[gimp] app: add prepare-to-remove-slider signal to GimpToolLine

[N/A <ell src gnome org>]

commit 50acb6690d9c3927749578b699de88758cc9b001
Author: Ell <ell_se yahoo com>
Date:   Fri Oct 6 12:04:01 2017 -0400

    app: add prepare-to-remove-slider signal to GimpToolLine
    
    The signal is emitted when a slider is dragged away from the line,
    and will be removed when the button is released, and when the
    slider is dragged back to the vicinity of the line, and won't be
    removed.  The last parameter of the signal is a boolean flag
    differentiating between the two cases.
    
    Note that a remove-slider signal may be emitted without a preceeding
    prepare-to-remove-slider signal, however, is a prepare-to-remove-
    slider signal is emitted with a TRUE last parameter, it must be
    eventually followed by a remove-slider signal, or by another
    prepare-to-remove-slider signal with a FALSE last parameter.

 app/core/gimpmarshal.list  |    1 +
 app/display/gimptoolline.c |   62 ++++++++++++++++++++++++++++++++++----------
 app/display/gimptoolline.h |   17 +++++++-----
 3 files changed, 59 insertions(+), 21 deletions(-)
---
diff --git a/app/core/gimpmarshal.list b/app/core/gimpmarshal.list
index add1892..f44c1c7 100644
--- a/app/core/gimpmarshal.list
+++ b/app/core/gimpmarshal.list
@@ -47,6 +47,7 @@ VOID: ENUM, OBJECT
 VOID: ENUM, POINTER
 VOID: FLAGS
 VOID: INT
+VOID: INT, BOOLEAN
 VOID: INT, INT
 VOID: INT, INT, INT, INT
 VOID: INT, INT, BOOLEAN, BOOLEAN
diff --git a/app/display/gimptoolline.c b/app/display/gimptoolline.c
index dfa3fba..4c6664e 100644
--- a/app/display/gimptoolline.c
+++ b/app/display/gimptoolline.c
@@ -85,6 +85,7 @@ enum
 {
   CAN_ADD_SLIDER,
   ADD_SLIDER,
+  PREPARE_TO_REMOVE_SLIDER,
   REMOVE_SLIDER,
   SELECTION_CHANGED,
   LAST_SIGNAL
@@ -242,6 +243,17 @@ gimp_tool_line_class_init (GimpToolLineClass *klass)
                   G_TYPE_INT, 1,
                   G_TYPE_DOUBLE);
 
+  line_signals[PREPARE_TO_REMOVE_SLIDER] =
+    g_signal_new ("prepare-to-remove-slider",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpToolLineClass, prepare_to_remove_slider),
+                  NULL, NULL,
+                  gimp_marshal_VOID__INT_BOOLEAN,
+                  G_TYPE_NONE, 2,
+                  G_TYPE_INT,
+                  G_TYPE_BOOLEAN);
+
   line_signals[REMOVE_SLIDER] =
     g_signal_new ("remove-slider",
                   G_TYPE_FROM_CLASS (klass),
@@ -670,6 +682,14 @@ gimp_tool_line_button_release (GimpToolWidget        *widget,
             {
               gimp_tool_line_get_slider (line, private->selection)->value =
                 private->saved_slider_value;
+
+              if (private->remove_slider)
+                {
+                  private->remove_slider = FALSE;
+
+                  g_signal_emit (line, line_signals[PREPARE_TO_REMOVE_SLIDER], 0,
+                                 private->selection, FALSE);
+                }
             }
 
           g_object_set (line,
@@ -682,6 +702,8 @@ gimp_tool_line_button_release (GimpToolWidget        *widget,
     }
   else if (grab == GRAB_SELECTION && private->remove_slider)
     {
+      private->remove_slider = FALSE;
+
       g_signal_emit (line, line_signals[REMOVE_SLIDER], 0,
                      private->selection);
     }
@@ -1124,6 +1146,7 @@ gimp_tool_line_selection_motion (GimpToolLine *line,
         GimpControllerSlider *slider;
         gdouble               value;
         gdouble               dist;
+        gboolean              remove_slider;
 
         shell = gimp_tool_widget_get_shell (GIMP_TOOL_WIDGET (line));
 
@@ -1144,25 +1167,36 @@ gimp_tool_line_selection_motion (GimpToolLine *line,
                       NULL);
 
         /* slider tearing */
-        private->remove_slider = dist > SLIDER_TEAR_DISTANCE;
+        remove_slider = dist > SLIDER_TEAR_DISTANCE;
 
-        /* eek! */
-        {
-          GimpCursorType     cursor;
-          GimpToolCursorType tool_cursor;
-          GimpCursorModifier modifier;
+        if (remove_slider != private->remove_slider)
+          {
+            private->remove_slider = remove_slider;
 
-          cursor      = shell->current_cursor;
-          tool_cursor = shell->tool_cursor;
-          modifier    = GIMP_CURSOR_MODIFIER_NONE;
+            g_signal_emit (line, line_signals[PREPARE_TO_REMOVE_SLIDER], 0,
+                           private->selection, remove_slider);
 
-          gimp_tool_line_get_cursor (GIMP_TOOL_WIDGET (line), NULL, 0,
-                                     &cursor, &tool_cursor, &modifier);
+            /* set the cursor modifier to a minus by talking to the shell
+             * directly -- eek!
+             */
+            {
+              GimpCursorType     cursor;
+              GimpToolCursorType tool_cursor;
+              GimpCursorModifier modifier;
 
-          gimp_display_shell_set_cursor (shell, cursor, tool_cursor, modifier);
-        }
+              cursor      = shell->current_cursor;
+              tool_cursor = shell->tool_cursor;
+              modifier    = GIMP_CURSOR_MODIFIER_NONE;
 
-        gimp_tool_line_update_handles (line);
+              gimp_tool_line_get_cursor (GIMP_TOOL_WIDGET (line), NULL, 0,
+                                         &cursor, &tool_cursor, &modifier);
+
+              gimp_display_shell_set_cursor (shell, cursor, tool_cursor, modifier);
+            }
+
+            gimp_tool_line_update_handles (line);
+            gimp_tool_line_update_circle (line);
+          }
 
         return TRUE;
       }
diff --git a/app/display/gimptoolline.h b/app/display/gimptoolline.h
index d9a557c..8642a35 100644
--- a/app/display/gimptoolline.h
+++ b/app/display/gimptoolline.h
@@ -60,13 +60,16 @@ struct _GimpToolLineClass
   GimpToolWidgetClass  parent_class;
 
   /*  signals  */
-  gboolean (* can_add_slider)    (GimpToolLine *line,
-                                  gdouble       value);
-  gint     (* add_slider)        (GimpToolLine *line,
-                                  gdouble       value);
-  void     (* remove_slider)     (GimpToolLine *line,
-                                  gint          slider);
-  void     (* selection_changed) (GimpToolLine *line);
+  gboolean (* can_add_slider)           (GimpToolLine *line,
+                                         gdouble       value);
+  gint     (* add_slider)               (GimpToolLine *line,
+                                         gdouble       value);
+  void     (* prepare_to_remove_slider) (GimpToolLine *line,
+                                         gint          slider,
+                                         gboolean      remove);
+  void     (* remove_slider)            (GimpToolLine *line,
+                                         gint          slider);
+  void     (* selection_changed)        (GimpToolLine *line);
 };