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/object/ref-object.h>
26 #include <dali/public-api/actors/actor.h>
27 #include <dali/public-api/math/rect.h>
28 #include <dali/public-api/math/vector3.h>
29 #include <dali/public-api/images/frame-buffer-image.h>
34 * @addtogroup dali_core_actors
38 namespace Internal DALI_INTERNAL
44 * @brief Rectangle describing area on screen that a layer can draw to.
47 * @see Dali::Layer::SetClippingBox()
49 typedef Rect<int32_t> ClippingBox;
52 * @brief Layers provide a mechanism for overlaying groups of actors on top of each other.
54 * When added to the stage, a layer can be ordered relative to other
55 * layers. The bottom layer is at depth zero. The stage provides a default
56 * layer for it's children (see Stage::GetRootLayer()).
58 * Layered actors inherit position etc. as normal, but are drawn in an order
59 * determined by the layers. In case of LAYER_3D, the depth buffer is cleared
60 * before each layer is rendered unless depth test is disabled or there's no
61 * need for it based on the layer's contents; actors in lower layers cannot
62 * obscure actors in higher layers.
64 * A layer has either LAYER_UI or LAYER_3D mode. LAYER_UI has better
65 * performance, the depth test is disabled, and a child actor hides its
66 * parent actor. LAYER_3D uses the depth test, thus a close actor hides a
67 * farther one. LAYER_UI is the default mode and recommended for general
68 * cases. See Layer::Behavior and SetBehavior() for more information.
70 * Layer is a type of Actor, thus can have parent or children actors. A
71 * layer influences rendering of its all descendant actors, until another
72 * layer appears in the actor tree and manages its own subtree.
74 * If depth test is disabled, there is no performance overhead from clearing
78 * | %Action Name | %Layer method called |
79 * |-----------------|----------------------|
80 * | raise | @ref Raise() |
81 * | lower | @ref Lower() |
82 * | raiseToTop | @ref RaiseToTop() |
83 * | lowerToBottom | @ref LowerToBottom() |
86 class DALI_CORE_API Layer : public Actor
91 * @brief Enumeration for the instance of properties belonging to the Layer class.
93 * Properties additional to Actor.
99 * @brief Enumeration for the instance of properties belonging to the Layer class.
101 * Properties additional to Actor.
106 CLIPPING_ENABLE = DEFAULT_DERIVED_ACTOR_PROPERTY_START_INDEX, ///< name "clippingEnable", type bool @SINCE_1_0.0
107 CLIPPING_BOX, ///< name "clippingBox", type Rect<int32_t> @SINCE_1_0.0
108 BEHAVIOR, ///< name "behavior", type integer or string @SINCE_1_0.0
111 * @brief The current depth of the layer.
112 * @details Name "depth", type Property::INTEGER. Read-only
113 * @note 0 is the bottom most layer, higher number is on top.
114 * @note Layer should be on the stage. If layer is not added to the stage, the depth is 0.
120 * @brief Whether to enable the depth test.
121 * @details Name "depthTest", type Property::BOOLEAN.
122 * @note By default a layer enables depth test if there is more than one opaque actor
123 * or if there is one opaque actor and one, or more, transparent actors in LAYER_3D mode.
124 * However, it's possible to disable the depth test by setting this property to False.
130 * @brief Whether this layer should consume touch (including gestures).
131 * @details Name "consumesTouch", type Property::BOOLEAN.
132 * @note When this is True, any layers behind this layer will not be hit-test.
138 * @brief Whether this layer should consume hover (including gestures).
139 * @details Name "consumesHover", type Property::BOOLEAN.
140 * @note When this is True, any layers behind this layer will not be hit-test.
148 * @brief Enumeration for the behavior of the layer.
150 * Check each value to see how it affects the layer.
156 * @brief UI control rendering mode (default mode).
158 * This mode is designed for UI controls that can overlap. In this
159 * mode renderer order will be respective to the tree hierarchy of
162 * The rendering order is depth first, so for the following actor tree,
163 * A will be drawn first, then B, D, E, then C, F. This ensures that
164 * overlapping actors are drawn as expected (whereas, with breadth first
165 * traversal, the actors would interleave).
179 * To change the order of sibling actors, use the Actor::Raise and
180 * Actor::Lower APIs. Within an actor, the Renderer depth index dictates
181 * the order the renderers are drawn.
188 * @brief Layer will use depth test.
190 * This mode is designed for a 3 dimensional scene where actors in front
191 * of other actors will obscure them, i.e. the actors are sorted by the
192 * distance from the camera.
194 * When using this mode, a depth test will be used. A depth clear will
195 * happen for each layer, which means actors in a layer "above" other
196 * layers will be rendered in front of actors in those layers regardless
197 * of their Z positions (see Layer::Raise() and Layer::Lower()).
