current-vscroll)
(set-window-vscroll nil (- current-vscroll delta) t)
(setq delta (- delta current-vscroll))
(set-window-vscroll nil 0 t)
(while (> delta 0)
(let ((position (pixel-point-and-height-at-unseen-line)))
(unless (cdr position)
(signal 'beginning-of-buffer nil))
(set-window-start nil (car position) t)
;; If the line above is taller than the window height (i.e. there's
;; a very tall image), keep point on it.
(when (> (cdr position) usable-height)
(goto-char (car position)))
(setq delta (- delta (cdr position)))))
(when (< delta 0)
(set-window-vscroll nil (- delta) t))))))
(setq delta (- delta current-vscroll))
(set-window-vscroll nil 0 t)
(when (> delta 0)
(let* ((start (window-start))
(dims (window-text-pixel-size nil (cons start (- delta))
start nil nil nil t))
(height (nth 1 dims))
(position (nth 2 dims)))
(set-window-start nil position t)
;; If the line above is taller than the window height (i.e. there's
;; a very tall image), keep point on it.
(when (> height usable-height)
(goto-char position))
(when (or (not position) (eq position start))
(signal 'beginning-of-buffer nil))
(setq delta (- delta height))))
(when (< delta 0)
(set-window-vscroll nil (- delta) t)))))
(defun pixel-scroll-precision-interpolate (delta)
"Interpolate a scroll of DELTA pixels.

89
src/xdisp.c
View file

@ -10841,8 +10841,7 @@ window_text_pixel_size (Lisp_Object window, Lisp_Object from, Lisp_Object to,
ptrdiff_t start, end, bpos;
struct text_pos startp;
void *itdata = NULL;
int c, max_x = 0, max_y = 0, x = 0, y = 0;
int doff = 0;
int c, max_x = 0, max_y = 0, x = 0, y = 0, vertical_offset = 0, doff = 0;
if (NILP (from))
{
@ -10868,6 +10867,13 @@ window_text_pixel_size (Lisp_Object window, Lisp_Object from, Lisp_Object to,
break;
}
}
else if (CONSP (from))
{
start = clip_to_bounds (BEGV, fix_position (XCAR (from)), ZV);
bpos = CHAR_TO_BYTE (start);
CHECK_FIXNUM (XCDR (from));
vertical_offset = XFIXNUM (XCDR (from));
}
else
{
start = clip_to_bounds (BEGV, fix_position (from), ZV);
@ -10914,7 +10920,9 @@ window_text_pixel_size (Lisp_Object window, Lisp_Object from, Lisp_Object to,
itdata = bidi_shelve_cache ();
start_display (&it, w, startp);
int start_y = it.current_y;
/* It makes no sense to measure dimensions of region of text that
crosses the point where bidi reordering changes scan direction.
By using unidirectional movement here we at least support the use
@ -10923,13 +10931,50 @@ window_text_pixel_size (Lisp_Object window, Lisp_Object from, Lisp_Object to,
same directionality. */
it.bidi_p = false;
/* Start at the beginning of the line containing FROM. Otherwise
IT.current_x will be incorrectly set to zero at some arbitrary
non-zero X coordinate. */
reseat_at_previous_visible_line_start (&it);
it.current_x = it.hpos = 0;
if (IT_CHARPOS (it) != start)
move_it_to (&it, start, -1, -1, -1, MOVE_TO_POS);
if (vertical_offset != 0)
{
int last_y;
it.current_y = 0;
move_it_by_lines (&it, 0);
/* `move_it_vertically_backward' is called by move_it_vertically
to move by a negative value (upwards), but it is not always
guaranteed to leave the iterator at or above the position
given by the offset, which this loop ensures. */
if (vertical_offset < 0)
{
while (it.current_y > vertical_offset)
{
last_y = it.current_y;
move_it_vertically_backward (&it,
(abs (vertical_offset)
+ it.current_y));
if (it.current_y == last_y)
break;
}
}
else
{
move_it_vertically (&it, vertical_offset);
}
it.current_y = (WINDOW_TAB_LINE_HEIGHT (w)
+ WINDOW_HEADER_LINE_HEIGHT (w));
start = clip_to_bounds (BEGV, IT_CHARPOS (it), ZV);
start_y = it.current_y;
}
else
{
/* Start at the beginning of the line containing FROM. Otherwise
IT.current_x will be incorrectly set to zero at some arbitrary
non-zero X coordinate. */
reseat_at_previous_visible_line_start (&it);
it.current_x = it.hpos = 0;
if (IT_CHARPOS (it) != start)
move_it_to (&it, start, -1, -1, -1, MOVE_TO_POS);
}
/* Now move to TO. */
int start_x = it.current_x;
@ -11052,26 +11097,34 @@ window_text_pixel_size (Lisp_Object window, Lisp_Object from, Lisp_Object to,
bidi_unshelve_cache (itdata, false);
return Fcons (make_fixnum (x - start_x), make_fixnum (y));
return (!vertical_offset
? Fcons (make_fixnum (x - start_x), make_fixnum (y))
: list3i (x - start_x, y, start));
}
DEFUN ("window-text-pixel-size", Fwindow_text_pixel_size, Swindow_text_pixel_size, 0, 7, 0,
doc: /* Return the size of the text of WINDOW's buffer in pixels.
WINDOW must be a live window and defaults to the selected one. The
return value is a cons of the maximum pixel-width of any text line
and the pixel-height of all the text lines in the accessible portion
of buffer text.
return value is a cons of the maximum pixel-width of any text line and
the pixel-height of all the text lines in the accessible portion of
buffer text.
If FROM is a cons cell, the return value includes, in addition to the
dimensions, also a third element that provides the buffer position
from which measuring of the text dimensions was actually started.
This function exists to allow Lisp programs to adjust the dimensions
of WINDOW to the buffer text it needs to display.
The optional argument FROM, if non-nil, specifies the first text
position to consider, and defaults to the minimum accessible position
of the buffer. If FROM is t, it stands for the minimum accessible
position that starts a non-empty line. TO, if non-nil, specifies the
last text position and defaults to the maximum accessible position of
the buffer. If TO is t, it stands for the maximum accessible position
that ends a non-empty line.
of the buffer. If FROM is a cons, its car specifies a buffer
position, and its cdr specifies the vertical offset in pixels from
that position to the first screen line to be measured. If FROM is t,
it stands for the minimum accessible position that starts a non-empty
line. TO, if non-nil, specifies the last text position and defaults
to the maximum accessible position of the buffer. If TO is t, it
stands for the maximum accessible position that ends a non-empty line.
The optional argument X-LIMIT, if non-nil, specifies the maximum X
coordinate beyond which the text should be ignored. It is therefore