5 * Copyright (c) 2020 Samsung Electronics Co., Ltd.
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
22 #include <cstdint> // uint32_t
25 #include <dali/public-api/actors/actor.h>
26 #include <dali/public-api/math/rect.h>
27 #include <dali/public-api/math/vector3.h>
28 #include <dali/public-api/object/ref-object.h>
33 * @addtogroup dali_core_actors
37 namespace Internal DALI_INTERNAL
43 * @brief Rectangle describing area on screen that a layer can draw to.
46 * @see Dali::Layer::SetClippingBox()
48 using ClippingBox = Rect<int32_t>;
51 * @brief Layers provide a mechanism for overlaying groups of actors on top of each other.
53 * When added to a scene, a layer can be ordered relative to other
54 * layers. The bottom layer is at depth zero. A scene provides a default
55 * layer for its children.
57 * Layered actors inherit position etc. as normal, but are drawn in an order
58 * determined by the layers. In case of LAYER_3D, the depth buffer is cleared
59 * before each layer is rendered unless depth test is disabled or there's no
60 * need for it based on the layer's contents; actors in lower layers cannot
61 * obscure actors in higher layers.
63 * A layer has either LAYER_UI or LAYER_3D mode. LAYER_UI has better
64 * performance, the depth test is disabled, and a child actor hides its
65 * parent actor. LAYER_3D uses the depth test, thus a close actor hides a
66 * farther one. LAYER_UI is the default mode and recommended for general
67 * cases. See Layer::Behavior and SetBehavior() for more information.
69 * Layer is a type of Actor, thus can have parent or children actors. A
70 * layer influences rendering of its all descendant actors, until another
71 * layer appears in the actor tree and manages its own subtree.
73 * If depth test is disabled, there is no performance overhead from clearing
77 * | %Action Name | %Layer method called |
78 * |-----------------|----------------------|
79 * | raise | @ref Raise() |
80 * | lower | @ref Lower() |
81 * | raiseToTop | @ref RaiseToTop() |
82 * | lowerToBottom | @ref LowerToBottom() |
85 class DALI_CORE_API Layer : public Actor
89 * @brief Enumeration for the instance of properties belonging to the Layer class.
91 * Properties additional to Actor.
97 * @brief Enumeration for the instance of properties belonging to the Layer class.
99 * Properties additional to Actor.
104 CLIPPING_ENABLE = DEFAULT_DERIVED_ACTOR_PROPERTY_START_INDEX, ///< name "clippingEnable", type bool @SINCE_1_0.0
105 CLIPPING_BOX, ///< name "clippingBox", type Rect<int32_t> @SINCE_1_0.0
106 BEHAVIOR, ///< name "behavior", type integer or string @SINCE_1_0.0
109 * @brief The current depth of the layer.
110 * @details Name "depth", type Property::INTEGER. Read-only
111 * @note 0 is the bottom most layer, higher number is on top.
112 * @note Layer should be on the stage. If layer is not added to the stage, the depth is 0.
118 * @brief Whether to enable the depth test.
119 * @details Name "depthTest", type Property::BOOLEAN.
120 * @note By default a layer enables depth test if there is more than one opaque actor
121 * or if there is one opaque actor and one, or more, transparent actors in LAYER_3D mode.
122 * However, it's possible to disable the depth test by setting this property to False.
128 * @brief Whether this layer should consume touch (including gestures).
129 * @details Name "consumesTouch", type Property::BOOLEAN.
130 * @note When this is True, any layers behind this layer will not be hit-test.
136 * @brief Whether this layer should consume hover (including gestures).
137 * @details Name "consumesHover", type Property::BOOLEAN.
138 * @note When this is True, any layers behind this layer will not be hit-test.
146 * @brief Enumeration for the behavior of the layer.
148 * Check each value to see how it affects the layer.
154 * @brief UI control rendering mode (default mode).
156 * This mode is designed for UI controls that can overlap. In this
157 * mode renderer order will be respective to the tree hierarchy of
160 * The rendering order is depth first, so for the following actor tree,
161 * A will be drawn first, then B, D, E, then C, F. This ensures that
162 * overlapping actors are drawn as expected (whereas, with breadth first
163 * traversal, the actors would interleave).
177 * To change the order of sibling actors, use the Actor::Raise and
178 * Actor::Lower APIs. Within an actor, the Renderer depth index dictates
179 * the order the renderers are drawn.
186 * @brief Layer will use depth test.
188 * This mode is designed for a 3 dimensional scene where actors in front
189 * of other actors will obscure them, i.e. the actors are sorted by the
190 * distance from the camera.
192 * When using this mode, a depth test will be used. A depth clear will
193 * happen for each layer, which means actors in a layer "above" other
194 * layers will be rendered in front of actors in those layers regardless
195 * of their Z positions (see Layer::Raise() and Layer::Lower()).
