git-blame: an Emacs minor mode to view file with git-blame output.

Here's another version of git-blame.el that automatically tries to
create a sensible list of colors to use for both light and dark
backgrounds.  Plus a few minor fixes.

To use:

  1) Load into emacs: M-x load-file RET git-blame.el RET
  2) Open a git-controlled file
  3) Blame: M-x git-blame-mode

Signed-off-by: Junio C Hamano <junkio@cox.net>

contrib/emacs/git-blame.el

@@ -0,0 +1,180 @@
+;;; git-blame.el
+;; David Kågedal <davidk@lysator.liu.se>
+;; Message-ID: <87iren2vqx.fsf@morpheus.local>
+
+(require 'cl)
+(defun color-scale (l)
+  (let* ((colors ())
+         r g b)
+    (setq r l)
+    (while r
+      (setq g l)
+      (while g
+        (setq b l)
+        (while b
+          (push (concat "#" (car r) (car g) (car b)) colors)
+          (pop b))
+        (pop g))
+      (pop r))
+    colors))
+
+(defvar git-blame-dark-colors
+  (color-scale '("00" "04" "08" "0c"
+                 "10" "14" "18" "1c"
+                 "20" "24" "28" "2c"
+                 "30" "34" "38" "3c")))
+
+(defvar git-blame-light-colors
+  (color-scale '("c0" "c4" "c8" "cc"
+                 "d0" "d4" "d8" "dc"
+                 "e0" "e4" "e8" "ec"
+                 "f0" "f4" "f8" "fc")))
+
+(defvar git-blame-ancient-color "dark green")
+
+(defvar git-blame-overlays nil)
+(defvar git-blame-cache nil)
+
+(defvar git-blame-mode nil)
+(make-variable-buffer-local 'git-blame-mode)
+(push (list 'git-blame-mode " blame") minor-mode-alist)
+
+(defun git-blame-mode (&optional arg)
+  (interactive "P")
+  (if arg
+      (setq git-blame-mode (eq arg 1))
+    (setq git-blame-mode (not git-blame-mode)))
+  (make-local-variable 'git-blame-overlays)
+  (make-local-variable 'git-blame-colors)
+  (make-local-variable 'git-blame-cache)
+  (let ((bgmode (cdr (assoc 'background-mode (frame-parameters)))))
+    (if (eq bgmode 'dark)
+        (setq git-blame-colors git-blame-dark-colors)
+      (setq git-blame-colors git-blame-light-colors)))
+  (if git-blame-mode
+      (git-blame-run)
+    (git-blame-cleanup)))
+
+(defun git-blame-run ()
+  (let* ((display-buf (current-buffer))
+         (blame-buf (get-buffer-create
+                     (concat " git blame for " (buffer-name))))
+         (proc (start-process "git-blame" blame-buf
+                             "git" "blame" "--incremental"
+                             (file-name-nondirectory buffer-file-name))))
+    (mapcar 'delete-overlay git-blame-overlays)
+    (setq git-blame-overlays nil)
+    (setq git-blame-cache (make-hash-table :test 'equal))
+    (with-current-buffer blame-buf
+      (erase-buffer)
+      (make-local-variable 'git-blame-file)
+      (make-local-variable 'git-blame-current)
+      (setq git-blame-file display-buf)
+      (setq git-blame-current nil))
+    (set-process-filter proc 'git-blame-filter)
+    (set-process-sentinel proc 'git-blame-sentinel)))
+
+(defun git-blame-cleanup ()
+  "Remove all blame properties"
+    (mapcar 'delete-overlay git-blame-overlays)
+    (setq git-blame-overlays nil)
+    (let ((modified (buffer-modified-p)))
+      (remove-text-properties (point-min) (point-max) '(point-entered nil))
+      (set-buffer-modified-p modified)))
+
+(defun git-blame-sentinel (proc status)
+  ;;(kill-buffer (process-buffer proc))
+  (message "git blame finished"))
+
+(defvar in-blame-filter nil)
+
+(defun git-blame-filter (proc str)
+  (save-excursion
+    (set-buffer (process-buffer proc))
+    (goto-char (process-mark proc))
+    (insert-before-markers str)
+    (goto-char 0)
+    (unless in-blame-filter
+      (let ((more t)
+            (in-blame-filter t))
+        (while more
+          (setq more (git-blame-parse)))))))
+
+(defun git-blame-parse ()
+  (cond ((looking-at "\\([0-9a-f]\\{40\\}\\) \\([0-9]+\\) \\([0-9]+\\) \\([0-9]+\\)\n")
+         (let ((hash (match-string 1))
+               (src-line (string-to-number (match-string 2)))
+               (res-line (string-to-number (match-string 3)))
+               (num-lines (string-to-number (match-string 4))))
+           (setq git-blame-current
+                 (git-blame-new-commit
+                  hash src-line res-line num-lines)))
+         (delete-region (point) (match-end 0))
+         t)
+        ((looking-at "filename \\(.+\\)\n")
+         (let ((filename (match-string 1)))
+           (git-blame-add-info "filename" filename))
+         (delete-region (point) (match-end 0))
+         t)
+        ((looking-at "\\([a-z-]+\\) \\(.+\\)\n")
+         (let ((key (match-string 1))
+               (value (match-string 2)))
+           (git-blame-add-info key value))
+         (delete-region (point) (match-end 0))
+         t)
+        ((looking-at "boundary\n")
+         (setq git-blame-current nil)
+         (delete-region (point) (match-end 0))
+         t)
+        (t
+         nil)))
+
+
+(defun git-blame-new-commit (hash src-line res-line num-lines)
+  (save-excursion
+    (set-buffer git-blame-file)
+    (let ((info (gethash hash git-blame-cache))
+          (inhibit-point-motion-hooks t))
+      (when (not info)
+        (let ((color (pop git-blame-colors)))
+          (unless color
+            (setq color git-blame-ancient-color))
+          (setq info (list hash src-line res-line num-lines
+                           (cons 'color color))))
+        (puthash hash info git-blame-cache))
+      (goto-line res-line)
+      (while (> num-lines 0)
+        (if (get-text-property (point) 'git-blame)
+            (forward-line)
+          (let* ((start (point))
+                 (end (progn (forward-line 1) (point)))
+                 (ovl (make-overlay start end)))
+            (push ovl git-blame-overlays)
+            (overlay-put ovl 'git-blame info)
+            (overlay-put ovl 'help-echo hash)
+            (overlay-put ovl 'face (list :background
+                                         (cdr (assq 'color (cddddr info)))))
+            ;;(overlay-put ovl 'point-entered
+            ;;             `(lambda (x y) (git-blame-identify ,hash)))
+            (let ((modified (buffer-modified-p)))
+              (put-text-property (if (= start 1) start (1- start)) (1- end)
+                                 'point-entered
+                                 `(lambda (x y) (git-blame-identify ,hash)))
+              (set-buffer-modified-p modified))))
+        (setq num-lines (1- num-lines))))))
+
+(defun git-blame-add-info (key value)
+  (if git-blame-current
+      (nconc git-blame-current (list (cons (intern key) value)))))
+
+(defun git-blame-current-commit ()
+  (let ((info (get-char-property (point) 'git-blame)))
+    (if info
+        (car info)
+      (error "No commit info"))))
+
+(defun git-blame-identify (&optional hash)
+  (interactive)
+  (shell-command
+   (format "git log -1 --pretty=oneline %s" (or hash
+                                                (git-blame-current-commit)))))