199 * Opaque renderers are drawn first and write to the depth buffer. Then
200 * transparent renderers are drawn with depth test enabled but depth
201 * write switched off. Transparent renderers are drawn based on their
202 * distance from the camera. A renderer's DEPTH_INDEX property is used to
203 * offset the distance to the camera when ordering transparent renderers.
205 * This is useful if you want to define the draw order of two or more
206 * transparent renderers that are equal distance from the camera. Unlike
207 * LAYER_UI, parent-child relationship does not affect rendering order at
217 * @DEPRECATED_1_2.26. Not intended for application use.
219 * @brief Enumeration for TREE_DEPTH_MULTIPLIER is used by the rendering sorting algorithm to decide which actors to render first.
222 enum TreeDepthMultiplier
224 TREE_DEPTH_MULTIPLIER = 10000,
228 * @brief The sort function type.
231 * @param[in] position This is the actor translation from camera
233 typedef float (*SortFunctionType)( const Vector3& position );
236 * @brief Creates an empty Layer handle.
238 * This can be initialized with Layer::New(...).
244 * @brief Creates a Layer object.
247 * @return A handle to a newly allocated Layer
252 * @brief Downcasts a handle to Layer handle.
254 * If handle points to a Layer, the downcast produces valid handle.
255 * If not, the returned handle is left uninitialized.
257 * @param[in] handle Handle to an object
258 * @return Handle to a Layer or an uninitialized handle
260 static Layer DownCast( BaseHandle handle );
265 * This is non-virtual since derived Handle types must not contain data or virtual methods.
271 * @brief Copy constructor.
274 * @param[in] copy The actor to copy
276 Layer(const Layer& copy);
279 * @brief Assignment operator.
282 * @param[in] rhs The actor to copy
283 * @return A reference to this
285 Layer& operator=(const Layer& rhs);
288 * @brief Increments the depth of the layer.
291 * @pre Layer is on the stage.
296 * @brief Decrements the depth of the layer.
299 * @pre Layer is on the stage.
304 * @brief Ensures the layers depth is greater than the target layer.
306 * If the layer already is above the target layer, its depth is not changed.
307 * If the layer was below target, its new depth will be immediately above target.
309 * @param target Layer to get above of
310 * @pre Layer is on the stage.
311 * @pre Target layer is on the stage.
312 * @note All layers between this layer and target get new depth values.
314 void RaiseAbove( Layer target );
317 * @brief Ensures the layers depth is less than the target layer.
319 * If the layer already is below the target layer, its depth is not changed.
320 * If the layer was above target, its new depth will be immediately below target.
322 * @param target Layer to get below of
323 * @pre Layer is on the stage.
324 * @pre Target layer is on the stage.
325 * @note All layers between this layer and target get new depth values.
327 void LowerBelow( Layer target );
330 * @brief Raises the layer to the top.
332 * @pre Layer is on the stage.
337 * @brief Lowers the layer to the bottom.
339 * @pre layer is on the stage.
341 void LowerToBottom();
344 * @brief Moves the layer directly above the given layer.
346 * After the call, this layers depth will be immediately above target.
348 * @param target Layer to get on top of
349 * @pre Layer is on the stage.
350 * @pre Target layer is on the stage.
351 * @note All layers between this layer and target get new depth values.
353 void MoveAbove( Layer target );
356 * @brief Moves the layer directly below the given layer.
358 * After the call, this layers depth will be immediately below target.
360 * @param target Layer to get below of
361 * @pre Layer is on the stage.
362 * @pre Target layer is on the stage.
363 * @note All layers between this layer and target get new depth values.
365 void MoveBelow( Layer target );
370 * @brief This allows the user to specify the sort function that the layer should use.
372 * The sort function is used to determine the order in which the actors are drawn
373 * and input is processed on the actors in the layer.
375 * A function of the following type should be used:
377 * float YourSortFunction(const Vector3& position);
381 * @param[in] function The sort function pointer
382 * @note If the sort function returns a low number, the actor with the data will be
383 * drawn in front of an actor whose data yields a high value from the sort function.
385 * @note All child layers use the same sort function. If a child layer is added to this
386 * layer, then the sort function used by the child layer will also be the same.
389 void SetSortFunction( SortFunctionType function );
392 * @brief Retrieves whether the layer consumes hover.
395 * @return @c True if consuming hover, @c false otherwise
397 bool IsHoverConsumed() const;
399 public: // Not intended for application developers
403 * @brief This constructor is used by Layer::New() methods.
406 * @param[in] Layer A pointer to a newly allocated Dali resource
408 explicit DALI_INTERNAL Layer(Internal::Layer* Layer);
417 #endif // DALI_LAYER_H