197 * Opaque renderers are drawn first and write to the depth buffer. Then
198 * transparent renderers are drawn with depth test enabled but depth
199 * write switched off. Transparent renderers are drawn based on their
200 * distance from the camera. A renderer's DEPTH_INDEX property is used to
201 * offset the distance to the camera when ordering transparent renderers.
203 * This is useful if you want to define the draw order of two or more
204 * transparent renderers that are equal distance from the camera. Unlike
205 * LAYER_UI, parent-child relationship does not affect rendering order at
215 * @brief The sort function type.
218 * @param[in] position This is the actor translation from camera
220 using SortFunctionType = float (*)(const Vector3&);
223 * @brief Creates an empty Layer handle.
225 * This can be initialized with Layer::New(...).
231 * @brief Creates a Layer object.
234 * @return A handle to a newly allocated Layer
239 * @brief Downcasts a handle to Layer handle.
241 * If handle points to a Layer, the downcast produces valid handle.
242 * If not, the returned handle is left uninitialized.
244 * @param[in] handle Handle to an object
245 * @return Handle to a Layer or an uninitialized handle
247 static Layer DownCast(BaseHandle handle);
252 * This is non-virtual since derived Handle types must not contain data or virtual methods.
258 * @brief Copy constructor.
261 * @param[in] copy The actor to copy
263 Layer(const Layer& copy);
266 * @brief Assignment operator.
269 * @param[in] rhs The actor to copy
270 * @return A reference to this
272 Layer& operator=(const Layer& rhs);
275 * @brief Move constructor.
278 * @param[in] rhs The layer to move
283 * @brief Move assignment operator.
286 * @param[in] rhs The layer to move
287 * @return A reference to this
289 Layer& operator=(Layer&& rhs);
292 * @brief Increments the depth of the layer.
295 * @pre Layer is on the stage.
300 * @brief Decrements the depth of the layer.
303 * @pre Layer is on the stage.
308 * @brief Ensures the layers depth is greater than the target layer.
310 * If the layer already is above the target layer, its depth is not changed.
311 * If the layer was below target, its new depth will be immediately above target.
313 * @param target Layer to get above of
314 * @pre Layer is on the stage.
315 * @pre Target layer is on the stage.
316 * @note All layers between this layer and target get new depth values.
318 void RaiseAbove(Layer target);
321 * @brief Ensures the layers depth is less than the target layer.
323 * If the layer already is below the target layer, its depth is not changed.
324 * If the layer was above target, its new depth will be immediately below target.
326 * @param target Layer to get below of
327 * @pre Layer is on the stage.
328 * @pre Target layer is on the stage.
329 * @note All layers between this layer and target get new depth values.
331 void LowerBelow(Layer target);
334 * @brief Raises the layer to the top.
336 * @pre Layer is on the stage.
341 * @brief Lowers the layer to the bottom.
343 * @pre layer is on the stage.
345 void LowerToBottom();
348 * @brief Moves the layer directly above the given layer.
350 * After the call, this layers depth will be immediately above target.
352 * @param target Layer to get on top of
353 * @pre Layer is on the stage.
354 * @pre Target layer is on the stage.
355 * @note All layers between this layer and target get new depth values.
357 void MoveAbove(Layer target);
360 * @brief Moves the layer directly below the given layer.
362 * After the call, this layers depth will be immediately below target.
364 * @param target Layer to get below of
365 * @pre Layer is on the stage.
366 * @pre Target layer is on the stage.
367 * @note All layers between this layer and target get new depth values.
369 void MoveBelow(Layer target);
374 * @brief This allows the user to specify the sort function that the layer should use.
376 * The sort function is used to determine the order in which the actors are drawn
377 * and input is processed on the actors in the layer.
379 * A function of the following type should be used:
381 * float YourSortFunction(const Vector3& position);
385 * @param[in] function The sort function pointer
386 * @note If the sort function returns a low number, the actor with the data will be
387 * drawn in front of an actor whose data yields a high value from the sort function.
389 * @note All child layers use the same sort function. If a child layer is added to this
390 * layer, then the sort function used by the child layer will also be the same.
393 void SetSortFunction(SortFunctionType function);
396 * @brief Retrieves whether the layer consumes hover.
399 * @return @c True if consuming hover, @c false otherwise
401 bool IsHoverConsumed() const;
403 public: // Not intended for application developers
406 * @brief This constructor is used by Layer::New() methods.
409 * @param[in] Layer A pointer to a newly allocated Dali resource
411 explicit DALI_INTERNAL Layer(Internal::Layer* Layer);
420 #endif // DALI_LAYER_H