Parse percent values in CSS alpha components

* lisp/textmodes/css-mode.el (css--rgb-color): Support parsing percent
values in the alpha component.

* test/lisp/textmodes/css-mode-tests.el
(css-test-rgb-to-named-color-or-hex, css-test-rgb-parser): Update for
the above changes.

2 files changed, 14 insertions, 12 deletions

diff --git a/lisp/textmodes/css-mode.el b/lisp/textmodes/css-mode.el
index 1d13070f120..7e997ac2c0f 100644
--- a/lisp/textmodes/css-mode.el
+++ b/lisp/textmodes/css-mode.el
@@ -954,11 +954,11 @@ the returned hex string."
       (let* ((is-percent (match-beginning 1))
              (str (match-string (if is-percent 1 2)))
              (number (string-to-number str)))
-        (when is-percent
-          (setq number (* 255 (/ number 100.0))))
-        (if (and include-alpha (= iter 3))
-            (push (round (* number 255)) result)
-          (push (min (max 0 (truncate number)) 255) result))
+        (if is-percent
+            (setq number (* 255 (/ number 100.0)))
+          (when (and include-alpha (= iter 3))
+            (setq number (* number 255))))
+        (push (min (max 0 (round number)) 255) result)
         (goto-char (match-end 0))
         (css--color-skip-blanks)
         (cl-incf iter)
diff --git a/test/lisp/textmodes/css-mode-tests.el b/test/lisp/textmodes/css-mode-tests.el
index 537a88ec52b..272d281217e 100644
--- a/test/lisp/textmodes/css-mode-tests.el
+++ b/test/lisp/textmodes/css-mode-tests.el
@@ -293,7 +293,9 @@
                   ("rgb(255, 255, 255)" "white")
                   ("rgb(255, 255, 240)" "ivory")
                   ("rgb(18, 52, 86)" "#123456")
-                  ("rgba(18, 52, 86, 0.5)" "#12345680")))
+                  ("rgba(18, 52, 86, 0.5)" "#12345680")
+                  ("rgba(18, 52, 86, 50%)" "#12345680")
+                  ("rgba(50%, 50%, 50%, 50%)" "#80808080")))
     (with-temp-buffer
       (css-mode)
       (insert (nth 0 item))
@@ -330,11 +332,11 @@
 (ert-deftest css-test-rgb-parser ()
   (with-temp-buffer
     (css-mode)
-    (dolist (input '("255, 0, 127"
-                     "255, /* comment */ 0, 127"
-                     "255 0 127"
-                     "255, 0, 127, 0.75"
-                     "255 0 127 / 0.75"
+    (dolist (input '("255, 0, 128"
+                     "255, /* comment */ 0, 128"
+                     "255 0 128"
+                     "255, 0, 128, 0.75"
+                     "255 0 128 / 0.75"
                      "100%, 0%, 50%"
                      "100%, 0%, 50%, 0.115"
                      "100% 0% 50%"
@@ -342,7 +344,7 @@
       (erase-buffer)
       (save-excursion
         (insert input ")"))
-      (should (equal (css--rgb-color) "#ff007f")))))
+      (should (equal (css--rgb-color) "#ff0080")))))
 
 (ert-deftest css-test-hsl-parser ()
   (with-temp-buffer