/*! \page properties Properties
*
+@section what-is-a-property What is a property?
+
+A property is a value used by an object that can be modified or read externally to that object.
+This could be from within Dali or externally by an application.
+
+<h2 class="pg">What is a property used for?</h2>
+
+Properties can be set externally by an application, allowing that application to change the configuration or behaviour of an actor.
+This could include the physical geometry of the actor, or how it is drawn or moves.
+
+Properties can also be read. This feature can be used in conjunction with constraints to allow changes to a property within one actor to cause changes to the property of another actor. For example, an actor following the movement of another separate actor (that it is not a child of).
+
+Properties can be used to expose any useful information or behaviour of an actor.
+Other actor variables that are used to implement this bevahiour, or do not make useful sense from an application developers point of view should not be exposed.
+
+<h2 class="pg">How to implement a property within Dali-core:</h2>
+
+<b>There are two stages:</b>
+
+- Define the properties as an enum in the public-api header file.
+- Define the property details using the pre-defined macros to build up a table of property information.
+
+There are some pre-defined macros designed to help with and standardise the definition of the propery details table per class.
+
+These macros generate an array of property details which allow efficient lookup of flags like "animatable" or "constraint input".
+
+<b>Example: ImageActor</b>
+
+Within the public-api header file; image-actor.h:
+
+@code
+/**
+ * @brief An enumeration of properties belonging to the ImageActor class.
+ * Properties additional to RenderableActor.
+ */
+struct Property
+{
+ enum
+ {
+ PIXEL_AREA = DEFAULT_DERIVED_ACTOR_PROPERTY_START_INDEX, ///< name "pixel-area", type Rect<int>
+ STYLE, ///< name "style", type std::string
+ BORDER, ///< name "border", type Vector4
+ IMAGE, ///< name "image", type Map {"filename":"", "load-policy":...}
+ };
+};
+@endcode
+From @ref Dali::ImageActor::Property
+
+<b>Notes:</b>
+
+- The properties are enumerated within a named struct to give them a namespace.
+- The properties are then refered to as <OBJECT>::%Property::<PROPERTY_NAME>.
+
+Within the internal implementation; <b>image-actor-impl.cpp</b>:
+
+@code
+namespace // Unnamed namespace
+{
+
+// Properties
+
+// Name Type writable animatable constraint-input enum for index-checking
+DALI_PROPERTY_TABLE_BEGIN
+DALI_PROPERTY( "pixel-area", RECTANGLE, true, false, true, Dali::ImageActor::Property::PIXEL_AREA )
+DALI_PROPERTY( "style", STRING, true, false, true, Dali::ImageActor::Property::STYLE )
+DALI_PROPERTY( "border", VECTOR4, true, false, true, Dali::ImageActor::Property::BORDER )
+DALI_PROPERTY( "image", MAP, true, false, false, Dali::ImageActor::Property::IMAGE )
+DALI_PROPERTY_TABLE_END( DEFAULT_DERIVED_ACTOR_PROPERTY_START_INDEX )
+@endcode
+
+<b>Notes:</b>
+
+- The table lays within an unnamed namespace.
+- The table should be in the same order as the enum.
+- The table should be the only place where the text names of the properties are defined.
+- The information in the table should be used within the classes IsDefaultPropertyWritable / Animatable / ConstraintInput methods for quick lookup.
+- The last entry in the table is optionally used in debug builds for index checking.
+- The parameter to DALI_PROPERTY_TABLE_END should match the start index of the property enumeration.
+
+<br>
+<h2 class="pg">How to implement a property within Dali-toolkit:</h2>
+
+Note that toolkit properties have extra limitations in that they cannot be animated or used as a constraint input. For this reason there is no requirement for a table of property details.
+Macros are still used to define properties, but for the following reasons:
+
+To standardise the way properties are defined.
+To handle type-registering for properties, signals and actions in one place.
+To facilitate the posibility of running the code with the type-registry disabled.
+
+<b>There are two stages:</b>
+
+- Define the properties as an enum in the public-api header file, along with a definition of the property ranges.
+- Define the property details using the pre-defined macros to perform the type-registering of the properties. This is done for signals and actions also.
+
+<b>Example: Button</b>
+
+Source file: <b>button.h</b>:
+Note that the “PropertyRange” contents “PROPERTY_START_INDEX” is also used by the macro for order checking.
+
+@code
+ /**
+ * @brief The start and end property ranges for this control.
