Fixes for fitting windows and frames to their buffers (Bug#37563)

* lisp/window.el (window-default-font-height)
(window-default-line-height): New functions.
(fit-frame-to-buffer): Interpret values of MAX-HEIGHT and
MIN-HEIGHT arguments in terms of WINDOW's default line height
(Bug#37563).
(fit-window-to-buffer): Obey size restricting arguments even
when size of WINDOW's text does not change.  Do not
temporarily select WINDOW and perform height/width related
calculations if and only if WINDOW is accordingly combined.
Interpret values of MAX-HEIGHT and MIN-HEIGHT arguments in
terms of WINDOW's default line height.

1 files changed, 141 insertions, 111 deletions

diff --git a/lisp/window.el b/lisp/window.el
index d93ec0add67..fafb6f90ed5 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -8501,6 +8501,41 @@ WINDOW must be a live window and defaults to the selected one."
                              (eobp)
                              window))))
 
+(defun window-default-font-height (&optional window)
+  "Return height in pixels of WINDOW's default face font.
+WINDOW must be a live window and defaults to the selected one.
+
+The return value accounts for any remapping of the default face
+font on WINDOW's frame."
+  (let* ((window (window-normalize-window window t))
+         (frame (window-frame window))
+         (default-font (face-font 'default frame)))
+    (if (and (display-multi-font-p (frame-parameter frame 'display))
+             (not (string-equal (frame-parameter frame 'font) default-font)))
+        (aref (font-info default-font frame) 3)
+      (frame-char-height frame))))
+
+(defun window-default-line-height (&optional window)
+  "Return height in pixels of a text line in WINDOW.
+WINDOW must be a live window and defaults to the selected one.
+
+The return value includes any line spacing defined for WINDOW's
+buffer or frame and accounts for any remapping of the default
+face on WINDOW's frame."
+  (let* ((window (window-normalize-window window t))
+         (font-height (window-default-font-height window))
+         (frame (window-frame window))
+         (buffer (window-buffer window))
+         (space-height
+          (or (and (display-graphic-p frame)
+                   (or (buffer-local-value 'line-spacing buffer)
+                       (frame-parameter frame 'line-spacing)))
+              0)))
+    (+ font-height
+       (if (floatp space-height)
+           (truncate (* (frame-char-height frame) space-height))
+         space-height))))
+
 ;;; Resizing windows and frames to fit their contents exactly.
 (defcustom fit-window-to-buffer-horizontally nil
   "Non-nil means `fit-window-to-buffer' can resize windows horizontally.
@@ -8643,6 +8678,7 @@ parameters of FRAME."
            (char-height (frame-char-height frame))
            ;; WINDOW is FRAME's root window.
            (window (frame-root-window frame))
+           (line-height (window-default-line-height window))
            (parent (frame-parent frame))
            (monitor-attributes
             (unless parent
@@ -8739,16 +8775,16 @@ parameters of FRAME."
            (max-height
             (min
              (cond
-              ((numberp max-height) (* max-height char-height))
-              ((numberp (nth 0 sizes)) (* (nth 0 sizes) char-height))
+              ((numberp max-height) (* max-height line-height))
+              ((numberp (nth 0 sizes)) (* (nth 0 sizes) line-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))
+             ((numberp min-height) (* min-height line-height))
+             ((numberp (nth 1 sizes)) (* (nth 1 sizes) line-height))
              (t (window-min-size window nil nil t))))
            (max-width
             (min
@@ -8871,124 +8907,118 @@ accessible position."
          max-height min-height max-width min-width
          (and (memq fit-frame-to-buffer '(vertically horizontally))
               fit-frame-to-buffer)))
-    (with-selected-window window
-      (let* ((pixelwise window-resize-pixelwise)
-             (char-height (frame-char-height))
-             (char-width (frame-char-width))
-             (total-height (window-size window nil pixelwise))
-             (body-height (window-body-height window pixelwise))
-             (body-width (window-body-width window pixelwise))
-             (min-height
-              ;; Sanitize MIN-HEIGHT.
-              (if (numberp min-height)
-                  ;; Can't get smaller than `window-safe-min-height'.
-                  (max (if pixelwise
-                           (* char-height min-height)
-                         min-height)
-                       (if pixelwise
-                           (window-safe-min-pixel-height window)
-                         window-safe-min-height))
-                ;; Preserve header and mode line if present.
-                (max (if pixelwise
-                         (* char-height window-min-height)
-                       window-min-height)
-                     (window-min-size window nil window pixelwise))))
-             (max-height
-              ;; Sanitize MAX-HEIGHT.
