From: Aaron Jensen <aaronjensen@gmail.com>
Date: Sun, 10 Jan 2021 02:43:32 +0000 (-0600)
Subject: Fix 'window-text-pixel-size' when there are leading/trailing spaces
X-Git-Tag: emacs-28.0.90~4263
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=4dc72dd9deb1c3394ada3de3f52bc7c1ff831ab6;p=emacs.git

Fix 'window-text-pixel-size' when there are leading/trailing spaces

First, scan to find the first non-whitespace character and then
backtrack to find the beginning of the line.  The previous
algorithm always started on the non-whitespace character during
the backtrack, causing it to stop immediately and not actually
find the beginning of the line.  The same applies to the end of
line calculation.
* src/xdisp.c: (Fwindow_text_pixel_size): Fix off by one error.
(Bug#45748)

* test/src/xdisp-tests.el (xdisp-tests--window-text-pixel-size)
(xdisp-tests--window-text-pixel-size-leading-space)
(xdisp-tests--window-text-pixel-size-trailing-space): New tests.
---

diff --git a/src/xdisp.c b/src/xdisp.c
index 64f401690a6..ea67329cff1 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10649,9 +10649,10 @@ include the height of both, if present, in the return value.  */)
       bpos = BEGV_BYTE;
       while (bpos < ZV_BYTE)
 	{
-	  c = fetch_char_advance (&start, &bpos);
+	  c = FETCH_BYTE (bpos);
 	  if (!(c == ' ' || c == '\t' || c == '\n' || c == '\r'))
 	    break;
+	  inc_both (&start, &bpos);
 	}
       while (bpos > BEGV_BYTE)
 	{
@@ -10680,7 +10681,10 @@ include the height of both, if present, in the return value.  */)
 	  dec_both (&end, &bpos);
 	  c = FETCH_BYTE (bpos);
 	  if (!(c == ' ' || c == '\t' || c == '\n' || c == '\r'))
-	    break;
+            {
+	      inc_both (&end, &bpos);
+	      break;
+            }
 	}
       while (bpos < ZV_BYTE)
 	{
diff --git a/test/src/xdisp-tests.el b/test/src/xdisp-tests.el
index d13ce77a997..ec96d777ffb 100644
--- a/test/src/xdisp-tests.el
+++ b/test/src/xdisp-tests.el
@@ -72,4 +72,34 @@
     (should (equal (nth 0 posns) (nth 1 posns)))
     (should (equal (nth 1 posns) (nth 2 posns)))))
 
+(ert-deftest xdisp-tests--window-text-pixel-size () ;; bug#45748
+  (with-temp-buffer
+    (insert "xxx")
+    (let* ((window
+            (display-buffer (current-buffer) '(display-buffer-in-child-frame . nil)))
+          (char-width (frame-char-width))
+          (size (window-text-pixel-size nil t t)))
+      (delete-frame (window-frame window))
+      (should (equal (/ (car size) char-width) 3)))))
+
+(ert-deftest xdisp-tests--window-text-pixel-size-leading-space () ;; bug#45748
+  (with-temp-buffer
+    (insert " xx")
+    (let* ((window
+            (display-buffer (current-buffer) '(display-buffer-in-child-frame . nil)))
+          (char-width (frame-char-width))
+          (size (window-text-pixel-size nil t t)))
+      (delete-frame (window-frame window))
+      (should (equal (/ (car size) char-width) 3)))))
+
+(ert-deftest xdisp-tests--window-text-pixel-size-trailing-space () ;; bug#45748
+  (with-temp-buffer
+    (insert "xx ")
+    (let* ((window
+            (display-buffer (current-buffer) '(display-buffer-in-child-frame . nil)))
+          (char-width (frame-char-width))
+          (size (window-text-pixel-size nil t t)))
+      (delete-frame (window-frame window))
+      (should (equal (/ (car size) char-width) 3)))))
+
 ;;; xdisp-tests.el ends here