Change the cpp wrappers of audio input/video capture to use CompletionCallbackWithOutput.

ppapi/cpp/dev/audio_input_dev.h

 // Copyright (c) 2012 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_DEV_AUDIO_INPUT_DEV_H_
 #define PPAPI_CPP_DEV_AUDIO_INPUT_DEV_H_
 
 #include <vector>
 
 #include "ppapi/c/dev/ppb_audio_input_dev.h"
 #include "ppapi/cpp/audio_config.h"
+#include "ppapi/cpp/completion_callback.h"
+#include "ppapi/cpp/dev/device_ref_dev.h"
 #include "ppapi/cpp/resource.h"
 
 namespace pp {
 
-class CompletionCallback;
-class DeviceRef_Dev;
 class InstanceHandle;
 
 class AudioInput_Dev : public Resource {
  public:
   /// An empty constructor for an AudioInput resource.
   AudioInput_Dev();
 
   /// This constructor tries to create an audio input resource using the v0.2
   /// interface, and falls back on the v0.1 interface if that is not available.
   /// Please use the 2-parameter Open() if you used this constructor.
   ///
   /// Note: This constructor is deprecated. Unless your code has to deal with
   /// browsers that only support the v0.1 interface, please use the 1-parameter
   /// constructor instead.
   AudioInput_Dev(const InstanceHandle& instance,
                  const AudioConfig& config,
                  PPB_AudioInput_Callback callback,
                  void* user_data);
 
   /// This constructor uses the v0.2 interface to create an audio input
   /// resource. Please use the 5-parameter Open() if you used this constructor.
   explicit AudioInput_Dev(const InstanceHandle& instance);
 
-  AudioInput_Dev(const AudioInput_Dev& other);
-
   virtual ~AudioInput_Dev();
 
-  AudioInput_Dev& operator=(const AudioInput_Dev& other);
-
   /// Static function for determining whether the browser supports the required
   /// AudioInput interface.
   ///
   /// @return true if the interface is available, false otherwise.
   static bool IsAvailable();
 
   /// Getter function for returning the internal <code>PPB_AudioConfig</code>
   /// struct.
   ///
   /// @return A mutable reference to the PPB_AudioConfig struct.
   AudioConfig& config() { return config_; }
 
   /// Getter function for returning the internal <code>PPB_AudioConfig</code>
   /// struct.
   ///
   /// @return A const reference to the internal <code>PPB_AudioConfig</code>
   /// struct.
   const AudioConfig& config() const { return config_; }
 
-  /// |devices| must stay alive until either this AudioInput_Dev object goes
-  /// away or |callback| is run, if this method returns PP_OK_COMPLETIONPENDING.
-  int32_t EnumerateDevices(std::vector<DeviceRef_Dev>* devices,
-                           const CompletionCallback& callback);
+  // TODO(yzshen, brettw): If we forward declare DeviceRef_Dev (as opposed to
+  // including its .h file), it still compiles. However, it is not recognized as
+  // a derived class of Resource and does the wrong thing!
+  // This is due to the limitation of IsBaseOf in ppapi/cpp/output_traits.h. We
+  // need to figure out a way to overcome this problem.
+  int32_t EnumerateDevices(
+      const CompletionCallbackWithOutput<std::vector<DeviceRef_Dev> >&
+          callback);
 
   /// If |device_ref| is null (i.e., is_null() returns true), the default device
   /// will be used.
   /// In order to maintain backward compatibility, this method doesn't have
   /// input parameters config, audio_input_callback and user_data. Instead, it
   /// uses those values stored when the 4-parameter constructor was called.
   ///
   /// Note: This method is deprecated. Unless your code has to deal with
   /// browsers that only support the v0.1 interface, please use the other
   /// Open().
   int32_t Open(const DeviceRef_Dev& device_ref,
                const CompletionCallback& callback);
 
   int32_t Open(const DeviceRef_Dev& device_ref,
                const AudioConfig& config,
                PPB_AudioInput_Callback audio_input_callback,
                void* user_data,
                const CompletionCallback& callback);
 
   bool StartCapture();
   bool StopCapture();
   void Close();
 
  private:
-  struct EnumerateDevicesState;
+  // Heap-allocated data passed to the CallbackConverter for backward

[brettw, 2012/04/03 21:23:03]

I wonder if these can be defined in the ResourceArray_Dev class and exported so
you only need to write this once. I think the implementations in audio input and
the video devices are the same, right? I think the resource arrays were only
ever used for the devices, so putting it there makes sense.

[yzshen1, 2012/04/04 00:36:34]

Thanks for pointing it out! It looks much better as you suggested.
(I don't know why I didn't realize it earlier. Maybe I was in cruise-control
mode at that time. :))

On 2012/04/03 21:23:03, brettw wrote:

+  // compatibility.
+  struct EnumerateCallbackData0_2 {
+    PP_Resource devices;
+    PP_ArrayOutput output;
+    PP_CompletionCallback original_callback;
+  };
 
-  void AbortEnumerateDevices();
-
-  // |user_data| is an EnumerateDevicesState object. It is this method's
-  // responsibility to delete it.
-  static void OnEnumerateDevicesComplete(void* user_data, int32_t result);
+  // This is an adapter to convert the v0.2 EnumerateDevices oputput, which is a

[brettw, 2012/04/03 21:23:03]

oputput

[yzshen1, 2012/04/04 00:36:34]

Done.

+  // PPB_ResourceArray_Dev resource, to PP_ArrayOutput that the caller is
+  // expecting.
+  //
+  // This takes a heap-allocated EnumerateCallbackData0_2 struct passed as the
+  // user data and deletes it when the call completes.
+  static void CallbackConverter(void* user_data, int32_t result);
 
   AudioConfig config_;
 
-  // It is set in EnumerateDevices(), and cleared in AbortEnumerateDevices() or
-  // OnEnumerateDevicesComplete(). The object will be deleted by
-  // OnEnumerateDevicesComplete().
-  EnumerateDevicesState* enum_state_;
-
   // Used to store the arguments of Open() for the v0.2 interface.
   PPB_AudioInput_Callback audio_input_callback_;
   void* user_data_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_DEV_AUDIO_INPUT_DEV_H_