-              (if (numberp max-height)
-                  (min
-                   (+ total-height
-                      (window-max-delta
-                       window nil window nil t nil pixelwise))
-                   (if pixelwise
-                       (* char-height max-height)
-                     max-height))
-                (+ total-height (window-max-delta
-                                 window nil window nil t nil pixelwise))))
-             height)
-        (cond
-         ;; If WINDOW is vertically combined, try to resize it
-         ;; vertically.
-         ((and (not (eq fit-window-to-buffer-horizontally 'only))
-               (not (window-size-fixed-p window 'preserved))
-               (window-combined-p))
+    (let* ((pixelwise window-resize-pixelwise)
+           (frame (window-frame window))
+           (char-height (frame-char-height frame)))
+      (cond
+       ;; If WINDOW is vertically combined, try to resize it
+       ;; vertically.
+       ((and (not (eq fit-window-to-buffer-horizontally 'only))
+             (not (window-size-fixed-p window 'preserved))
+             (window-combined-p))
+        (let* ((line-height (window-default-line-height window))
+               (total-height (window-size window nil pixelwise))
+               (min-height
+                ;; Sanitize MIN-HEIGHT.
+                (if (numberp min-height)
+                    ;; Can't get smaller than `window-safe-min-height'.
+                    (max (if pixelwise
+                             (* line-height min-height)
+                           min-height)
+                         (if pixelwise
+                             (window-safe-min-pixel-height window)
+                           window-safe-min-height))
+                  ;; Preserve header and mode line if present.
+                  (max (if pixelwise
+                           (* line-height window-min-height)
+                         window-min-height)
+                       (window-min-size window nil window pixelwise))))
+               (max-height
+                ;; Sanitize MAX-HEIGHT.
+                (if (numberp max-height)
+                    (min
+                     (+ total-height
+                        (window-max-delta
+                         window nil window nil t nil pixelwise))
+                     (if pixelwise
+                         (* line-height max-height)
+                       (/ (* line-height max-height) line-height)))
+                  (+ total-height (window-max-delta
+                                   window nil window nil t nil pixelwise))))
+               (height (+ (cdr (window-text-pixel-size
+                                window nil t nil (frame-pixel-height frame) t))
+                          (window-scroll-bar-height window)
+                          (window-bottom-divider-width window))))
           ;; Vertically we always want to fit the entire buffer.
           ;; WINDOW'S height can't get larger than its frame's pixel
           ;; height.  Its width remains fixed.
-          (setq height (+ (cdr (window-text-pixel-size
-                                nil nil t nil (frame-pixel-height) t))
-                          (window-scroll-bar-height window)
-                          (window-bottom-divider-width)))
           ;; Round height.
           (unless pixelwise
             (setq height (/ (+ height char-height -1) char-height)))
+          (setq height (max min-height (min max-height height)))
           (unless (= height total-height)
             (window-preserve-size window)
             (window-resize-no-error
-             window
-             (- (max min-height (min max-height height)) total-height)
-             nil window pixelwise)
+             window (- height total-height) nil window pixelwise)
             (when preserve-size
-              (window-preserve-size window nil t))))
-         ;; If WINDOW is horizontally combined, try to resize it
-         ;; horizontally.
-         ((and fit-window-to-buffer-horizontally
-               (not (window-size-fixed-p window t 'preserved))
-               (window-combined-p nil t))
-          (let* ((total-width (window-size window t pixelwise))
-                 (min-width
-                  ;; Sanitize MIN-WIDTH.
-                  (if (numberp min-width)
-                      ;; Can't get smaller than `window-safe-min-width'.
-                      (max (if pixelwise
-                               (* char-width min-width)
-                             min-width)
-                           (if pixelwise
-                               (window-safe-min-pixel-width)
-                             window-safe-min-width))
-                    ;; Preserve fringes, margins, scrollbars if present.
+              (window-preserve-size window nil t)))))
+       ;; If WINDOW is horizontally combined, try to resize it
+       ;; horizontally.
+       ((and fit-window-to-buffer-horizontally
+             (not (window-size-fixed-p window t 'preserved))
+             (window-combined-p window t))
