Pepper: add Image Capture interfaces.

ppapi/cpp/private/image_capture_private.h

+/* Copyright 2014 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef PPAPI_CPP_PRIVATE_IMAGE_CAPTURE_PRIVATE_H_
+#define PPAPI_CPP_PRIVATE_IMAGE_CAPTURE_PRIVATE_H_
+
+#include "ppapi/c/private/ppb_image_capture_private.h"
+#include "ppapi/cpp/completion_callback.h"
+#include "ppapi/cpp/private/image_capture_config_private.h"

[Justin Chuang, 2014/08/14 16:33:45]

need *capabilities_private.h?

[wuchengli, 2014/08/15 08:18:01]

Done.

+#include "ppapi/cpp/resource.h"
+#include "ppapi/cpp/var.h"
+
+/// @file
+/// Defines the <code>ImageCapture_Private</code> interface. Used for
+/// acquiring a single still image from a camera source.
+namespace pp {
+
+/// To capture a still image with this class, use the following steps.
+/// 1. Get a ImageCapture_Private object by Create().

[Justin Chuang, 2014/08/14 16:33:46]

No Create() in C++.

[wuchengli, 2014/08/15 08:18:01]

Done.

+/// 2. Call GetCameraCapabilities to get the supported preview sizes.
+/// 3. For optimal performance, set one of the supported preview size as the
+///    constraints of getUserMedia. Use the created MediaStreamVideoTrack for
+///    camera previews.
+/// 4. Set the same preview size and other settings by SetConfig.
+/// 5. Call CaptureStillImage to capture a still image. Play the shutter sound
+///    in the shutter callback. The image from the preview callback can be used
+///    for display. JPEG image will be returned to the JPEG callback.
+class ImageCapture_Private {
+ public:
+  /// Default constructor for creating an is_null()
+  /// <code>ImageCapture_Private</code> object.
+  ImageCapture_Private();
+
+  /// Creates a ImageCapture_Private resource.

[Justin Chuang, 2014/08/14 16:33:45]

s/a/an/

[wuchengli, 2014/08/15 08:18:01]

Done.

+  ///
+  /// @param[in] instance A <code>PP_Instance</code> identifying one instance
+  /// of a module.
+  /// @param[in] camera_source_id A <code>Var</code> identifying a camera
+  /// source. The type is string. The ID can be obtained from
+  /// MediaStreamTrack.getSources() or MediaStreamVideoTrack.id. If a
+  /// MediaStreamVideoTrack is associated with the same source and the track
+  /// is closed, this ImageCapture_Private object can still do image capture.
+  /// @param[in] error_callback A <code>ImageCapture_Private_ErrorCallback
+  /// </code> callback to indicate the image capture has failed.
+  /// @param[inout] user_data An opaque pointer that will be passed to the
+  /// callbacks of ImageCapture_Private.
+  ///
+  /// @return A <code>Resource</code> corresponding to a
+  /// ImageCapture_Private resource if successful, 0 if failed.
+  ImageCapture_Private(const InstanceHandle& instance,
+                       const Var& camera_source_id,
+                       PPB_ImageCapture_Private_ErrorCallback error_callback,
+                       void* user_data);
+
+  /// The copy constructor for <code>ImageCapture_Private</code>.
+  ///
+  /// @param[in] other A reference to a <code>ImageCapture_Private
+  /// </code>.
+  ImageCapture_Private(const ImageCapture_Private& other);

[Justin Chuang, 2014/08/14 16:33:45]

nit: Supporting copy constructor for this class may be a headache. Same for the
rest constructors below.
I don't know how to implement them correctly.

[wuchengli, 2014/08/15 08:18:01]

Removed. I checked and many ppapi cpp classes do not have copy constructor.

+
+  /// Constructs a <code>ImageCapture_Private</code> from a <code>
+  /// Resource</code>.
+  ///
+  /// @param[in] resource A <code>ImageCapture_Private</code>
+  /// resource.
+  explicit ImageCapture_Private(const Resource& resource);
+
+  /// A constructor used when you have received a <code>PP_Resource</code> as a
+  /// return value that has had 1 ref added for you.
+  ///
+  /// @param[in] resource A <code>ImageCapture_Private</code>
+  /// resource.
+  ImageCapture_Private(PassRef, PP_Resource resource);
+
+  // Destructor.
+  ~ImageCapture_Private();
+
+  /// Disconnects from the camera and cancels all pending capture requests.
+  /// After this returns, no callbacks will be called. If <code>
+  /// ImageCapture_Private</code> is destroyed and is not closed yet, this
+  /// function will be automatically called. Calling this more than once has no
+  /// effect.
+  ///
+  /// @param[in] image_capture A <code>Resource</code> corresponding to an
+  /// image capture resource.

[Justin Chuang, 2014/08/14 16:33:45]

redundant @param

[wuchengli, 2014/08/15 08:18:01]

Done.

+  /// @param[in] callback <code>CompletionCallback</code> to be called upon
+  /// completion of <code>Close()</code>.
+  ///
+  /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
+  int32_t Close(const CompletionCallback& callback);
+
+  /// Sets the configuration of the image capture.
+  /// If <code>SetConfig()</code> is not called, default settings will be used.
+  ///
+  /// @param[in] image_capture A <code>Resource</code> corresponding to an
+  /// image capture resource.

[Justin Chuang, 2014/08/14 16:33:45]

redundant @param

[wuchengli, 2014/08/15 08:18:01]

Done.

