1 #ifndef __DALI_RESOURCE_IMAGE_H__
2 #define __DALI_RESOURCE_IMAGE_H__
5 * Copyright (c) 2015 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.
25 #include <dali/public-api/common/loading-state.h>
26 #include <dali/public-api/images/image.h>
27 #include <dali/public-api/signals/dali-signal.h>
32 class ImageAttributes;
34 namespace Internal DALI_INTERNAL
40 * @brief ResourceImage is an image loaded using a URL
42 * <h3>ResourceImage Loading</h3>
44 * When the ResourceImage is created, resource loading will be attempted unless
45 * the ResourceImage is created with IMMEDIATE loading policy or a compatible resource is found in cache.
46 * In case of loading images ON_DEMAND, resource loading will only be attempted if the associated ImageActor
48 * Custom loading requests can be made by providing an ImageAttributes object to ResourceImage::New().
51 * - IMMEDIATE: acquire image resource when creating ResourceImage.
52 * - ON_DEMAND: only load in case the associated ImageActor is put on Stage
54 * <i>Resolution of conflicting policies</i>
55 * If the same image is created more than once with conflicting policies, LoadPolicy "IMMEDIATE" overrides "ON_DEMAND".
57 * <i>Custom load requests</i>
58 * Size, scaling mode, orientation compensation can be set when requesting an image.
59 * See ImageAttributes for more details.
61 * <i>Compatible resources</i>
63 * Before loading a new ResourceImage the internal image resource cache is checked by dali.
64 * If there is an image already loaded in memory and is deemed "compatible" with the requested image,
65 * that resource is reused.
66 * This happens for example if a loaded image exists with the same URL, and the difference between both
67 * of the dimensions is less than 50%.
69 * <i>Reloading images</i>
71 * The same request used on creating the ResourceImage is re-issued when reloading images.
72 * If the file changed since the last load operation, this might result in a different resource.
73 * Reload only takes effect if both of these conditions apply:
74 * - The ResourceImage has already finished loading
75 * - The ResourceImage is either on Stage or using IMMEDIATE load policy
78 * | %Signal Name | Method |
79 * |------------------------|------------------------------|
80 * | image-loading-finished | @ref LoadingFinishedSignal() |
82 class DALI_IMPORT_API ResourceImage : public Image
86 * @brief Resource management options.
90 * @brief LoadPolicy controls the way images are loaded into memory.
94 IMMEDIATE, ///< load image once it is created (default)
95 ON_DEMAND ///< delay loading until the image is being used (a related actor is added to Stage)
99 * @brief Type of signal for LoadingFinished and Uploaded.
101 typedef Signal< void (ResourceImage) > ResourceImageSignal;
106 * @brief Get the size of an image from disk.
108 * This function will read the header info from file on disk and is
109 * synchronous, so it should not be used repeatedly or in tight
112 * @param [in] url The URL of the image file.
113 * @return The width and height in pixels of the image.
115 static Vector2 GetImageSize( const std::string& url );
118 * @brief Constructor which creates an empty ResourceImage object.
120 * Use ResourceImage::New(...) to create an initialised object.
127 * This is non-virtual since derived Handle types must not contain data or virtual methods.
132 * @brief This copy constructor is required for (smart) pointer semantics.
134 * @param [in] handle A reference to the copied handle
136 ResourceImage( const ResourceImage& handle );
139 * @brief This assignment operator is required for (smart) pointer semantics.
141 * @param [in] rhs A reference to the copied handle
142 * @return A reference to this
144 ResourceImage& operator=( const ResourceImage& rhs );
147 * @brief Create an initialised ResourceImage object.
149 * @param [in] url The URL of the image file to use.
150 * @return A handle to a newly allocated object
152 static ResourceImage New( const std::string& url );
155 * @brief Create an initialised ResourceImage object.
157 * @param [in] url The URL of the image file to use.
158 * @param [in] loadPol The LoadPolicy to apply when loading the image resource.
159 * @param [in] releasePol The ReleasePolicy to apply to Image.
160 * @return A handle to a newly allocated object
162 static ResourceImage New( const std::string& url, LoadPolicy loadPol, ReleasePolicy releasePol );
165 * @brief Create an initialised ResourceImage object.
167 * @param [in] url The URL of the image file to use.
168 * @param [in] attributes Requested parameters for loading (size, scaling etc.).
169 * @return A handle to a newly allocated object
171 static ResourceImage New( const std::string& url, const ImageAttributes& attributes );
174 * @brief Create an initialised ResourceImage object.
176 * @param [in] url The URL of the image file to use.
177 * @param [in] attributes Requested parameters for loading (size, scaling etc.).
178 * @param [in] loadPol The LoadPolicy to apply when loading the image resource.
179 * @param [in] releasePol The ReleasePolicy to apply to Image.
180 * @return A handle to a newly allocated object
182 static ResourceImage New( const std::string& url, const ImageAttributes& attributes, LoadPolicy loadPol, ReleasePolicy releasePol );
185 * @brief Downcast an Object handle to ResourceImage handle.
187 * If handle points to a ResourceImage object the
188 * downcast produces valid handle. If not the returned handle is left uninitialized.
189 * @param[in] handle to An object
190 * @return handle to a Image object or an uninitialized handle
192 static ResourceImage DownCast( BaseHandle handle );
195 * @brief Return load policy.
197 * @return resource load policy
199 LoadPolicy GetLoadPolicy() const;
202 * @brief Query whether the image data has loaded.
204 * The asynchronous loading begins when the Image object is created.
205 * After the Image object is discarded, the image data will be released from memory.
206 * @return The loading state, either Loading, Success or Failed.
208 LoadingState GetLoadingState() const;
211 * @brief Returns the URL of the image.
213 * @return The URL of the image file.
215 std::string GetUrl() const;
218 * @brief Reload image from filesystem.
220 * The set ImageAttributes are used when requesting the image again.
221 * @note if Image is offstage and OnDemand policy is set, reload request is ignored.
226 * @brief Get the attributes of an image.
228 * Only to be used after the image has finished loading.
229 * (Ticket's LoadingSucceeded callback was called)
230 * The returned value will reflect the true image dimensions once the asynchronous loading has finished.
231 * Connect to SignalLoadingFinished or use GetLoadingState to make sure this value is actual.
232 * @pre image should be loaded
233 * @return a copy of the attributes
235 ImageAttributes GetAttributes() const;
240 * @brief Emitted when the image data loads successfully, or when the loading fails.
242 * @return A signal object to Connect() with.
244 ResourceImageSignal& LoadingFinishedSignal();
246 public: // Not intended for application developers
248 explicit DALI_INTERNAL ResourceImage( Internal::ResourceImage* );
253 #endif // __DALI_RESOURCE_IMAGE_H__