Customizing the Unity Editor - Mastering Unity Scripting - page 268

The following are the comments for code sample 8-7:
• Line 01 : The CustomPropertyDrawer attribute is used here to associate
the PropertyDrawer class with the ColorRangeAttribute attribute. The
Unity Editor uses this metadata internally to determine which types require
custom rendering in the Object Inspector. In this case, all members with
ColorRangeAttribute will be drawn manually by the OnGUI function of the
PropertyDrawer class.
• Line 11 : The OnGUI function is overridden from the base class to define how
all fields with ColorRangeAttribute should be rendered in the Object
Inspector. EditorGUI is a native Unity Editor utility class for drawing GUI
elements, such as buttons, textboxes, and sliders. For more information on
EditorGUI , see the online documentation at http://docs.unity3d.com/
ScriptReference/EditorGUI.html .
• Line 14 : The OnGUI function is called once, perhaps many times per second,
for each unique member to render manually in the Object Inspector. The
attribute data for ColorRangeAttribute is retrieved here with typecasting,
and this gives us access directly to all its members for the current object
being rendered. To access the member variables of the object itself (for read/
write access), as opposed to its attribute, the SerializedProperty argument
should be used, such as the FindPropertyRelative method. For more
information, see the online Unity documentation at http://docs.unity3d.
com/ScriptReference/SerializedProperty.html .
• Line 24 : From here onwards, the FindPropertyRelative function is called
to retrieve public member variables, such as the SourceColor , DestColor ,
and BlendedColor in the selected object. This is where the values are
actually set by moving the slider component.
More information on the PropertyDrawer class can be found in the
online Unity documentation at http://docs.unity3d.com/Manual/
editor-PropertyDrawers.html .
The code sample 8-7 overrides the Object Inspector drawing for any ColorBlend
instances when tagged with the ColorRangeAttribute attribute. This offers an
accessible and easy-to-use way of creating blended colors. Remember, you can
make your source and destination colors public, in order to be accessible from the
Inspector tab, as shown here: