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>
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 typedef Rect<int32_t> ClippingBox;
51 * @brief Layers provide a mechanism for overlaying groups of actors on top of each other.
53 * When added to the stage, a layer can be ordered relative to other
54 * layers. The bottom layer is at depth zero. The stage provides a default
55 * layer for it's children (see Stage::GetRootLayer()).
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
90 * @brief Enumeration for the instance of properties belonging to the Layer class.
92 * Properties additional to Actor.
98 * @brief Enumeration for the instance of properties belonging to the Layer class.
100 * Properties additional to Actor.
105 CLIPPING_ENABLE = DEFAULT_DERIVED_ACTOR_PROPERTY_START_INDEX, ///< name "clippingEnable", type bool @SINCE_1_0.0
106 CLIPPING_BOX, ///< name "clippingBox", type Rect<int32_t> @SINCE_1_0.0
107 BEHAVIOR, ///< name "behavior", type integer or string @SINCE_1_0.0
110 * @brief The current depth of the layer.
111 * @details Name "depth", type Property::INTEGER. Read-only
112 * @note 0 is the bottom most layer, higher number is on top.
113 * @note Layer should be on the stage. If layer is not added to the stage, the depth is 0.
119 * @brief Whether to enable the depth test.
120 * @details Name "depthTest", type Property::BOOLEAN.
121 * @note By default a layer enables depth test if there is more than one opaque actor
122 * or if there is one opaque actor and one, or more, transparent actors in LAYER_3D mode.
123 * However, it's possible to disable the depth test by setting this property to False.
129 * @brief Whether this layer should consume touch (including gestures).
130 * @details Name "consumesTouch", type Property::BOOLEAN.
131 * @note When this is True, any layers behind this layer will not be hit-test.
137 * @brief Whether this layer should consume hover (including gestures).
138 * @details Name "consumesHover", type Property::BOOLEAN.
139 * @note When this is True, any layers behind this layer will not be hit-test.
147 * @brief Enumeration for the behavior of the layer.
149 * Check each value to see how it affects the layer.
155 * @brief UI control rendering mode (default mode).
157 * This mode is designed for UI controls that can overlap. In this
158 * mode renderer order will be respective to the tree hierarchy of
161 * The rendering order is depth first, so for the following actor tree,
162 * A will be drawn first, then B, D, E, then C, F. This ensures that
163 * overlapping actors are drawn as expected (whereas, with breadth first
164 * traversal, the actors would interleave).
178 * To change the order of sibling actors, use the Actor::Raise and
179 * Actor::Lower APIs. Within an actor, the Renderer depth index dictates
180 * the order the renderers are drawn.
187 * @brief Layer will use depth test.
189 * This mode is designed for a 3 dimensional scene where actors in front
190 * of other actors will obscure them, i.e. the actors are sorted by the
191 * distance from the camera.
193 * When using this mode, a depth test will be used. A depth clear will
194 * happen for each layer, which means actors in a layer "above" other
195 * layers will be rendered in front of actors in those layers regardless
196 * of their Z positions (see Layer::Raise() and Layer::Lower()).
198 * Opaque renderers are drawn first and write to the depth buffer. Then
199 * transparent renderers are drawn with depth test enabled but depth
200 * write switched off. Transparent renderers are drawn based on their
201 * distance from the camera. A renderer's DEPTH_INDEX property is used to
202 * offset the distance to the camera when ordering transparent renderers.
204 * This is useful if you want to define the draw order of two or more
205 * transparent renderers that are equal distance from the camera. Unlike
206 * LAYER_UI, parent-child relationship does not affect rendering order at
216 * @brief The sort function type.
219 * @param[in] position This is the actor translation from camera
221 typedef float (*SortFunctionType)( const Vector3& position );
224 * @brief Creates an empty Layer handle.
226 * This can be initialized with Layer::New(...).
232 * @brief Creates a Layer object.
235 * @return A handle to a newly allocated Layer
240 * @brief Downcasts a handle to Layer handle.
242 * If handle points to a Layer, the downcast produces valid handle.
243 * If not, the returned handle is left uninitialized.
245 * @param[in] handle Handle to an object
246 * @return Handle to a Layer or an uninitialized handle
248 static Layer DownCast( BaseHandle handle );
253 * This is non-virtual since derived Handle types must not contain data or virtual methods.
259 * @brief Copy constructor.
262 * @param[in] copy The actor to copy
264 Layer(const Layer& copy);
267 * @brief Assignment operator.
270 * @param[in] rhs The actor to copy
271 * @return A reference to this
273 Layer& operator=(const Layer& rhs);
276 * @brief Move constructor.
279 * @param[in] rhs The layer to move
281 Layer( Layer&& rhs );
284 * @brief Move assignment operator.
287 * @param[in] rhs The layer to move
288 * @return A reference to this
290 Layer& operator=( Layer&& rhs );
293 * @brief Increments the depth of the layer.
296 * @pre Layer is on the stage.
301 * @brief Decrements the depth of the layer.
304 * @pre Layer is on the stage.
309 * @brief Ensures the layers depth is greater than the target layer.
311 * If the layer already is above the target layer, its depth is not changed.
312 * If the layer was below target, its new depth will be immediately above target.
314 * @param target Layer to get above of
315 * @pre Layer is on the stage.
316 * @pre Target layer is on the stage.
317 * @note All layers between this layer and target get new depth values.
319 void RaiseAbove( Layer target );
322 * @brief Ensures the layers depth is less than the target layer.
324 * If the layer already is below the target layer, its depth is not changed.
325 * If the layer was above target, its new depth will be immediately below target.
327 * @param target Layer to get below of
328 * @pre Layer is on the stage.
329 * @pre Target layer is on the stage.
330 * @note All layers between this layer and target get new depth values.
332 void LowerBelow( Layer target );
335 * @brief Raises the layer to the top.
337 * @pre Layer is on the stage.
342 * @brief Lowers the layer to the bottom.
344 * @pre layer is on the stage.
346 void LowerToBottom();
349 * @brief Moves the layer directly above the given layer.
351 * After the call, this layers depth will be immediately above target.
353 * @param target Layer to get on top of
354 * @pre Layer is on the stage.
355 * @pre Target layer is on the stage.
356 * @note All layers between this layer and target get new depth values.
358 void MoveAbove( Layer target );
361 * @brief Moves the layer directly below the given layer.
363 * After the call, this layers depth will be immediately below target.
365 * @param target Layer to get below of
366 * @pre Layer is on the stage.
367 * @pre Target layer is on the stage.
368 * @note All layers between this layer and target get new depth values.
370 void MoveBelow( Layer target );
375 * @brief This allows the user to specify the sort function that the layer should use.
377 * The sort function is used to determine the order in which the actors are drawn
378 * and input is processed on the actors in the layer.
380 * A function of the following type should be used:
382 * float YourSortFunction(const Vector3& position);
386 * @param[in] function The sort function pointer
387 * @note If the sort function returns a low number, the actor with the data will be
388 * drawn in front of an actor whose data yields a high value from the sort function.
390 * @note All child layers use the same sort function. If a child layer is added to this
391 * layer, then the sort function used by the child layer will also be the same.
394 void SetSortFunction( SortFunctionType function );
397 * @brief Retrieves whether the layer consumes hover.
400 * @return @c True if consuming hover, @c false otherwise
402 bool IsHoverConsumed() const;
404 public: // Not intended for application developers
408 * @brief This constructor is used by Layer::New() methods.
411 * @param[in] Layer A pointer to a newly allocated Dali resource
413 explicit DALI_INTERNAL Layer(Internal::Layer* Layer);
422 #endif // DALI_LAYER_H