1 files changed, 418 insertions, 197 deletions

diff --git a/lisp/window.el b/lisp/window.el
index 8b07ed462c9..c933996a72f 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -3703,7 +3703,7 @@ are one more than the actual value of these edges.  Note that if
 ABSOLUTE is non-nil, PIXELWISE is implicitly non-nil too."
   (let* ((window (window-normalize-window window body))
          (frame (window-frame window))
-         (border-width (frame-border-width frame))
+         (border-width (frame-internal-border-width frame))
          (char-width (frame-char-width frame))
          (char-height (frame-char-height frame))
          (left (if pixelwise
@@ -4572,12 +4572,13 @@ The function is called with one argument - a frame.
 Functions affected by this option are those that bury a buffer
 shown in a separate frame like `quit-window' and `bury-buffer'."
   :type '(choice (const :tag "Iconify" iconify-frame)
+                 (const :tag "Make invisible" make-frame-invisible)
                  (const :tag "Delete" delete-frame)
                  (const :tag "Do nothing" ignore)
                  function)
   :group 'windows
   :group 'frames
-  :version "24.1")
+  :version "26.1")
 
 (defun window--delete (&optional window dedicated-only kill)
   "Delete WINDOW if possible.
@@ -4595,7 +4596,9 @@ if WINDOW gets deleted or its frame is auto-hidden."
           (cond
            (kill
             (delete-frame frame))
-           ((functionp frame-auto-hide-function)
+           ((functionp (frame-parameter frame 'auto-hide-function))
+            (funcall (frame-parameter frame 'auto-hide-function)))
+           ((functionp frame-auto-hide-function)
             (funcall frame-auto-hide-function frame))))
         'frame)
        (deletable
@@ -6734,15 +6737,17 @@ live."
     window))
 
 (defun window--maybe-raise-frame (frame)
-  (let ((visible (frame-visible-p frame)))
-    (unless (or (not visible)
-                ;; Assume the selected frame is already visible enough.
-                (eq frame (selected-frame))
-                ;; Assume the frame from which we invoked the
-                ;; minibuffer is visible.
-                (and (minibuffer-window-active-p (selected-window))
-                     (eq frame (window-frame (minibuffer-selected-window)))))
-      (raise-frame frame))))
+  (make-frame-visible frame)
+  (unless (or (frame-parameter frame 'no-focus-on-map)
+              ;; Don't raise frames that should not get focus.
+              (frame-parameter frame 'no-accept-focus)
+              ;; Assume the selected frame is already visible enough.
+              (eq frame (selected-frame))
+              ;; Assume the frame from which we invoked the
+              ;; minibuffer is visible.
+              (and (minibuffer-window-active-p (selected-window))
+                   (eq frame (window-frame (minibuffer-selected-window)))))
+    (raise-frame frame)))
 
 ;; FIXME: Not implemented.
 ;; FIXME: By the way, there could be more levels of dedication:
@@ -6762,6 +6767,7 @@ The actual non-nil value of this variable will be copied to the
            (const display-buffer-pop-up-window)
            (const display-buffer-same-window)
            (const display-buffer-pop-up-frame)
+           (const display-buffer-in-child-frame)
            (const display-buffer-below-selected)
            (const display-buffer-at-bottom)
            (const display-buffer-in-previous-window)
@@ -6908,6 +6914,7 @@ Available action functions include:
  `display-buffer-same-window'
  `display-buffer-reuse-window'
  `display-buffer-pop-up-frame'
+ `display-buffer-in-child-frame'
  `display-buffer-pop-up-window'
  `display-buffer-in-previous-window'
  `display-buffer-use-some-window'
@@ -7239,6 +7246,7 @@ raising the frame."
                                  (get-largest-window frame t) alist)
                                 (window--try-to-split-window
                                  (get-lru-window frame t) alist))))
+
       (prog1 (window--display-buffer
               buffer window 'window alist display-buffer-mark-dedicated)
         (unless (cdr (assq 'inhibit-switch-frame alist))
@@ -7258,6 +7266,47 @@ again with `display-buffer-pop-up-window'."
       (and pop-up-windows
            (display-buffer-pop-up-window buffer alist))))
 
+(defun display-buffer-in-child-frame (buffer alist)
+  "Display BUFFER in a child frame.
+By default, this either reuses a child frame of the selected
+frame or makes a new child frame of the selected frame.  If
+successful, return the window used; otherwise return nil.
