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Make it work to pixel scroll by deltas larger than the window

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* lisp/pixel-scroll.el
(pixel-scroll-precision-scroll-down-page):
(pixel-scroll-precision-scroll-up-page): New functions.

(pixel-scroll-precision-scroll-up)
(pixel-scroll-precision-scroll-down): Make it safe to scroll
by deltas larger than the current window.
This commit is contained in:
Po Lu 2021-12-04 09:09:28 +08:00
parent 352c737dce
commit 1450fa16ed
1 changed files with 21 additions and 6 deletions
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27
lisp/pixel-scroll.el
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@ -401,10 +401,7 @@ Otherwise, redisplay will reset the window's vscroll."
(set-window-start nil (pixel-point-at-unseen-line) t)
(set-window-vscroll nil vscroll t))
;; FIXME: This doesn't work when DELTA is larger than the height
;; of the current window, and someone should probably fix that
;; at some point.
(defun pixel-scroll-precision-scroll-down (delta)
(defun pixel-scroll-precision-scroll-down-page (delta)
"Scroll the current window down by DELTA pixels.
Note that this function doesn't work if DELTA is larger than
the height of the current window."
@ -440,8 +437,18 @@ the height of the current window."
(set-window-start nil desired-start t))
(set-window-vscroll nil desired-vscroll t))))
(defun pixel-scroll-precision-scroll-up (delta)
"Scroll the current window up by DELTA pixels."
(defun pixel-scroll-precision-scroll-down (delta)
"Scroll the current window down by DELTA pixels."
(let ((max-height (window-text-height nil t)))
(while (> delta max-height)
(pixel-scroll-precision-scroll-down-page max-height)
(setq delta (- delta max-height)))
(pixel-scroll-precision-scroll-down-page delta)))
(defun pixel-scroll-precision-scroll-up-page (delta)
"Scroll the current window up by DELTA pixels.
Note that this function doesn't work if DELTA is larger than
the height of the current window."
(let* ((edges (window-edges nil t nil t))
(max-y (- (nth 3 edges)
(nth 1 edges)))
@ -490,6 +497,14 @@ the height of the current window."
(set-window-vscroll nil desired-vscroll t))
(set-window-vscroll nil (abs delta) t)))))))
(defun pixel-scroll-precision-scroll-up (delta)
"Scroll the current window up by DELTA pixels."
(let ((max-height (window-text-height nil t)))
(while (> delta max-height)
(pixel-scroll-precision-scroll-up-page max-height)
(setq delta (- delta max-height)))
(pixel-scroll-precision-scroll-up-page delta)))
;; FIXME: This doesn't _always_ work when there's an image above the
;; current line that is taller than the window, and scrolling can
;; sometimes be jumpy in that case.