Simplified image display.

Emacs now remembers the directory that Racket put the last image in.
It leaves up to 10 previously viewed images in this directory,
providing an 'image history'.

This also reduces memory requirements; emacs no longer reads image
content into memory.

1 files changed, 43 insertions, 35 deletions

diff --git a/elisp/geiser-repl.el b/elisp/geiser-repl.el
index 358359e..704a7fb 100644
--- a/elisp/geiser-repl.el
+++ b/elisp/geiser-repl.el
@@ -124,6 +124,11 @@ If you have a slow system, try to increase this time."
    :type 'string
    :group 'geiser-repl)
 
+(geiser-custom--defcustom geiser-image-cache-keep-last 10
+   "How many images to keep in geiser's image cache."
+   :type 'integer
+   :group 'geiser-repl)
+
 (geiser-custom--defface repl-input
   'comint-highlight-input geiser-repl "evaluated input highlighting")
 
@@ -277,8 +282,27 @@ module command as a string")
                                         (geiser-repl--host)
                                         (geiser-repl--port)))))
 
-(defvar geiser-repl--last-image nil)
-(defvar geiser-repl--last-image-filename nil)
+(defvar geiser-image-cache-dir nil)
+;; XXX make this a parameter from Racket...
+
+(defun geiser-repl--list-image-cache ()
+  "List all the images in the image cache."
+  (and geiser-image-cache-dir
+       (file-directory-p geiser-image-cache-dir)
+       (let ((files (directory-files-and-attributes
+                     geiser-image-cache-dir t "geiser-img-[0-9]*.png")))
+         (mapcar 'car
+                 (sort files '(lambda (a b)
+                                (< (float-time (nth 6 a))
+                                   (float-time (nth 6 b)))))))))
+
+(defun geiser-repl--clean-image-cache ()
+  "Clean all except for the last `geiser-image-cache-keep-last'
+images in 'geiser-image-cache-dir'."
+  (interactive)
+    (dolist (file (butlast (geiser-repl--list-image-cache)
+                           geiser-image-cache-keep-last))
+      (delete-file file)))
 
 (defun geiser-repl--replace-images ()
   "Replace all image patterns with actual images"
@@ -290,44 +314,28 @@ module command as a string")
         ;; not display it before it gets deleted (race condition)
         (let* ((file (match-string 1))
                (begin (match-beginning 0))
-               (end (match-end 0))
-               (imgdata (save-excursion
-                          (with-temp-buffer
-                            (set-buffer-multibyte nil)
-                            (insert-file-contents-literally file nil)
-                            (buffer-string)))))
+               (end (match-end 0)))
           (delete-region begin end)
           (if (and geiser-repl-inline-images (display-images-p))
-            (put-image (create-image imgdata nil t) begin "[image]")
+            (put-image (create-image file) begin "[image]")
             (progn
               (goto-char begin)
               (insert "[image] ; use M-x geiser-view-last-image to view")))
-          (delete-file file)
-          ; XXX need to ensure that the file is in the temporary
-          ; folder before deleting it. Racket will only generate files
-          ; in the system temporary folder (/var/tmp), but we don't
-          ; know what the temp. folder is, especially on Windows
-          (setq geiser-repl--last-image imgdata)
-          )))))
-
-(defun geiser-view-last-image ()
-  "Open the last displayed image in the system's image viewer"
-  (interactive)
-  (when geiser-repl--last-image
-    (setq geiser-repl--last-image-filename
-          (make-temp-file "geiser-image" nil ".png"))
-    (let ((imgdata geiser-repl--last-image))
-      (with-temp-file geiser-repl--last-image-filename
-          (set-buffer-multibyte nil)
-          (insert imgdata))
-      (let* ((proc (start-process "Geiser image view"
-                                 nil
-                                 geiser-system-image-viewer
-                                 geiser-repl--last-image-filename)))
-        (set-process-sentinel proc
-                              '(lambda (proc evt)
-                                 (message "Deleting file %s" geiser-repl--last-image-filename)
-                                 (delete-file geiser-repl--last-image-filename)))))))
+          (setq geiser-image-cache-dir (file-name-directory file))
+          (geiser-repl--clean-image-cache))))))
+
+(defun geiser-view-last-image (n)
+  "Open the last displayed image in the system's image viewer.
+
+With prefix arg, open the N-th last shown image in the system's image viewer."
+  (interactive "p")
+  (let ((images (reverse (geiser-repl--list-image-cache))))
+    (if (>= (length images) n)
+        (start-process "Geiser image view"
+                       nil
+                       geiser-system-image-viewer
+                       (nth (- n 1) images))
+      (error "There aren't %d recent images" n))))
 
 (defun geiser-repl--output-filter (txt)
   (geiser-con--connection-update-debugging geiser-repl--connection txt)