+
+If ALIST has a non-nil 'child-frame-parameters' entry, the
+corresponding value is an alist of frame parameters to give the
+new frame.  A 'parent-frame' parameter specifying the selected
+frame is provided by default.  If the child frame should be or
+become the child of any other frame, a corresponding entry must
+be added to ALIST."
+  (let* ((parameters
+          (append
+           (cdr (assq 'child-frame-parameters alist))
+           `((parent-frame . ,(selected-frame)))))
+         (parent (or (assq 'parent-frame parameters)
+                     (selected-frame)))
+         (share (assq 'share-child-frame parameters))
+         share1 frame window)
+    (with-current-buffer buffer
+      (when (frame-live-p parent)
+        (catch 'frame
+          (dolist (frame1 (frame-list))
+            (when (eq (frame-parent frame1) parent)
+              (setq share1 (assq 'share-child-frame
+                                 (frame-parameters frame1)))
+              (when (eq share share1)
+                (setq frame frame1)
+                (throw 'frame t))))))
+
+      (if frame
+          (setq window (frame-selected-window frame))
+        (setq frame (make-frame parameters))
+        (setq window (frame-selected-window frame))))
+
+    (prog1 (window--display-buffer
+            buffer window 'frame alist display-buffer-mark-dedicated)
+      (unless (cdr (assq 'inhibit-switch-frame alist))
+        (window--maybe-raise-frame frame)))))
+
 (defun display-buffer-below-selected (buffer alist)
   "Try displaying BUFFER in a window below the selected window.
 If there is a window below the selected one and that window
@@ -7272,7 +7321,8 @@ below the selected one, use that window."
         (and (not (frame-parameter nil 'unsplittable))
              (let ((split-height-threshold 0)
                    split-width-threshold)
-               (setq window (window--try-to-split-window (selected-window) alist)))
+               (setq window (window--try-to-split-window
+                             (selected-window) alist)))
              (window--display-buffer
               buffer window 'window alist display-buffer-mark-dedicated))
         (and (setq window (window-in-direction 'below))
@@ -7885,10 +7935,12 @@ See also `fit-frame-to-buffer-margins'."
 (declare-function x-display-pixel-height "xfns.c" (&optional terminal))
 
 (defun window--sanitize-margin (margin left right)
-  "Return MARGIN if it's a number between LEFT and RIGHT."
-  (when (and (numberp margin)
-             (<= left (- right margin)) (<= margin right))
-    margin))
+  "Return MARGIN if it's a number between LEFT and RIGHT.
+Return 0 otherwise."
+  (if (and (numberp margin)
+           (<= left (- right margin)) (<= margin right))
+      margin
+    0))
 
 (declare-function tool-bar-height "xdisp.c" (&optional frame pixelwise))
 
@@ -7906,190 +7958,197 @@ horizontally only.
 
 The new position and size of FRAME can be additionally determined
 by customizing the options `fit-frame-to-buffer-sizes' and
-`fit-frame-to-buffer-margins' or the corresponding parameters of
-FRAME."
+`fit-frame-to-buffer-margins' or setting the corresponding
+parameters of FRAME."
   (interactive)
-  (unless (and (fboundp 'x-display-pixel-height)
-               ;; We need the respective sizes now.
-               (fboundp 'display-monitor-attributes-list))
+  (unless (fboundp 'display-monitor-attributes-list)
     (user-error "Cannot resize frame in non-graphic Emacs"))
   (setq frame (window-normalize-frame frame))
   (when (window-live-p (frame-root-window frame))
-    (with-selected-window (frame-root-window frame)
-      (let* ((char-width (frame-char-width))
-             (char-height (frame-char-height))
-             (monitor-attributes (car (display-monitor-attributes-list
-                                       (frame-parameter frame 'display))))
-             (geometry (cdr (assq 'geometry monitor-attributes)))
-             (display-width (- (nth 2 geometry) (nth 0 geometry)))
-             (display-height (- (nth 3 geometry) (nth 1 geometry)))
-             (workarea (cdr (assq 'workarea monitor-attributes)))
-             ;; Handle margins.
