[gimp/gimp-2-10] plug-ins: backport spyrogimp Issue #5043 - reduce undos

[Jehan <jehanp src gnome org>]

commit 8caa5e93de3557834514a58cb86c815776289645
Author: Elad Shahar <dawn ever gmail com>
Date:   Tue Sep 1 03:42:34 2020 +0300

    plug-ins: backport spyrogimp Issue #5043 - reduce undos
    
    Reduce number of undo steps created by Spryrogimp previews.
    The implementation adds a function for clearing the
    incremental preview drawing that is being executed as an idle task,
    and closing an undo group in case the preview left it open (which
    would usually be the case).

 plug-ins/pygimp/plug-ins/spyro_plus.py | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)
---
diff --git a/plug-ins/pygimp/plug-ins/spyro_plus.py b/plug-ins/pygimp/plug-ins/spyro_plus.py
index 84e5218cc6..13ab48479b 100644
--- a/plug-ins/pygimp/plug-ins/spyro_plus.py
+++ b/plug-ins/pygimp/plug-ins/spyro_plus.py
@@ -1373,6 +1373,8 @@ class SpyroWindow(gtk.Window):
             adj = gtk.Adjustment(val, -180.0, 180.0, 1.0)
             myscale = hscale_in_table(adj, table, row, callback, digits=1)
             myscale.scale.add_mark(0.0, gtk.POS_BOTTOM, None)
+            myscale.spin.set_max_length(6)
+            myscale.spin.set_width_chars(6)
             return adj, myscale
 
         def set_combo_in_table(txt_list, table, row, callback):
@@ -1755,6 +1757,13 @@ class SpyroWindow(gtk.Window):
 
     # Callbacks for closing the plugin
 
+    def clear_idle_task(self):
+        if self.idle_task:
+            gobject.source_remove(self.idle_task)
+            # Close the undo group in the likely case the idle task left it open.
+            self.img.undo_group_end()
+            self.idle_task = None
+
     def ok_window(self, widget):
         """ Called when clicking on the 'close' button. """
 
@@ -1782,8 +1791,7 @@ class SpyroWindow(gtk.Window):
                 gtk.main_quit()
         else:
             # If there is an incremental drawing taking place, lets stop it.
-            if self.idle_task:
-                gobject.source_remove(self.idle_task)
+            self.clear_idle_task()
 
             if self.spyro_layer in self.img.layers:
                 self.img.remove_layer(self.spyro_layer)
@@ -1801,7 +1809,7 @@ class SpyroWindow(gtk.Window):
 
                 while self.engine.has_more_strokes():
                     yield True
-                    self.draw_next_chunk(undo_group=False, tool=tool)
+                    self.draw_next_chunk(tool=tool)
 
                 self.img.undo_group_end()
 
@@ -1815,8 +1823,7 @@ class SpyroWindow(gtk.Window):
             gobject.idle_add(task.next)
 
     def cancel_window(self, widget, what=None):
-
-        # Note that once we call gtk.main_quit, the idle task is stopped automatically.
+        self.clear_idle_task()
 
         # We want to delete the temporary layer, but as a precaution, lets ask first,
         # maybe it was already deleted by the user.
@@ -2055,16 +2062,12 @@ class SpyroWindow(gtk.Window):
 
     # Incremental drawing.
 
-    def draw_next_chunk(self, undo_group=True, tool=None):
+    def draw_next_chunk(self, tool=None):
         """ Incremental drawing """
 
         t = time.time()
 
-        if undo_group:
-            self.img.undo_group_start()
         chunk_size = self.engine.draw_next_chunk(self.drawing_layer, tool=tool)
-        if undo_group:
-            self.img.undo_group_end()
 
         draw_time = time.time() - t
         self.engine.report_time(draw_time)
@@ -2088,18 +2091,18 @@ class SpyroWindow(gtk.Window):
             self.progress_start()
             yield True
             self.engine.reset_incremental()
+
+            self.img.undo_group_start()
             while self.engine.has_more_strokes():
                 yield True
                 self.draw_next_chunk()
+            self.img.undo_group_end()
 
             self.idle_task = None
             yield False
 
-        # Remove old idle task if exists.
-        if self.idle_task:
-            gobject.source_remove(self.idle_task)
-
         # Start new idle task to perform incremental drawing in the background.
+        self.clear_idle_task()
         task = incremental_drawing()
         self.idle_task = gobject.idle_add(task.next)