Fix scroll problem on buffers with free content and non-allocated lines (bug #32039)

ChangeLog

@@ -1,7 +1,7 @@
 WeeChat ChangeLog
 =================
 Sébastien Helleu <flashcode@flashtux.org>
-v0.3.4-rc3, 2011-01-04
+v0.3.4-rc3, 2011-01-05
 
 
 Version 0.3.4 (under dev!)
@@ -9,6 +9,8 @@ Version 0.3.4 (under dev!)
 
 * core: add 256 colors support, new command /color, new section "palette" in
   weechat.conf (task #6834)
+* core: fix scroll problem on buffers with free content and non-allocated lines
+  (bug #32039)
 * core: add info "weechat_upgrading", signal "upgrade_ended", display duration
   of upgrade
 * core: replace the 10 nick color options and number of nick colors by a single

src/gui/gui-chat.c

@@ -35,7 +35,6 @@
 #include "../core/weechat.h"
 #include "../core/wee-config.h"
 #include "../core/wee-hook.h"
-#include "../core/wee-log.h"
 #include "../core/wee-string.h"
 #include "../core/wee-utf8.h"
 #include "../plugins/plugin.h"
@@ -657,6 +656,7 @@ gui_chat_printf_y (struct t_gui_buffer *buffer, int y, const char *message, ...)
     va_list argptr;
     struct t_gui_line *ptr_line;
     char strbuf[8192];
+    int i, num_lines_to_add;
     
     if (gui_init_ok)
     {
@@ -689,7 +689,10 @@ gui_chat_printf_y (struct t_gui_buffer *buffer, int y, const char *message, ...)
             }
             if (ptr_line && (ptr_line->data->y == y))
             {
-                gui_line_free (buffer, ptr_line);
+                if (ptr_line->next_line)
+                    gui_line_clear (ptr_line);
+                else
+                    gui_line_free (buffer, ptr_line);
                 gui_buffer_ask_chat_refresh (buffer, 2);
             }
         }
@@ -698,6 +701,23 @@ gui_chat_printf_y (struct t_gui_buffer *buffer, int y, const char *message, ...)
     {
         if (gui_init_ok)
         {
+            num_lines_to_add = 0;
+            if (buffer->own_lines && buffer->own_lines->last_line)
+                num_lines_to_add = y - buffer->own_lines->last_line->data->y - 1;
+            else
+                num_lines_to_add = y;
+            if (num_lines_to_add > 0)
+            {
+                /*
+                 * add empty line(s) before asked line, to ensure there is at
+                 * least "y" lines in buffer, and then be able to scroll
+                 * properly buffer page by page
+                 */
+                for (i = y - num_lines_to_add; i < y; i++)
+                {
+                    gui_line_add_y (buffer, i, "");
+                }
+            }
             gui_line_add_y (buffer, y, strbuf);
             gui_buffer_ask_chat_refresh (buffer, 1);
         }

src/gui/gui-line.c

@@ -896,9 +896,6 @@ gui_line_add_y (struct t_gui_buffer *buffer, int y, const char *message)
     struct t_gui_line *ptr_line, *new_line;
     struct t_gui_line_data *new_line_data;
     
-    if (!message || !message[0])
-        return;
-    
     /* search if line exists for "y" */
     for (ptr_line = buffer->own_lines->first_line; ptr_line;
          ptr_line = ptr_line->next_line)
@@ -970,7 +967,7 @@ gui_line_add_y (struct t_gui_buffer *buffer, int y, const char *message)
     /* set message for line */
     if (ptr_line->data->message)
         free (ptr_line->data->message);
-    ptr_line->data->message = strdup (message);
+    ptr_line->data->message = (message) ? strdup (message) : strdup ("");
     
     /* check if line is filtered or not */
     ptr_line->data->displayed = gui_filter_check_line (buffer, ptr_line);
@@ -987,6 +984,23 @@ gui_line_add_y (struct t_gui_buffer *buffer, int y, const char *message)
     ptr_line->data->refresh_needed = 1;
 }
 
+/*
+ * gui_line_clear: clear prefix and message on a line
+ *                 (used on buffers with free content only)
+ */
+
+void
+gui_line_clear (struct t_gui_line *line)
+{
+    if (line->data->prefix)
+        free (line->data->prefix);
+    line->data->prefix = strdup ("");
+    
+    if (line->data->message)
+        free (line->data->message);
+    line->data->message = strdup ("");
+}
+
 /*
  * gui_line_mix_buffers: mix lines of a buffer (or group of buffers) with a new
  *                       buffer

src/gui/gui-line.h

@@ -100,6 +100,7 @@ extern struct t_gui_line *gui_line_add (struct t_gui_buffer *buffer,
                                         const char *message);
 extern void gui_line_add_y (struct t_gui_buffer *buffer, int y,
                             const char *message);
+extern void gui_line_clear (struct t_gui_line *line);
 extern void gui_line_mix_buffers (struct t_gui_buffer *buffer);
 extern int gui_line_add_to_infolist (struct t_infolist *infolist,
                                      struct t_gui_lines *lines,