From a8e0b5cd566c9923ba7ca945b17ca80f8a8e4817 Mon Sep 17 00:00:00 2001
From: wailo <wailo_2@hotmail.com>
Date: Thu, 25 Apr 2019 22:34:46 +0200
Subject: [PATCH] Improving preview functionality. No buffer switch.

- Using temp buffer instead of new buffer.
- Windows layout is retained. No need to switch buffer after every preview
---
 plantuml-mode.el | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/plantuml-mode.el b/plantuml-mode.el
index 2cf2cf6..3ecef89 100644
--- a/plantuml-mode.el
+++ b/plantuml-mode.el
@@ -262,33 +262,28 @@ to choose where to display it:
 - 4  (when prefixing the command with C-u) -> new window
 - 16 (when prefixing the command with C-u C-u) -> new frame.
 - else -> new buffer"
-  (let ((b (get-buffer plantuml-preview-buffer)))
-    (when b
-      (kill-buffer b)))
-
   (let* ((imagep (and (display-images-p)
                       (plantuml-is-image-output-p)))
          (process-connection-type nil)
-         (buf (get-buffer-create plantuml-preview-buffer))
          (coding-system-for-read (and imagep 'binary))
          (coding-system-for-write (and imagep 'binary)))
 
-    (let ((ps (plantuml-start-process buf)))
-      (process-send-string ps string)
-      (process-send-eof ps)
-      (set-process-sentinel ps
-                            (lambda (_ps event)
-                              (unless (equal event "finished\n")
-                                (error "PLANTUML Preview failed: %s" event))
-                              (cond
-                               ((= prefix 16)
-                                (switch-to-buffer-other-frame plantuml-preview-buffer))
-                               ((= prefix 4)
-                                (switch-to-buffer-other-window plantuml-preview-buffer))
-                               (t (switch-to-buffer plantuml-preview-buffer)))
-                              (when imagep
-                                (image-mode)
-                                (set-buffer-multibyte t)))))))
+    (with-output-to-temp-buffer plantuml-preview-buffer
+      (let* ((buf (get-buffer-create plantuml-preview-buffer)) (ps (plantuml-start-process buf)))
+        (process-send-string ps string)
+        (process-send-eof ps)
+        (set-process-sentinel ps
+                              (lambda (_ps event)
+                                (unless (equal event "finished\n")
+                                  (error "PLANTUML Preview failed: %s" event))
+                                (cond
+                                 ((= prefix 16)
+                                  (switch-to-buffer-other-frame plantuml-preview-buffer))
+                                 ((= prefix 4)
+                                  (switch-to-buffer-other-window plantuml-preview-buffer)))
+                                (when imagep
+                                  (image-mode)
+                                  (set-buffer-multibyte t))))))))
 
 (defun plantuml-preview-buffer (prefix)
   "Preview diagram from the PlantUML sources in the current buffer.