[PATCH] emacs: Do not color non-matching authors by tag

[Michal Sojka <sojkam1@fel.cvut.cz>]

Customizing notmuch-search-line-faces to color lines in search result
according to tags has the effect that the color overrides other faces
set for the line. This is usually what the user wants with the
exception that it also colors non-matching authors and it is then not
possible to visually distinguish between matching and non-matching
authors.

This patch changes the way how are the faces specified in
notmuch-search-line-faces applied to the search results. In
particular, instead of adding an overlay for the whole line, the
existing faces of the line are replaced with what is given in
notmuch-search-line-faces. The only exception is that
notmuch-search-non-matching-authors face is never replaced.

Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>

---
 emacs/notmuch.el |   20 +++++++++++++++++---
 1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/emacs/notmuch.el b/emacs/notmuch.el
index 42619b2..d0fb834 100644
--- a/emacs/notmuch.el
+++ b/emacs/notmuch.el
@@ -593,17 +593,31 @@ matching will be applied."
   :type '(alist :key-type (string) :value-type (list))
   :group 'notmuch)
 
+(defun notmuch-search-set-line-face (start end face)
+  "Change face propery to value FACE expect for non-matching authors."
+  (save-excursion
+    (save-restriction
+      (narrow-to-region start end)
+      (goto-char (point-min))
+      (let ((fstart (point))
+	    fend)
+	(while (< fstart (point-max))
+	  (setq fend (or (next-single-property-change fstart 'face)
+			 (point-max)))
+	  (when (not (eq (get-text-property fstart 'face) 'notmuch-search-non-matching-authors))
+	    (put-text-property fstart fend 'face face))
+	  (setq fstart fend))))))
+
 (defun notmuch-search-color-line (start end line-tag-list)
   "Colorize lines in notmuch-show based on tags"
   (if notmuch-search-line-faces
-      (let ((overlay (make-overlay start end))
-	    (tags-faces (copy-alist notmuch-search-line-faces)))
+      (let ((tags-faces (copy-alist notmuch-search-line-faces)))
 	(while tags-faces
 	  (let* ((tag-face (car tags-faces))
 		 (tag (car tag-face))
 		 (face (cdr tag-face)))
 	    (cond ((member tag line-tag-list)
-		   (overlay-put overlay 'face face)
+		   (notmuch-search-set-line-face start end face)
 		   (setq tags-faces nil))
 		  (t
 		   (setq tags-faces (cdr tags-faces)))))))))
-- 
tg: (f117d80..) t/do-not-colorize-non-matching-authors-by-tag (depends on: master)