Vibration API: plumbing from Blink to Java.

content/browser/vibration/vibration_message_filter.cc

+// Copyright (c) 2013 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.
+
+#include "content/browser/vibration/vibration_message_filter.h"
+
+#include <algorithm>
+
+#include "content/common/view_messages.h"
+
+#if defined(OS_ANDROID)
+#include "jni/VibrationMessageFilter_jni.h"
+
+using base::android::AttachCurrentThread;
+#endif
+
+namespace content {
+
+// Minimum duration of a vibration is 1 millisecond.
+const int64 kMinimumVibrationDurationMs = 1;
+
+// Maximum duration of a vibration is 10 seconds.
+const int64 kMaximumVibrationDurationMs = 10000;
+
+
+VibrationMessageFilter::VibrationMessageFilter() {
+}
+
+VibrationMessageFilter::~VibrationMessageFilter() {
+#if defined(OS_ANDROID)
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  OnCancelVibration();
+#endif
+}
+
+#if defined(OS_ANDROID)
+// static
+bool VibrationMessageFilter::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+#endif
+
+bool VibrationMessageFilter::OnMessageReceived(
+    const IPC::Message& message,
+    bool* message_was_ok) {
+  bool handled = true;
+#if defined(OS_ANDROID)
+  IPC_BEGIN_MESSAGE_MAP_EX(VibrationMessageFilter,
+                           message,
+                           *message_was_ok)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_Vibrate, OnVibrate)
+    IPC_MESSAGE_HANDLER(ViewHostMsg_CancelVibration, OnCancelVibration)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP_EX()
+#endif
+  return handled;
+}
+
+#if defined(OS_ANDROID)
+void VibrationMessageFilter::OnVibrate(int64 milliseconds) {
+  // Though the Blink implementation already sanitizes vibration times, don't
+  // trust any values passed from the renderer.
+  milliseconds = std::max(kMinimumVibrationDurationMs,
+      std::min(milliseconds, kMaximumVibrationDurationMs));
+  initializeJava();
+  Java_VibrationMessageFilter_vibrate(AttachCurrentThread(),
+                                j_vibration_message_filter_.obj(),
+                                milliseconds);
+}
+
+void VibrationMessageFilter::OnCancelVibration() {
+  initializeJava();
+  Java_VibrationMessageFilter_cancelVibration(AttachCurrentThread(),
+                                        j_vibration_message_filter_.obj());
+}
+
+void VibrationMessageFilter::initializeJava() {

[jam, 2013/07/03 16:51:55]

why do you need this method? i.e. won't OnVibrate always be called first? so we
can do the lazy initialization there?

[Michael van Ouwerkerk, 2013/07/10 15:24:26]

Done. It does look like it's safe to assume cancel is never called first, as
NavigatorVibration.cpp checks whether it is currently vibrating before sending
the cancel message.

+  if (j_vibration_message_filter_.is_null()) {
+    j_vibration_message_filter_.Reset(
+        Java_VibrationMessageFilter_create(
+            AttachCurrentThread(),
+            base::android::GetApplicationContext()));
+  }
+}
+#endif
+
+}  // namespace content