Statusbar: add extra required widgets (NFC)

Added (to Glade, and with supporting code for the MyPaint runtime):

* Color picker button (icon taken from the Inkscape distro; GPL2+)
* Previous/next preview indicator (which might evolve a bit)
* Add missing Glade icon for the drawing window.

glade/mypaint_widgets.xml

@@ -257,8 +257,38 @@
             optional-default="True"/>
       </properties>
     </glade-widget-class>
+
+    <!-- gui/colorpicker.py -->
+    <glade-widget-class name="MyPaintBrushColorPickerButton"
+        title="Brush Color Picker Button" parent="GtkSpinner"
+        generic-name="brushcolorpickerbutton">
+      <properties>
+        <!-- Hide GtkSpinner properties -->
+        <property id="active" visible="False" save="False" />
+        <!-- Representative size for preview -->
+        <property id="width-request" default="24" optional="True"
+            optional-default="True" save="False"/>
+        <property id="height-request" default="24" optional="True"
+            optional-default="True" save="False"/>
+      </properties>
+    </glade-widget-class>
+
+    <!-- gui/colorpreview.py -->
+    <glade-widget-class name="MyPaintBrushColorIndicator"
+        title="Brush Color Indicator" parent="GtkDrawingArea"
+        generic-name="brushcolorindicator">
+      <properties>
+        <!-- Representative size for preview -->
+        <property id="width-request" default="64" optional="True"
+            optional-default="True" />
+        <property id="height-request" default="24" optional="True"
+            optional-default="True" />
+      </properties>
+    </glade-widget-class>
+
   </glade-widget-classes>
 
+
   <glade-widget-group name="MyPaint" title="MyPaint Widgets">
     <glade-widget-class-ref name="MyPaintDrawWindow"/>
     <glade-widget-class-ref name="MyPaintWorkspace"/>
@@ -269,6 +299,8 @@
     <glade-widget-class-ref name="ItemSpinBox"/>
     <glade-widget-class-ref name="DropdownPanelButton"/>
     <glade-widget-class-ref name="ButtonMappingEditor"/>
+    <glade-widget-class-ref name="MyPaintBrushColorPickerButton"/>
+    <glade-widget-class-ref name="MyPaintBrushColorIndicator"/>
   </glade-widget-group>
 
 </glade-catalog>

gui/colorpicker.py

@@ -232,3 +232,24 @@ def paint(self, cr):
 
         self._previous_area = area
 
+
+## More conventional color-picking button, with grab
+
+
+class BrushColorPickerButton (colors.ColorPickerButton):
+    """Color picker button that sets the app's working brush color."""
+
+    __gtype_name__ = "MyPaintBrushColorPickerButton"
+
+    def __init__(self):
+        colors.ColorPickerButton.__init__(self)
+        self.connect("realize", self._init_color_manager)
+
+    def _init_color_manager(self, widget):
+        from application import get_app
+        app = get_app()
+        mgr = app.brush_color_manager
+        assert mgr is not None
+        self.set_color_manager(mgr)
+
+

gui/colorpreview.py

@@ -0,0 +1,34 @@
+# This file is part of MyPaint.
+# Copyright (C) 2013 by Andrew Chadwick <a.t.chadwick@gmail.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+
+
+"""Color preview widget / current color indicator, for the status bar."""
+
+# TODO: This *might* evolve to a color preview + alpha selector, possibly
+# TODO:   with a history row taking up the bottom. For now let's draw it at
+# TODO:   an aspect ratio of about 1:5 and see how users like it.
+
+
+from colors import PreviousCurrentColorAdjuster
+
+
+class BrushColorIndicator (PreviousCurrentColorAdjuster):
+    """Previous/Current color adjuster bound to app.brush_color_manager"""
+
+    __gtype_name__ = "MyPaintBrushColorIndicator"
+
+    def __init__(self):
+        PreviousCurrentColorAdjuster.__init__(self)
+        self.connect("realize", self._init_color_manager)
+
+    def _init_color_manager(self, widget):
+        from application import get_app
+        app = get_app()
+        mgr = app.brush_color_manager
+        assert mgr is not None
+        self.set_color_manager(mgr)
+