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// Copyright (c) 2011 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 WEBKIT_PLUGINS_PPAPI_MESSAGE_CHANNEL_H_
#define WEBKIT_PLUGINS_PPAPI_MESSAGE_CHANNEL_H_
#include "base/task.h"
#include "ppapi/shared_impl/resource.h"
#include "third_party/npapi/bindings/npruntime.h"
struct PP_Var;
namespace webkit {
namespace ppapi {
class PluginInstance;
// MessageChannel implements bidirectional postMessage functionality, allowing
// calls from JavaScript to plugins and vice-versa. See
// PPB_Messaging::PostMessage and PPP_Messaging::HandleMessage for more
// information.
//
// Currently, only 1 MessageChannel can exist, to implement postMessage
// functionality for the instance interfaces. In the future, when we create a
// MessagePort type in PPAPI, those may be implemented here as well with some
// refactoring.
// - Separate message ports won't require the passthrough object.
// - The message target won't be limited to instance, and should support
// either plugin-provided or JS objects.
// TODO(dmichael): Add support for separate MessagePorts.
class MessageChannel {
public:
// MessageChannelNPObject is a simple struct that adds a pointer back to a
// MessageChannel instance. This way, we can use an NPObject to allow
// JavaScript interactions without forcing MessageChannel to inherit from
// NPObject.
struct MessageChannelNPObject : public NPObject {
MessageChannelNPObject();
~MessageChannelNPObject();
MessageChannel* message_channel;
};
explicit MessageChannel(PluginInstance* instance);
~MessageChannel();
// Post a message to the onmessage handler for this channel's instance
// asynchronously.
void PostMessageToJavaScript(PP_Var message_data);
// Post a message to the PPP_Instance HandleMessage function for this
// channel's instance.
void PostMessageToNative(PP_Var message_data);
// Return the NPObject* to which we should forward any calls which aren't
// related to postMessage. Note that this can be NULL; it only gets set if
// there is a scriptable 'InstanceObject' associated with this channel's
// instance.
NPObject* passthrough_object() {
return passthrough_object_;
}
void SetPassthroughObject(NPObject* passthrough);
NPObject* np_object() { return np_object_; }
PluginInstance* instance() {
return instance_;
}
private:
PluginInstance* instance_;
// We pass all non-postMessage calls through to the passthrough_object_.
// This way, a plugin can use PPB_Class or PPP_Class_Deprecated and also
// postMessage. This is necessary to support backwards-compatibility, and
// also trusted plugins for which we will continue to support synchronous
// scripting.
NPObject* passthrough_object_;
// The NPObject we use to expose postMessage to JavaScript.
MessageChannelNPObject* np_object_;
// An NPVariant referring to the JavaScript function we use to send a message
// to a JavaScript target.
NPVariant onmessage_invoker_;
// Evaluates the JavaScript code for onmessage_invoker_ and makes
// it a callable NPVariant for that function. Returns true on success, false
// otherwise.
bool EvaluateOnMessageInvoker();
// Post a message to the onmessage handler for this channel's instance
// synchronously. This is used by PostMessageToJavaScript.
void PostMessageToJavaScriptImpl(PP_Var message_data);
// Post a message to the PPP_Instance HandleMessage function for this
// channel's instance. This is used by PostMessageToNative.
void PostMessageToNativeImpl(PP_Var message_data);
// Ensure pending tasks will not fire after this object is destroyed.
ScopedRunnableMethodFactory<MessageChannel> method_factory_;
DISALLOW_COPY_AND_ASSIGN(MessageChannel);
};
} // namespace ppapi
} // namespace webkit
#endif // WEBKIT_PLUGINS_PPAPI_MESSAGE_CHANNEL_H_
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