show git diff with color in Emacs

git.el

(defun git-diff ()
  (interactive)
  (let ((filename (buffer-file-name (current-buffer)))
        (git-buf "*my/git*"))
    (if (get-buffer git-buf)
        (kill-buffer git-buf))
    (with-current-buffer (get-buffer-create git-buf)
      (setq buffer-read-only nil)
      (erase-buffer)
      (call-process "git" nil t nil "diff" filename)
      (goto-char (point-min))
      (while (re-search-forward "^\\(\\(\\+\\)[^+]\\|\\(-\\)[^-]\\)" nil t)
        (let ((cur-point (or (match-beginning 2) (match-beginning 3)))
              (color (if (match-beginning 2)
                         "green"
                       "deep pink")))
          (end-of-line)
          (add-text-properties cur-point (point)
                               `(face ((foreground-color . ,color))))))
      (goto-char (point-min))
      (while (re-search-forward "^\\(\\+\\+\\+\\|---\\)" nil t)
        (let ((cur-point (match-beginning 1)))
          (end-of-line)
          (add-text-properties cur-point (point)
                               '(face ((weight . bold))))))
      (goto-char (point-min))
      (setq buffer-read-only t))
  (pop-to-buffer git-buf)
  (view-mode)))

(push '("*my/git*" :height 20) popwin:special-display-config)