-             (margins (or (frame-parameter frame 'fit-frame-to-buffer-margins)
-                          fit-frame-to-buffer-margins))
-             (left-margin (if (nth 0 margins)
-                              (or (window--sanitize-margin
-                                   (nth 0 margins) 0 display-width)
-                                  0)
-                            (nth 0 workarea)))
-             (top-margin (if (nth 1 margins)
-                             (or (window--sanitize-margin
-                                  (nth 1 margins) 0 display-height)
-                                 0)
-                           (nth 1 workarea)))
-             (workarea-width (nth 2 workarea))
-             (right-margin (if (nth 2 margins)
-                               (- display-width
-                                  (or (window--sanitize-margin
-                                       (nth 2 margins) left-margin display-width)
-                                      0))
-                             (nth 2 workarea)))
-             (workarea-height (nth 3 workarea))
-             (bottom-margin (if (nth 3 margins)
-                                (- display-height
-                                   (or (window--sanitize-margin
-                                        (nth 3 margins) top-margin display-height)
-                                       0))
-                              (nth 3 workarea)))
-             ;; The pixel width of FRAME (which does not include the
-             ;; window manager's decorations).
-             (frame-width (frame-pixel-width))
-             ;; The pixel width of the body of FRAME's root window.
-             (window-body-width (window-body-width nil t))
-             ;; The difference in pixels between total and body width of
-             ;; FRAME's window.
-             (window-extra-width (- (window-pixel-width) window-body-width))
-             ;; The difference in pixels between the frame's pixel width
-             ;; and the window's body width.  This is the space we can't
-             ;; use for fitting.
-             (extra-width (- frame-width window-body-width))
-             ;; The pixel position of FRAME's left border.  We usually
-             ;; try to leave this alone.
-             (left
-              (let ((left (frame-parameter nil 'left)))
-                (if (consp left)
-                    (funcall (car left) (cadr left))
-                  left)))
-             ;; The pixel height of FRAME (which does not include title
-             ;; line, decorations, and sometimes neither the menu nor
-             ;; the toolbar).
-             (frame-height (frame-pixel-height))
-             ;; The pixel height of FRAME's root window (we don't care
-             ;; about the window's body height since the return value of
-             ;; `window-text-pixel-size' includes header and mode line).
-             (window-height (window-pixel-height))
-             ;; The difference in pixels between the frame's pixel
-             ;; height and the window's height.
-             (extra-height (- frame-height window-height))
-             ;; The pixel position of FRAME's top border.
-             (top
-              (let ((top (frame-parameter nil 'top)))
-                (if (consp top)
-                    (funcall (car top) (cadr top))
-                  top)))
-             ;; Sanitize minimum and maximum sizes.
-             (sizes (or (frame-parameter frame 'fit-frame-to-buffer-sizes)
-                        fit-frame-to-buffer-sizes))
-             (max-height
-              (cond
-               ((numberp (nth 0 sizes)) (* (nth 0 sizes) char-height))
-               ((numberp max-height) (* max-height char-height))
-               (t display-height)))
-             (min-height
-              (cond
-               ((numberp (nth 1 sizes)) (* (nth 1 sizes) char-height))
-               ((numberp min-height) (* min-height char-height))
-               (t (* window-min-height char-height))))
-             (max-width
-              (cond
-               ((numberp (nth 2 sizes))
-                (- (* (nth 2 sizes) char-width) window-extra-width))
-               ((numberp max-width)
-                (- (* max-width char-width) window-extra-width))
-               (t display-width)))
-             (min-width
-              (cond
-               ((numberp (nth 3 sizes))
-                (- (* (nth 3 sizes) char-width) window-extra-width))
-               ((numberp min-width)
-                (- (* min-width char-width) window-extra-width))
-               (t (* window-min-width char-width))))
-             ;; Note: Currently, for a new frame the sizes of the header
-             ;; and mode line may be estimated incorrectly
-             (value (window-text-pixel-size
-                     nil t t workarea-width workarea-height t))
-             (width (+ (car value) (window-right-divider-width)))
-             (height
-              (+ (cdr value)
-                 (window-bottom-divider-width)
-                 (window-scroll-bar-height))))
-        ;; Don't change height or width when the window's size is fixed
-        ;; in either direction or ONLY forbids it.
-        (cond
-         ((or (eq window-size-fixed 'width) (eq only 'vertically))
-          (setq width nil))
-         ((or (eq window-size-fixed 'height) (eq only 'horizontally))
-          (setq height nil)))
-        ;; Fit width to constraints.
-        (when width
-          (unless frame-resize-pixelwise
-            ;; Round to character sizes.
