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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef HW_EMULATOR_CAMERA_PREVIEW_WINDOW_H
     18 #define HW_EMULATOR_CAMERA_PREVIEW_WINDOW_H
     19 
     20 /*
     21  * Contains declaration of a class PreviewWindow that encapsulates functionality
     22  * of a preview window set via set_preview_window camera HAL API.
     23  */
     24 
     25 namespace android {
     26 
     27 class EmulatedCameraDevice;
     28 
     29 /* Encapsulates functionality of a preview window set via set_preview_window
     30  * camera HAL API.
     31  *
     32  * Objects of this class are contained in EmulatedCamera objects, and handle
     33  * relevant camera API callbacks.
     34  */
     35 class PreviewWindow {
     36 public:
     37     /* Constructs PreviewWindow instance. */
     38     PreviewWindow();
     39 
     40     /* Destructs PreviewWindow instance. */
     41     ~PreviewWindow();
     42 
     43     /***************************************************************************
     44      * Camera API
     45      **************************************************************************/
     46 
     47 public:
     48     /* Actual handler for camera_device_ops_t::set_preview_window callback.
     49      * This method is called by the containing emulated camera object when it is
     50      * handing the camera_device_ops_t::set_preview_window callback.
     51      * Param:
     52      *  window - Preview window to set. This parameter might be NULL, which
     53      *      indicates preview window reset.
     54      *  preview_fps - Preview's frame frequency. This parameter determins when
     55      *      a frame received via onNextFrameAvailable call will be pushed to
     56      *      the preview window. If 'window' parameter passed to this method is
     57      *      NULL, this parameter is ignored.
     58      * Return:
     59      *  NO_ERROR on success, or an appropriate error status.
     60      */
     61     status_t setPreviewWindow(struct preview_stream_ops* window,
     62                               int preview_fps);
     63 
     64     /* Starts the preview.
     65      * This method is called by the containing emulated camera object when it is
     66      * handing the camera_device_ops_t::start_preview callback.
     67      */
     68     status_t startPreview();
     69 
     70     /* Stops the preview.
     71      * This method is called by the containing emulated camera object when it is
     72      * handing the camera_device_ops_t::start_preview callback.
     73      */
     74     void stopPreview();
     75 
     76     /* Checks if preview is enabled. */
     77     inline bool isPreviewEnabled()
     78     {
     79         return mPreviewEnabled;
     80     }
     81 
     82     /****************************************************************************
     83      * Public API
     84      ***************************************************************************/
     85 
     86 public:
     87     /* Next frame is available in the camera device.
     88      * This is a notification callback that is invoked by the camera device when
     89      * a new frame is available. The frame is available through the |camera_dev|
     90      * object. Remember to use an EmulatedCameraDevice::FrameLock object to
     91      * protect access to the frame while using it.
     92      * Note that most likely this method is called in context of a worker thread
     93      * that camera device has created for frame capturing.
     94      * Param:
     95      * timestamp - Frame's timestamp.
     96      * camera_dev - Camera device instance that delivered the frame.
     97      */
     98     void onNextFrameAvailable(nsecs_t timestamp,
     99                               EmulatedCameraDevice* camera_dev);
    100 
    101     /***************************************************************************
    102      * Private API
    103      **************************************************************************/
    104 
    105 protected:
    106     /* Adjusts cached dimensions of the preview window frame according to the
    107      * frame dimensions used by the camera device.
    108      *
    109      * When preview is started, it's not known (hard to define) what are going
    110      * to be the dimensions of the frames that are going to be displayed. Plus,
    111      * it might be possible, that such dimensions can be changed on the fly. So,
    112      * in order to be always in sync with frame dimensions, this method is
    113      * called for each frame passed to onNextFrameAvailable method, in order to
    114      * properly adjust frame dimensions, used by the preview window.
    115      * Note that this method must be called while object is locked.
    116      * Param:
    117      *  camera_dev - Camera device, prpviding frames displayed in the preview
    118      *      window.
    119      * Return:
    120      *  true if cached dimensions have been adjusted, or false if cached
    121      *  dimensions match device's frame dimensions.
    122      */
    123     bool adjustPreviewDimensions(EmulatedCameraDevice* camera_dev);
    124 
    125     /***************************************************************************
    126      * Data members
    127      **************************************************************************/
    128 
    129 protected:
    130     /* Locks this instance for data changes. */
    131     Mutex                           mObjectLock;
    132 
    133     /* Preview window instance. */
    134     preview_stream_ops*             mPreviewWindow;
    135 
    136     /*
    137      * Cached preview window frame dimensions.
    138      */
    139 
    140     int                             mPreviewFrameWidth;
    141     int                             mPreviewFrameHeight;
    142 
    143     /* Preview status. */
    144     bool                            mPreviewEnabled;
    145 };
    146 
    147 }; /* namespace android */
    148 
    149 #endif  /* HW_EMULATOR_CAMERA_PREVIEW_WINDOW_H */
    150