+  /// @param[in] config A <code>PP_ImageCaptureConfig_Private</code> object.
+  /// @param[in] callback <code>CompletionCallback</code> to be called upon
+  /// completion of <code>SetConfig()</code>.
+  ///
+  /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
+  /// Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of
+  /// <code>SetConfig()</code> or <code>CaptureStillImage()</code>.
+  /// If an error is returned, the configuration will not be changed.
+  int32_t SetConfig(const ImageCaptureConfig_Private& config,
+                    const CompletionCallback& callback);
+
+  /// Gets the configuration of the image capture.
+  ///
+  /// @param[out] config A <code>PP_ImageCaptureConfig_Private</code> for
+  /// storing the current image capture config on success. Otherwise, the values
+  /// will not be changed.
+  /// @param[in] callback <code>CompletionCallback</code> to be called upon
+  /// completion of <code>GetConfig()</code>.
+  ///
+  /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
+  int32_t GetConfig(ImageCaptureConfig_Private* config,
+                    const CompletionCallback& callback);

[Justin Chuang, 2014/08/14 16:33:46]

Can replace both arguments with 

const CompletionCallbackWithOutput<ImageCaptureConfig_Private>& callback

More C++-ish, but it will copy the *Config* object. Overheads may be
neglectable.

[wuchengli, 2014/08/15 08:18:01]

Done.

+
+  /// Gets the camera capabilities.
+  ///
+  /// The camera capabilities do not change for a given camera source.
+  ///
+  /// @param[out] capabilities A <code>CameraCapabilities_Private</code> for
+  /// storing the image capture capabilities on success. Otherwise, the value
+  /// will not be changed.
+  /// @param[in] callback <code>CompletionCallback</code> to be called upon
+  /// completion of <code>GetCameraCapabilities()</code>.
+  ///
+  /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
+  int32_t GetCameraCapabilities(CameraCapabilities_Private* capabilities,
+                                const CompletionCallback& callback);

[Justin Chuang, 2014/08/14 16:33:45]

Can replace both arguments with 

const CompletionCallbackWithOutput<CameraCapabilities_Private>& callback

More C++-ish, but it will copy the *Capabilities* object. Overheads may be
neglectable.

[wuchengli, 2014/08/15 08:18:01]

Done.

+
+  /// Captures a still JPEG image from the camera.
+  ///
+  /// Triggers an asynchronous image capture. The camera will initiate a series
+  /// of callbacks to the application as the image capture progresses. The
+  /// callbacks will be invoked in the order of shutter callback, preview
+  /// callback, and JPEG callback. The shutter callback occurs after the image
+  /// is captured. This can be used to trigger a sound to let the user know that
+  /// image has been captured. The preview callback occurs when a scaled, fully
+  /// processed preview image is available. The JPEG callback occurs when the
+  /// compressed image is available. If there is an error after the capture is
+  /// in progress, the error callback passed to <code>
+  /// ImageCapture_Private.Create()</code> will be invoked. All the callbacks
+  /// are invoked by the thread that calls this function.
+  ///
+  /// The size of the preview image in preview callback is determined by
+  /// <code>ImageCaptureConfig_Private.SetPreviewSize</code>. The format is
+  /// decided by the camera and can be got from <code>VideoFrame.GetFormat
+  /// </code>. The size of the JPEG image is determined by <code>
+  /// ImageCaptureConfig_Private.SetJpegSize</code>.
+  ///
+  /// The camera may need to stop and re-start streaming during image capture.
+  /// If some MediaStreamVideoTrack are associated with the camera source, they
+  /// will receive mute and unmute events. The mute event will be received
+  /// before all the callbacks. The unmute event will be received after all the
+  /// callbacks. The preview image will not be sent to the video tracks
+  /// associated with the camera.
+  ///
+  /// @param[in] shutter_callback A <code>
+  /// ImageCapture_Private_ShutterCallback</code> callback to indicate the
+  /// image has been taken.
+  /// @param[in] preview_callback A <code>
+  /// ImageCapture_Private_PreviewCallback</code> callback to return a
+  /// preview of the captured image.
+  /// @param[in] jpeg_callback A <code>
+  /// ImageCapture_Private_JpegCallback</code> callback to return captured
+  /// JPEG image.
+  /// @param[out] sequence_id The sequence ID is a unique monotonically
+  /// increasing value starting from 0, incremented every time a new request
+  /// like image capture is submitted.
+  ///
+  /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
+  /// PP_OK means the callbacks will be triggered. Other values mean the
+  /// callbacks will not be triggered.
+  int32_t CaptureStillImage(
+      const PPB_ImageCapture_Private_ShutterCallback& shutter_callback,

[Justin Chuang, 2014/08/14 16:33:45]

No need to use 'const &'
I think this C++ API can be the same as the C one. It just passes the value of a
function pointer of 4/8 bytes, no performance penalty.
Another problem is  that caller needs to prepare "an instance of *_Callback"
first to be able to pass as a reference. 

[wuchengli, 2014/08/15 08:18:01]

Done.

+      const PPB_ImageCapture_Private_PreviewCallback& preview_callback,
+      const PPB_ImageCapture_Private_JpegCallback& jpeg_callback,
+      int64_t* sequence_id);
+
+  /// Determines if a resource is an image capture resource.
+  ///
+  /// @param[in] resource The <code>Resource</code> to test.
+  ///
+  /// @return True if the given resource is an image capture resource or false
+  /// otherwise.

[Justin Chuang, 2014/08/14 16:33:46]

s/True/true/

[wuchengli, 2014/08/15 08:18:01]

Done.

+  static bool IsImageCapture(const Resource& resource);
+};
+
+} // namespace pp
+
+#endif  /* PPAPI_CPP_PRIVATE_IMAGE_CAPTURE_PRIVATE_H_ */
+