[gimp] app: add GimpPaintTool::paint_prepare() vfunc

[Ell <ell src gnome org>]

commit ffd6c2eda24d6d6d658b15e32919f7d11be6ead9
Author: Ell <ell_se yahoo com>
Date:   Wed Oct 2 16:49:51 2019 +0300

    app: add GimpPaintTool::paint_prepare() vfunc
    
    ... which is called when starting to paint, before the tool's
    paint-core is started, allowing the tool to configure the core.
    Move the call to gimp_paint_core_set_show_all() to the default
    implementation of paint_prepare().

 app/tools/gimppainttool-paint.c |  4 +++-
 app/tools/gimppainttool.c       | 15 +++++++++++++++
 app/tools/gimppainttool.h       |  2 ++
 3 files changed, 20 insertions(+), 1 deletion(-)
---
diff --git a/app/tools/gimppainttool-paint.c b/app/tools/gimppainttool-paint.c
index cecaacd0a0..905f80360b 100644
--- a/app/tools/gimppainttool-paint.c
+++ b/app/tools/gimppainttool-paint.c
@@ -262,7 +262,9 @@ gimp_paint_tool_paint_start (GimpPaintTool     *paint_tool,
   if (gimp_paint_tool_paint_use_thread (paint_tool))
     gimp_drawable_start_paint (drawable);
 
-  gimp_paint_core_set_show_all (core, shell->show_all);
+  /*  Prepare to start the paint core  */
+  if (GIMP_PAINT_TOOL_GET_CLASS (paint_tool)->paint_prepare)
+    GIMP_PAINT_TOOL_GET_CLASS (paint_tool)->paint_prepare (paint_tool, display);
 
   /*  Start the paint core  */
   if (! gimp_paint_core_start (core,
diff --git a/app/tools/gimppainttool.c b/app/tools/gimppainttool.c
index f3d6922a33..ad8e1765a6 100644
--- a/app/tools/gimppainttool.c
+++ b/app/tools/gimppainttool.c
@@ -99,6 +99,10 @@ static void   gimp_paint_tool_oper_update    (GimpTool              *tool,
 
 static void   gimp_paint_tool_draw           (GimpDrawTool          *draw_tool);
 
+static void
+          gimp_paint_tool_real_paint_prepare (GimpPaintTool         *paint_tool,
+                                              GimpDisplay           *display);
+
 static GimpCanvasItem *
               gimp_paint_tool_get_outline    (GimpPaintTool         *paint_tool,
                                               GimpDisplay           *display,
@@ -142,6 +146,8 @@ gimp_paint_tool_class_init (GimpPaintToolClass *klass)
   tool_class->oper_update    = gimp_paint_tool_oper_update;
 
   draw_tool_class->draw      = gimp_paint_tool_draw;
+
+  klass->paint_prepare       = gimp_paint_tool_real_paint_prepare;
 }
 
 static void
@@ -817,6 +823,15 @@ gimp_paint_tool_draw (GimpDrawTool *draw_tool)
   GIMP_DRAW_TOOL_CLASS (parent_class)->draw (draw_tool);
 }
 
+static void
+gimp_paint_tool_real_paint_prepare (GimpPaintTool *paint_tool,
+                                    GimpDisplay   *display)
+{
+  GimpDisplayShell *shell = gimp_display_get_shell (display);
+
+  gimp_paint_core_set_show_all (paint_tool->core, shell->show_all);
+}
+
 static GimpCanvasItem *
 gimp_paint_tool_get_outline (GimpPaintTool *paint_tool,
                              GimpDisplay   *display,
diff --git a/app/tools/gimppainttool.h b/app/tools/gimppainttool.h
index dc383cc9b5..18e48f72ce 100644
--- a/app/tools/gimppainttool.h
+++ b/app/tools/gimppainttool.h
@@ -69,6 +69,8 @@ struct _GimpPaintToolClass
 {
   GimpColorToolClass  parent_class;
 
+  void             (* paint_prepare) (GimpPaintTool *paint_tool,
+                                      GimpDisplay   *display);
   void             (* paint_start)   (GimpPaintTool *paint_tool);
   void             (* paint_end)     (GimpPaintTool *paint_tool);
   void             (* paint_flush)   (GimpPaintTool *paint_tool);