+ */
+ enum PropertyRange
+ {
+ PROPERTY_START_INDEX = Control::CONTROL_PROPERTY_END_INDEX + 1,
+ PROPERTY_END_INDEX = PROPERTY_START_INDEX + 1000 ///< Reserve property indices
+ };
+
+ /**
+ * @brief An enumeration of properties belonging to the Button class.
+ */
+ struct Property
+ {
+ enum
+ {
+ DISABLED = PROPERTY_START_INDEX, ///< name "disabled", @see SetDisabled(), type bool
+ AUTO_REPEATING, ///< name "auto-repeating", @see SetAutoRepeating(), type bool
+ INITIAL_AUTO_REPEATING_DELAY, ///< name "initial-auto-repeating-delay", @see SetInitialAutoRepeatingDelay(), type float
+ NEXT_AUTO_REPEATING_DELAY, ///< name "next-auto-repeating-delay", @see SetNextAutoRepeatingDelay(), type float
+ TOGGLABLE, ///< name "togglable", @see SetTogglableButton(), type bool
+ SELECTED, ///< name "selected", @see SetSelected(), type bool
+ NORMAL_STATE_ACTOR, ///< name "normal-state-actor", @see SetButtonImage(), type Map
+ SELECTED_STATE_ACTOR, ///< name "selected-state-actor", @see SetSelectedImage(), type Map
+ DISABLED_STATE_ACTOR, ///< name "disabled-state-actor", @see SetDisabledImage(), type Map
+ LABEL_ACTOR, ///< name "label-actor", @see SetLabel(), type Map
+ };
+ };
+@endcode
+
+Source file: <b>button-impl.cpp</b>, within an unnamed namespace:
+
+@clip{"button-impl.cpp",DALI_TYPE_REGISTRATION_BEGIN,DALI_TYPE_REGISTRATION_END}
+
+<b>Notes:</b>
+
+- The “Create” parameter to the begin macro is the function pointer to the creation function.
+- Properties should be in the same order as in the enum.
+- Signals and actions are registered likewise in that order.
+- Properties type-registered using these macros will have their order checked at compile time. If you get an indexing compile error, check the order matches the enum order.
+
+
+<br>
+<hr>
@section property-indices Property Indices
+The properties are enumerated to give them a unique index. This index can be used to access them.
+The indecies must be unique per flattened derivation heirachy.
+EG:
+- CameraActor derives from Actor. No property indicies in either CameraActor or Actor should collide with each other.
+- ActiveConstraintBase derives from Object. It CAN have property indices that match Actor or CameraActor.
+
+There are some predefined start indecies and ranges that should be used for common cases, these are defined below:
+
+
DALi has a property system and provides several different kinds of properties. The following table
shows the index range of the different properties in place.
<table>
- <tr> <td><b>Kind</b></td> <td><b>Description</b></td> <td style="text-align:center;"><b>Range</b></td> </tr>
- <tr> <td>Default</td> <td>Properties defined within DALi Core, e.g. Dali::Actor, Dali::ShaderEffect default properties etc.</td> <td style="text-align:center;">0 to 9999999</td> </tr>
- <tr> <td>Registered</td> <td>Properties registered using Dali::PropertyRegistration</td> <td style="text-align:center;">10000000 to 19999999</td> </tr>
- <tr> <td>Control</td> <td>Property range reserved by Dali::Toolkit::Control</td> <td style="text-align:center;">10000000 to 10001000<br>
- \link Dali::Toolkit::Control::CONTROL_PROPERTY_START_INDEX CONTROL_PROPERTY_START_INDEX\endlink
- to \link Dali::Toolkit::Control::CONTROL_PROPERTY_END_INDEX CONTROL_PROPERTY_END_INDEX\endlink</td> </tr>
- <tr> <td>Derived Control</td> <td>Property range for control deriving directly from Dali::Toolkit::Control</td> <td style="text-align:center;">10001001 to 19999999</td> </tr>
- <tr> <td>Custom</td> <td>Custom properties added to instance using Dali::Handle::RegisterProperty</td> <td style="text-align:center;">50000000 onwards</td> </tr>
+ <tr> <td><b>Kind</b></td> <td><b>Description</b></td> <td style="text-align:center;"><b>Start Index</b></td><td><b>End Index</b></td> </tr>
+ <tr> <td>Default</td> <td>Properties defined within DALi Core, e.g. Dali::Actor, Dali::ShaderEffect default properties etc.</td> <td style="text-align:center;">\link Dali::DEFAULT_OBJECT_PROPERTY_START_INDEX DEFAULT_OBJECT_PROPERTY_START_INDEX\endlink (0)</td><td>9999999</td> </tr>