-            (setq width (* (/ (+ width char-width -1) char-width)
-                           char-width)))
-          ;; Fit to maximum and minimum widths.
-          (setq width (max (min width max-width) min-width))
-          ;; Add extra width.
-          (setq width (+ width extra-width))
-          ;; Preserve margins.
-          (let ((right (+ left width)))
-            (cond
-             ((> right right-margin)
-              ;; Move frame to left (we don't know its real width).
-              (setq left (max left-margin (- left (- right right-margin)))))
-             ((< left left-margin)
-              ;; Move frame to right.
-              (setq left left-margin)))))
-        ;; Fit height to constraints.
-        (when height
-          (unless frame-resize-pixelwise
-            (setq height (* (/ (+ height char-height -1) char-height)
-                            char-height)))
-          ;; Fit to maximum and minimum heights.
-          (setq height (max (min height max-height) min-height))
-          ;; Add extra height.
-          (setq height (+ height extra-height))
-          ;; Preserve margins.
-          (let ((bottom (+ top height)))
-            (cond
-             ((> bottom bottom-margin)
-              ;; Move frame up (we don't know its real height).
-              (setq top (max top-margin (- top (- bottom bottom-margin)))))
-             ((< top top-margin)
-              ;; Move frame down.
-              (setq top top-margin)))))
-        ;; Apply changes.
-        (set-frame-position frame left top)
-        ;; Clumsily try to translate our calculations to what
-        ;; `set-frame-size' wants.
-        (when width
-          (setq width (- (+ (frame-text-width) width)
-                         extra-width window-body-width)))
-        (when height
-          (setq height (- (+ (frame-text-height) height)
-                          extra-height window-height)))
-        (set-frame-size
-         frame
-         (if width
-             (if frame-resize-pixelwise
-                 width
-               (/ width char-width))
-           (frame-text-width))
-         (if height
-             (if frame-resize-pixelwise
-                 height
-               (/ height char-height))
-           (frame-text-height))
-         frame-resize-pixelwise)))))
+    (let* ((char-width (frame-char-width frame))
+           (char-height (frame-char-height frame))
+           ;; WINDOW is FRAME's root window.
+           (window (frame-root-window frame))
+           (parent (frame-parent frame))
+           (monitor-attributes
+            (unless parent
+              (car (display-monitor-attributes-list
+                    (frame-parameter frame 'display)))))
+           ;; FRAME'S parent or display sizes.  Used in connection
+           ;; with margins.
+           (geometry
+            (unless parent
+              (cdr (assq 'geometry monitor-attributes))))
+           (parent-or-display-width
+            (if parent
+                (frame-native-width parent)
+              (- (nth 2 geometry) (nth 0 geometry))))
+           (parent-or-display-height
+            (if parent
+                (frame-native-height parent)
+              (- (nth 3 geometry) (nth 1 geometry))))
+           ;; FRAME'S parent or workarea sizes.  Used when no margins
+           ;; are specified.
+           (parent-or-workarea
+            (if parent
+                `(0 0 ,parent-or-display-width ,parent-or-display-height)
+              (cdr (assq 'workarea monitor-attributes))))
+           ;; The outer size of FRAME.  Needed to calculate the
+           ;; margins around the root window's body that have to
+           ;; remain untouched by fitting.
+           (outer-edges (frame-edges frame 'outer-edges))
+           (outer-width (if outer-edges
+                            (- (nth 2 outer-edges) (nth 0 outer-edges))
+                          ;; A poor guess.
+                          (frame-pixel-width frame)))
+           (outer-height (if outer-edges
+                             (- (nth 3 outer-edges) (nth 1 outer-edges))
+                           ;; Another poor guess.
+                           (frame-pixel-height frame)))
+           ;; The text size of of FRAME.  Needed to specify FRAME's
+           ;; text size after the root window's body's new sizes have
+           ;; been calculated.
+           (text-width (frame-text-width frame))
+           (text-height (frame-text-height frame))
+           ;; WINDOW's body size.
+           (body-width (window-body-width window t))
+           (body-height (window-body-height window t))
+           ;; The difference between FRAME's outer size and WINDOW's
+           ;; body size.
+           (outer-minus-body-width (- outer-width body-width))
+           (outer-minus-body-height (- outer-height body-height))
+           ;; The difference between FRAME's text size and WINDOW's
+           ;; body size (these values "should" be positive).
