+ * @brief A Visual provides a renderer for drawing a control component. A control may have multiple visuals.
+ *
+ * Visuals reuse geometry, shader etc. across controls. They ensure that the renderer and texture sets exist only when control is on-stage.
+ * Each visual also responds to actor size and color change, and provides clipping at the renderer level.
+ * Note: The visual responds to the the Actor::COLOR by blending it with the 'Multiply' operator.
+ *
+ * The following properties are optional, but can be supplied in the property map to Dali::Toolkit::VisualFactory::CreateVisual().
+ *
+ * | %Property Name | Type |
+ * |-------------------------|------------------|
+ * | customShader | MAP |
+ * | transform | MAP |
+ *
+ * where \b customShader is a map with at least one of the following properties:
+ * | %Property Name | Type | Required | Default | Description |
+ * |-------------------------|----------------------------|----------|---------|-----------------------------------------|
+ * | vertexShader | STRING | No | "" | Vertex shader code |
+ * | fragmentShader | STRING | No | "" | Fragment shader code |
+ * | subdivideGridX | INTEGER | No | 1 | How to subdivide the grid along X |
+ * | subdivideGridY | INTEGER | No | 1 | How to subdivide the grid along Y |
+ * | shaderHints | INTEGER or ARRAY of STRING | No | NONE | Bitmask of hints @sa Dali::Shader::Hint |
+ *
+ * and \b transform is a map with the following properties:
+ * | %Property Name | Type | Required | Default | Description |
+ * |-------------------------|-------------------|----------|------------------------|-----------------------------------------------------|
+ * | offset | VECTOR2 | No | (0,0) | Offset of visual from origin |
+ * | size | VECTOR2 | No | (1,1) | size of visual |
+ * | origin | INTEGER or STRING | No | CENTER | origin of the visual @sa Dali::Toolkit::Align |
+ * | anchorPoint | INTEGER or STRING | No | CENTER | anchor point of the visual @sa Dali::Toolkit::Align |
+ * | offsetPolicy | VECTOR2 | No | ( RELATIVE, RELATIVE ) | @sa Dali::Toolkit::Visual::Transform::Policy |
+ * | sizePolicy | VECTOR2 | No | ( RELATIVE, RELATIVE ) | @sa Dali::Toolkit::Visual::Transform::Policy |
+ *
+ * Relative means that the component describes a factor of the parent control size;
+ * size.x = 1 means full width; size.y = 0.5 means half height.
+ *
+ * Absolute means that the component describes world units (equivalent to pixels)