+ <tr> <td>Registered</td> <td>Properties registered using Dali::PropertyRegistration</td> <td style="text-align:center;">\link Dali::PROPERTY_REGISTRATION_START_INDEX PROPERTY_REGISTRATION_START_INDEX\endlink (10000000)</td><td>\link Dali::PROPERTY_REGISTRATION_MAX_INDEX PROPERTY_REGISTRATION_MAX_INDEX\endlink (19999999)</td> </tr>
+ <tr> <td>Control</td> <td>Property range reserved by Dali::Toolkit::Control</td> <td style="text-align:center;">\link Dali::Toolkit::Control::CONTROL_PROPERTY_START_INDEX CONTROL_PROPERTY_START_INDEX\endlink (10000000)</td><td>
+ \link Dali::Toolkit::Control::CONTROL_PROPERTY_END_INDEX CONTROL_PROPERTY_END_INDEX\endlink (10001000)</td></tr>
+ <tr> <td>Derived Control</td> <td>Property range for control deriving directly from Dali::Toolkit::Control</td> <td style="text-align:center;">10001001</td><td>\link Dali::PROPERTY_REGISTRATION_MAX_INDEX PROPERTY_REGISTRATION_MAX_INDEX\endlink (19999999)</td> </tr>
+ <tr> <td>Custom</td> <td>Custom properties added to instance using Dali::Handle::RegisterProperty</td> <td style="text-align:center;">\link Dali::PROPERTY_CUSTOM_START_INDEX PROPERTY_CUSTOM_START_INDEX\endlink (50000000)</td><td>Onwards...</td> </tr>
</table>
+
+<br>
+<hr>
+@section property-use-example-cpp Property use example C++
+
+Common uses for properties are constraints and animations.
+
+An application developer can use an existing property, or, if necessary, register their own.
+
+Here is a code example.
+
+This example shows how to register and look-up custom properties.
+A grid of buttons is created, each with a new "tag" property which is set to a unique value. The index to this property is cached for later use.
+When pressed, the property is looked up by index (as this is much faster than a text lookup of the property name).
+
+Property lookup via index should always be used unless the indecies cannot be known. If the property reader was completely decoupled from the creation, EG. A custom control with a custom property being used by external application code, then it may be necessary. In this case the application writer should aim to perform the text lookup once at start-up, and cache the property index locally.
+
+@clip{"property-example.cpp", void Create, return true;}
+
+Once run, a grid of buttons will appear. When a button is pressed, the unique number stored in the property (in this case the index) is displayed at the bottom of the screen.
+
+<br>
+<hr>
+@section property-use-example-js Property use in JavaScript
+
+Note that constraints cannot be used within JavaScript, so below is a simple example that sets one of the default properties; scale:
+
+@code
+var image = new dali.ResourceImage( {url:"background.png"} );
+var imageActor = new dali.ImageActor( image );
+
+// by default an actor is anchored to the top-left of it's parent actor
+// change it to the middle
+imageActor.parentOrigin = dali.CENTER;
+
+// scale it up by 2 times in x,y
+imageActor.scale = [ 2, 2, 1 ];
+
+// add to the stage
+dali.stage.add( imageActor );
+@endcode
+
+For a more detailed example see the ShaderEffect example in the JavaScript documentation.
+
+<br>
+<hr>
+@section property-use-example-json Property use in JSON
+
+This is a basic example of a button defined in JSON by setting the default properties.
+
+@code
+{
+ "constants": {
+ "CONFIG_SCRIPT_LOG_LEVEL": "Verbose"
+ },
+ "stage": [
+ // First Button
+ {
+ "type": "PushButton",
+ "parent-origin": "TOP_CENTER",
+ "anchor-point": "TOP_CENTER",
+ "position": [0, 0, 0],
+ "size": [0, 200, 0],
+ "normal-state-actor": {
+ "type": "ImageActor",
+ "image": {
+ "filename": "{DALI_IMAGE_DIR}blocks-brick-1.png"
+ }
+ },
+ "selected-state-actor": {
+ "type": "ImageActor",
+ "image": {
+ "filename": "{DALI_IMAGE_DIR}blocks-brick-2.png"
+ }
+ },
+ "label-actor": {
+ "type": "TextView",
+ "text": "Normal"
+ }
+ }
+ ]
+}
+@endcode
+
*
*/
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