+           (text-minus-body-width (- text-width body-width))
+           (text-minus-body-height (- text-height body-height))
+           ;; The current position of FRAME.
+           (position (frame-position frame))
+           (left (car position))
+           (top (cdr position))
+           ;; The margins specified for FRAME.  These represent pixel
+           ;; offsets from the left, top, right and bottom edge of the
+           ;; display or FRAME's parent's native rectangle and have to
+           ;; take care of the display's taskbar and other obstacles.
+           ;; If they are unspecified, constrain the resulting frame
+           ;; to its workarea or the parent frame's native rectangle.
+           (margins (or (frame-parameter frame 'fit-frame-to-buffer-margins)
+                        fit-frame-to-buffer-margins))
+           ;; Convert margins intto pixel offsets from the left-top
+           ;; corner of FRAME's display or parent.
+           (left-margin (if (nth 0 margins)
+                            (window--sanitize-margin
+                             (nth 0 margins) 0 parent-or-display-width)
+                          (nth 0 parent-or-workarea)))
+           (top-margin (if (nth 1 margins)
+                           (window--sanitize-margin
+                            (nth 1 margins) 0 parent-or-display-height)
+                         (nth 1 parent-or-workarea)))
+           (right-margin (if (nth 2 margins)
+                             (- parent-or-display-width
+                                (window--sanitize-margin
+                                 (nth 2 margins) left-margin
+                                 parent-or-display-width))
+                           (nth 2 parent-or-workarea)))
+           (bottom-margin (if (nth 3 margins)
+                              (- parent-or-display-height
+                                 (window--sanitize-margin
+                                  (nth 3 margins) top-margin
+                                  parent-or-display-height))
+                            (nth 3 parent-or-workarea)))
+           ;; Minimum and maximum sizes specified for FRAME.
+           (sizes (or (frame-parameter frame 'fit-frame-to-buffer-sizes)
+                      fit-frame-to-buffer-sizes))
+           ;; Calculate the minimum and maximum pixel sizes of FRAME
+           ;; from the values provided by the MAX-HEIGHT, MIN-HEIGHT,
+           ;; MAX-WIDTH and MIN-WIDTH arguments or, if these are nil,
+           ;; from those provided by `fit-frame-to-buffer-sizes'.
+           (max-height
+            (min
+             (cond
+              ((numberp max-height) (* max-height char-height))
+              ((numberp (nth 0 sizes)) (* (nth 0 sizes) char-height))
+              (t parent-or-display-height))
+             ;; The following is the maximum height that fits into the
+             ;; top and bottom margins.
+             (max (- bottom-margin top-margin outer-minus-body-height))))
+           (min-height
+            (cond
+             ((numberp min-height) (* min-height char-height))
+             ((numberp (nth 1 sizes)) (* (nth 1 sizes) char-height))
+             (t (window-min-size window nil nil t))))
+           (max-width
+            (min
+             (cond
+              ((numberp max-width) (* max-width char-width))
+              ((numberp (nth 2 sizes)) (* (nth 2 sizes) char-width))
+              (t parent-or-display-width))
+             ;; The following is the maximum width that fits into the
+             ;; left and right margins.
+             (max (- right-margin left-margin outer-minus-body-width))))
+           (min-width
+            (cond
+             ((numberp min-width) (* min-width char-width))
+             ((numberp (nth 3 sizes)) (nth 3 sizes))
+             (t (window-min-size window t nil t))))
+           ;; Note: Currently, for a new frame the sizes of the header
+           ;; and mode line may be estimated incorrectly
+           (size
+            (window-text-pixel-size window t t max-width max-height))
+           (width (max (car size) min-width))
+           (height (max (cdr size) min-height)))
+      ;; Don't change height or width when the window's size is fixed
+      ;; in either direction or ONLY forbids it.
+      (cond
+       ((or (eq window-size-fixed 'width) (eq only 'vertically))
+        (setq width nil))
+       ((or (eq window-size-fixed 'height) (eq only 'horizontally))
+        (setq height nil)))
+      ;; Fit width to constraints.
+      (when width
+        (unless frame-resize-pixelwise
+          ;; Round to character sizes.
+          (setq width (* (/ (+ width char-width -1) char-width)
+                         char-width)))
+        ;; The new outer width (in pixels).
