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>
28 #include <dali/devel-api/images/image-operations.h>
33 namespace Internal DALI_INTERNAL
39 * @brief ResourceImage is an image loaded using a URL
41 * <h3>ResourceImage Loading</h3>
43 * When the ResourceImage is created, resource loading will be attempted unless
44 * the ResourceImage is created with IMMEDIATE loading policy or a compatible resource is found in cache.
45 * In case of loading images ON_DEMAND, resource loading will only be attempted if the associated ImageActor
47 * Scaling of images to a desired smaller size can be requested by providing desired dimensions,
48 * scaling mode and filter mode to 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, filter mode, and orientation compensation can be set when requesting an image.
60 * <i>Compatible resources</i>
62 * Before loading a new ResourceImage the internal image resource cache is checked by dali.
63 * If there is an image already loaded in memory and is deemed "compatible" with the requested image,
64 * that resource is reused.
65 * This happens for example if a loaded image exists with the same URL, scaling and filtering modes,
66 * and the difference between both of the dimensions is less than a few pixels.
68 * <i>Reloading images</i>
70 * The same request used on creating the ResourceImage is re-issued when reloading images.
71 * If the file changed since the last load operation, this might result in a different resource.
72 * Reload only takes effect if both of these conditions apply:
73 * - The ResourceImage has already finished loading
74 * - The ResourceImage is either on Stage or using IMMEDIATE load policy
77 * | %Signal Name | Method |
78 * |------------------------|------------------------------|
79 * | image-loading-finished | @ref LoadingFinishedSignal() |
81 class DALI_IMPORT_API ResourceImage : public Image
85 * @brief Resource management options.
89 * @brief LoadPolicy controls the way images are loaded into memory.
93 IMMEDIATE, ///< load image once it is created (default)
94 ON_DEMAND ///< delay loading until the image is being used (a related actor is added to Stage)
98 * @brief Type of signal for LoadingFinished and Uploaded.
100 typedef Signal< void (ResourceImage) > ResourceImageSignal;
105 * @brief Get the size of an image from disk.
107 * This function will read the header info from file on disk and is
108 * synchronous, so it should not be used repeatedly or in tight
111 * @param [in] url The URL of the image file.
112 * @return The width and height in pixels of the image.
114 static ImageDimensions GetImageSize( const std::string& url );
117 * @brief Constructor which creates an empty ResourceImage object.
119 * Use ResourceImage::New(...) to create an initialised object.
126 * This is non-virtual since derived Handle types must not contain data or virtual methods.
131 * @brief This copy constructor is required for (smart) pointer semantics.
133 * @param [in] handle A reference to the copied handle
135 ResourceImage( const ResourceImage& handle );
138 * @brief This assignment operator is required for (smart) pointer semantics.
140 * @param [in] rhs A reference to the copied handle
141 * @return A reference to this
143 ResourceImage& operator=( const ResourceImage& rhs );
146 * @name ResourceImageFactoryFunctions
147 * Create ResourceImage object instances using these functions.
152 * @brief Create an initialised ResourceImage object.
154 * Uses defaults for all options.
156 * @sa Dali::FittingMode::Type Dali::SamplingMode::Type
157 * @param [in] url The URL of the image file to use.
158 * @param [in] orientationCorrection Reorient the image to respect any orientation metadata in its header.
159 * @return A handle to a newly allocated object
161 static ResourceImage New( const std::string& url, bool orientationCorrection = true );
164 * @brief Create an initialised ResourceImage object.
166 * @param [in] url The URL of the image file to use.
167 * @param [in] loadPol The LoadPolicy to apply when loading the image resource.
168 * @param [in] releasePol The ReleasePolicy to apply to Image.
169 * @param [in] orientationCorrection Reorient the image to respect any orientation metadata in its header.
170 * @return A handle to a newly allocated object
172 static ResourceImage New( const std::string& url, LoadPolicy loadPol, ReleasePolicy releasePol, bool orientationCorrection = true );
175 * @brief Create an initialised ResourceImage object.
177 * @param [in] url The URL of the image file to use.
178 * @param [in] size The width and height to fit the loaded image to.
179 * @param [in] fittingMode The method used to fit the shape of the image before loading to the shape defined by the size parameter.
180 * @param [in] samplingMode The filtering method used when sampling pixels from the input image while fitting it to desired size.
181 * @param [in] orientationCorrection Reorient the image to respect any orientation metadata in its header.
182 * @return A handle to a newly allocated object
184 static ResourceImage New( const std::string& url,
185 ImageDimensions size,
186 FittingMode::Type fittingMode = FittingMode::DEFAULT,
187 SamplingMode::Type samplingMode = SamplingMode::DEFAULT,
188 bool orientationCorrection = true );
191 * @brief Create an initialised ResourceImage object.
193 * @param [in] url The URL of the image file to use.
194 * @param [in] loadPol The LoadPolicy to apply when loading the image resource.
195 * @param [in] releasePol The ReleasePolicy to apply to Image.
196 * @param [in] size The width and height to fit the loaded image to.
197 * @param [in] fittingMode The method used to fit the shape of the image before loading to the shape defined by the size parameter.
198 * @param [in] samplingMode The filtering method used when sampling pixels from the input image while fitting it to desired size.
199 * @param [in] orientationCorrection Reorient the image to respect any orientation metadata in its header.
200 * @return A handle to a newly allocated object
202 static ResourceImage New( const std::string& url,
204 ReleasePolicy releasePol,
205 ImageDimensions size,
206 FittingMode::Type fittingMode = FittingMode::DEFAULT,
207 SamplingMode::Type samplingMode = SamplingMode::DEFAULT,
208 bool orientationCorrection = true );
213 * @brief Downcast an Object handle to ResourceImage handle.
215 * If handle points to a ResourceImage object the
216 * downcast produces valid handle. If not the returned handle is left uninitialized.
217 * @param[in] handle to An object
218 * @return handle to a Image object or an uninitialized handle
220 static ResourceImage DownCast( BaseHandle handle );
223 * @brief Return load policy.
225 * @return resource load policy
227 LoadPolicy GetLoadPolicy() const;
230 * @brief Query whether the image data has loaded.
232 * The asynchronous loading begins when the Image object is created.
233 * After the Image object is discarded, the image data will be released from memory.
234 * @return The loading state, either Loading, Success or Failed.
236 LoadingState GetLoadingState() const;
239 * @brief Returns the URL of the image.
241 * @return The URL of the image file.
243 std::string GetUrl() const;
246 * @brief Reload image from filesystem.
248 * The original set of image loading attributes (requested dimensions, scaling
249 * mode and filter mode) are used when requesting the image again.
250 * @note If image is offstage and OnDemand policy is set, the reload request is
258 * @brief Emitted when the image data loads successfully, or when the loading fails.
260 * @return A signal object to Connect() with.
262 ResourceImageSignal& LoadingFinishedSignal();
264 public: // Not intended for application developers
266 explicit DALI_INTERNAL ResourceImage( Internal::ResourceImage* );
271 #endif // __DALI_RESOURCE_IMAGE_H__