+        (let* ((char-width (frame-char-width frame))
+               (total-width (window-size window t pixelwise))
+               (min-width
+                ;; Sanitize MIN-WIDTH.
+                (if (numberp min-width)
+                    ;; Can't get smaller than `window-safe-min-width'.
                     (max (if pixelwise
-                             (* char-width window-min-width)
-                           window-min-width)
-                         (window-min-size nil nil window pixelwise))))
-                 (max-width
-                  ;; Sanitize MAX-WIDTH.
-                  (if (numberp max-width)
-                      (min (+ total-width
-                              (window-max-delta
-                               window t window nil t nil pixelwise))
-                           (if pixelwise
-                               (* char-width max-width)
-                             max-width))
-                    (+ total-width (window-max-delta
-                                    window t window nil t nil pixelwise))))
-                 ;; When fitting horizontally, assume that WINDOW's
-                 ;; start position remains unaltered.  WINDOW can't get
-                 ;; wider than its frame's pixel width, its height
-                 ;; remains unaltered.
-                 (width (+ (car (window-text-pixel-size
-                                 nil (window-start) (point-max)
-                                 (frame-pixel-width)
-                                 ;; Add one char-height to assure that
-                                 ;; we're on the safe side.  This
-                                 ;; overshoots when the first line below
-                                 ;; the bottom is wider than the window.
-                                 (* body-height
-                                    (if pixelwise 1 char-height))))
-                           (window-right-divider-width))))
-            (unless pixelwise
-              (setq width (/ (+ width char-width -1) char-width)))
-            (unless (= width body-width)
-              (window-preserve-size window t)
-              (window-resize-no-error
-               window
-               (- (max min-width
-                       (min max-width
-                            (+ total-width (- width body-width))))
-                  total-width)
-               t window pixelwise)
-              (when preserve-size
-                (window-preserve-size window t t))))))))))
+                             (* char-width min-width)
+                           min-width)
+                         (if pixelwise
+                             (window-safe-min-pixel-width window)
+                           window-safe-min-width))
+                  ;; Preserve fringes, margins, scrollbars if present.
+                  (max (if pixelwise
+                           (* char-width window-min-width)
+                         window-min-width)
+                       (window-min-size window nil window pixelwise))))
+               (max-width
+                ;; Sanitize MAX-WIDTH.
+                (if (numberp max-width)
+                    (min (+ total-width
+                            (window-max-delta
+                             window t window nil t nil pixelwise))
+                         (if pixelwise
+                             (* char-width max-width)
+                           max-width))
+                  (+ total-width (window-max-delta
+                                  window t window nil t nil pixelwise))))
+               ;; When fitting horizontally, assume that WINDOW's
+               ;; start position remains unaltered.  WINDOW can't get
+               ;; wider than its frame's pixel width, its height
+               ;; remains unaltered.
+               (width (+ (car (window-text-pixel-size
+                               window (window-start) (point-max)
+                               (frame-pixel-width)
+                               ;; Add one line-height to assure that
+                               ;; we're on the safe side.  This
+                               ;; overshoots when the first line below
+                               ;; the bottom is wider than the window.
+                               (* (window-body-height window pixelwise)
+                                  (if pixelwise 1 char-height))))
+                         (- total-width
+                            (window-body-width window pixelwise)))))
+          (unless pixelwise
+            (setq width (/ (+ width char-width -1) char-width)))
+          (setq width (max min-width (min max-width width)))
+          (unless (= width total-width)
+            (window-preserve-size window t)
+            (window-resize-no-error
+             window (- width total-width) t window pixelwise)
+            (when preserve-size
+              (window-preserve-size window t t)))))))))
 
 (defun window-safely-shrinkable-p (&optional window)
   "Return t if WINDOW can be shrunk without shrinking other windows.