+        (setq outer-width (+ width outer-minus-body-width))
+        ;; Maybe move FRAME to preserve margins.
+        (let ((right (+ left outer-width)))
+          (cond
+           ((> right right-margin)
+            ;; Move frame to left.
+            (setq left (max left-margin (- left (- right right-margin)))))
+           ((< left left-margin)
+            ;; Move frame to right.
+            (setq left left-margin)))))
+      ;; Fit height to constraints.
+      (when height
+        (unless frame-resize-pixelwise
+          (setq height (* (/ (+ height char-height -1) char-height)
+                          char-height)))
+        ;; The new outer height.
+        (setq outer-height (+ height outer-minus-body-height))
+        ;; Preserve margins.
+        (let ((bottom (+ top outer-height)))
+          (cond
+           ((> bottom bottom-margin)
+            ;; Move frame up.
+            (setq top (max top-margin (- top (- bottom bottom-margin)))))
+           ((< top top-margin)
+            ;; Move frame down.
+            (setq top top-margin)))))
+      ;; Apply our changes.
+      (setq text-width
+            (if width
+                (+ width text-minus-body-width)
+              (frame-text-width frame)))
+      (setq text-height
+            (if height
+                (+ height text-minus-body-height)
+              (frame-text-height frame)))
+      (modify-frame-parameters
+       frame `((left . ,left) (top . ,top)
+               (width . (text-pixels . ,text-width))
+               (height . (text-pixels . ,text-height)))))))
 
 (defun fit-window-to-buffer (&optional window max-height min-height max-width min-width preserve-size)
   "Adjust size of WINDOW to display its buffer's contents exactly.
@@ -8286,6 +8345,168 @@ Return non-nil if the window was shrunk, nil otherwise."
   (when (and (window-combined-p window)
              (pos-visible-in-window-p (point-min) window))
     (fit-window-to-buffer window (window-total-height window))))
+
+(defun window-largest-empty-rectangle--maximums-1 (quad maximums)
+  "Support function for `window-largest-empty-rectangle'."
+  (cond
+   ((null maximums)
+    (list quad))
+   ((> (car quad) (caar maximums))
+    (cons quad maximums))
+   (t
+    (cons (car maximums)
+          (window-largest-empty-rectangle--maximums-1 quad (cdr maximums))))))
+
+(defun window-largest-empty-rectangle--maximums (quad maximums count)
+  "Support function for `window-largest-empty-rectangle'."
+  (setq maximums (window-largest-empty-rectangle--maximums-1 quad maximums))
+  (if (> (length maximums) count)
+      (nbutlast maximums)
+    maximums))
+
+(defun window-largest-empty-rectangle--disjoint-maximums (maximums count)
+  "Support function for `window-largest-empty-rectangle'."
+  (setq maximums (sort maximums (lambda (x y) (> (car x) (car y)))))
+  (let ((new-length 0)
+        new-maximums)
+    (while (and maximums (< new-length count))
+      (let* ((maximum (car maximums))
+             (at (nth 2 maximum))
+             (to (nth 3 maximum)))
+        (catch 'drop
+          (dolist (new-maximum new-maximums)
+            (let ((new-at (nth 2 new-maximum))
+                  (new-to (nth 3 new-maximum)))
+              (when (if (< at new-at) (> to new-at) (< at new-to))
+                ;; Intersection -> drop.
+                (throw 'drop nil))))
+          (setq new-maximums (cons maximum new-maximums))
+          (setq new-length (1+ new-length)))
+        (setq maximums (cdr maximums))))
+
+    (nreverse new-maximums)))
+
+(defun window-largest-empty-rectangle (&optional window count min-width min-height positions left)
+  "Return dimensions of largest empty rectangle in WINDOW.
+WINDOW must be a live window and defaults to the selected one.
+
+The return value is a triple of the width and the start and end
+Y-coordinates of the largest rectangle that can be inscribed into
+the empty space (the space not displaying any text) of WINDOW's
+text area.  The return value is nil if the current glyph matrix
+of WINDOW is not up-to-date.
+
+Optional argument COUNT, if non-nil, specifies the maximum number
+of rectangles to return.  This means that the return value is a
+list of triples specifying rectangles with the largest rectangle
+first.  COUNT can be also a cons cell whose car specifies the
+number of rectangles to return and whose cdr, if non-nil, states
+that all rectangles returned must be disjoint.
+
+Note that the right edge of any rectangle returned by this
+function is the right edge of WINDOW (the left edge if its buffer
+displays RTL text).
+
+Optional arguments MIN-WIDTH and MIN-HEIGHT, if non-nil, specify
+the minimum width and height of any rectangle returned.
+
+Optional argument POSITIONS, if non-nil, is a cons cell whose car
+specifies the uppermost and whose cdr specifies the lowermost
+pixel position that must be covered by any rectangle returned.
+Note that positions are counted from the start of the text area
+of WINDOW.
+
+Optional argument LEFT, if non-nil, means to return values suitable for
+buffers displaying right to left text."
+  ;; Process lines as returned by ‘window-lines-pixel-dimensions’.
+  ;; STACK is a stack that contains rows that have to be processed yet.
+  (let* ((window (window-normalize-window window t))
+         (disjoint (and (consp count) (cdr count)))
+         (count (or (and (numberp count) count)
+                    (and (consp count) (numberp (car count)) (car count))))
+         (rows (window-lines-pixel-dimensions window nil nil t t left))
+         (rows-at 0)
+         (max-size 0)
+         row stack stack-at stack-to
+         top top-width top-at top-to top-size
+         max-width max-at max-to maximums)
+    ;; ROWS-AT is the position where the first element of ROWS starts.
+    ;; STACK-AT is the position where the first element of STACK starts.
+    (while rows
+      (setq row (car rows))
+      (if (or (not stack) (>= (car row) (caar stack)))
+          (progn
+            (unless stack
+              (setq stack-at rows-at))
+            (setq stack (cons row stack))
+            ;; Set ROWS-AT to where the first element of ROWS ends
+            ;; which, after popping ROW, makes it the start position of
+            ;; the next ROW.
+            (setq rows-at (cdr row))
+            (setq rows (cdr rows)))
+        (setq top (car stack))
+        (setq stack (cdr stack))
+        (setq top-width (car top))
+        (setq top-at (if stack (cdar stack) stack-at))
+        (setq top-to (cdr top))
+        (setq top-size (* top-width (- top-to top-at)))
+        (unless (or (and min-width (< top-width min-width))
+                    (and min-height (< (- top-to top-at) min-height))
+                    (and positions
+                         (or (> top-at (car positions))
+                             (< top-to (cdr positions)))))
+          (if count
+              (if disjoint
+                  (setq maximums (cons (list top-size top-width top-at top-to)
+                                       maximums))
+                (setq maximums (window-largest-empty-rectangle--maximums
+                                (list top-size top-width top-at top-to)
+                                maximums count)))
+            (when (> top-size max-size)
+              (setq max-size top-size)
+              (setq max-width top-width)
+              (setq max-at top-at)
+              (setq max-to top-to))))
+        (if (and stack (> (caar stack) (car row)))
+            ;; Have new top element of stack include old top.
+            (setq stack (cons (cons (caar stack) (cdr top)) (cdr stack)))
+          ;; Move rows-at backwards to top-at.
+          (setq rows-at top-at))))
+
+    (when stack
+      ;; STACK-TO is the position where the stack ends.
+      (setq stack-to (cdar stack))
+      (while stack
+        (setq top (car stack))
+        (setq stack (cdr stack))
+        (setq top-width (car top))
+        (setq top-at (if stack (cdar stack) stack-at))
+        (setq top-size (* top-width (- stack-to top-at)))
+        (unless (or (and min-width (< top-width min-width))
+                    (and min-height (< (- stack-to top-at) min-height))
+                    (and positions
+                         (or (> top-at (car positions))
+                             (< stack-to (cdr positions)))))
+          (if count
+              (if disjoint
+                  (setq maximums (cons (list top-size top-width top-at stack-to)
+                                       maximums))
+                (setq maximums (window-largest-empty-rectangle--maximums
+                                (list top-size top-width top-at stack-to)
+                                maximums count)))
+            (when (> top-size max-size)
+              (setq max-size top-size)
+              (setq max-width top-width)
+              (setq max-at top-at)
+              (setq max-to stack-to))))))
+
+    (cond
+     (maximums
+      (if disjoint
+          (window-largest-empty-rectangle--disjoint-maximums maximums count)
+        maximums))
+     ((> max-size 0)
+      (list max-width max-at max-to)))))
 
 (defun kill-buffer-and-window ()
   "Kill the current buffer and delete the selected window."