Bug 1201590 - WebMIDI Utility classes; r=baku,padenot

MozReview-Commit-ID: 8TAO1dcdK5E

--HG--
extra : rebase_source : 4e28bd94c5aec3e4cf9642a597b624a7fb14bd09

dom/midi/MIDIPortInterface.cpp

@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/MIDIPortInterface.h"
+#include "mozilla/dom/MIDIPlatformService.h"
+#include "mozilla/dom/MIDITypes.h"
+
+MIDIPortInterface::MIDIPortInterface(const MIDIPortInfo& aPortInfo, bool aSysexEnabled) :
+  mId(aPortInfo.id()),
+  mName(aPortInfo.name()),
+  mManufacturer(aPortInfo.manufacturer()),
+  mVersion(aPortInfo.version()),
+  mSysexEnabled(aSysexEnabled),
+  mType((MIDIPortType)aPortInfo.type()),
+  // We'll never initialize a port object that's not connected
+  mDeviceState(MIDIPortDeviceState::Connected),
+  // Open everything on connection
+  mConnectionState(MIDIPortConnectionState::Open),
+  mShuttingDown(false)
+{
+}
+
+MIDIPortInterface::~MIDIPortInterface()
+{
+  Shutdown();
+}
+
+void
+MIDIPortInterface::Shutdown()
+{
+  mShuttingDown = true;
+}
+

dom/midi/MIDIPortInterface.h

@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_MIDIPortInterface_h
+#define mozilla_dom_MIDIPortInterface_h
+
+#include "nsIObserver.h"
+#include "mozilla/dom/MIDIPortBinding.h"
+
+namespace mozilla {
+namespace dom {
+class MIDIPortInfo;
+/**
+ * Base class for MIDIPort Parent/Child Actors. Makes sure both sides of the
+ * MIDIPort IPC connection need to a synchronized set of info/state.
+ *
+ */
+class MIDIPortInterface
+{
+public:
+  MIDIPortInterface(const MIDIPortInfo& aPortInfo, bool aSysexEnabled);
+  const nsString& Id() const { return mId; }
+  const nsString& Name() const { return mName; }
+  const nsString& Manufacturer() const { return mManufacturer; }
+  const nsString& Version() const { return mVersion; }
+  bool SysexEnabled() const { return mSysexEnabled; }
+  MIDIPortType Type() const { return mType; }
+  MIDIPortDeviceState DeviceState() const { return mDeviceState; }
+  MIDIPortConnectionState ConnectionState() const { return mConnectionState; }
+  bool IsShutdown() const { return mShuttingDown; }
+  virtual void Shutdown();
+protected:
+  virtual ~MIDIPortInterface();
+  nsString mId;
+  nsString mName;
+  nsString mManufacturer;
+  nsString mVersion;
+  bool mSysexEnabled;
+  MIDIPortType mType;
+  MIDIPortDeviceState mDeviceState;
+  MIDIPortConnectionState mConnectionState;
+  bool mShuttingDown;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_MIDIPortInterface_h

dom/midi/MIDIUtils.cpp

@@ -0,0 +1,131 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/MIDITypes.h"
+#include "mozilla/dom/MIDIUtils.h"
+
+// Taken from MIDI IMPLEMENTATION CHART INSTRUCTIONS, MIDI Spec v1.0, Pg. 97
+static const uint8_t kCommandByte = 0x80;
+static const uint8_t kSysexMessageStart = 0xF0;
+static const uint8_t kSystemMessage = 0xF0;
+static const uint8_t kSysexMessageEnd = 0xF7;
+static const uint8_t kSystemRealtimeMessage = 0xF8;
+// Represents the length of all possible command messages.
+// Taken from MIDI Spec, Pg. 101v 1.0, Table 2
+static const uint8_t kCommandLengths[] = {3, 3, 3, 3, 2, 2, 3};
+// Represents the length of all possible system messages. The length of sysex
+// messages is variable, so we just put zero since it won't be checked anyways.
+// Taken from MIDI Spec v1.0, Pg. 105, Table 5
+static const uint8_t kSystemLengths[] = {0, 2, 3, 2, 1, 1, 1, 1};
+
+namespace mozilla {
+namespace dom {
+namespace MIDIUtils {
+
+// Checks validity of MIDIMessage passed to it. Throws debug warnings and
+// returns false if message is not valid.
+bool
+IsValidMessage(const MIDIMessage* aMsg)
+{
+  if (NS_WARN_IF(!aMsg)) {
+    return false;
+  }
+  // Assert on parser problems
+  MOZ_ASSERT(aMsg->data().Length() > 0,
+             "Created a MIDI Message of Length 0. This should never happen!");
+  uint8_t cmd = aMsg->data()[0];
+  // If first byte isn't a command, something is definitely wrong.
+  MOZ_ASSERT((cmd & kCommandByte) == kCommandByte,
+             "Constructed a MIDI packet where first byte is not command!");
+  if (cmd == kSysexMessageStart) {
+    // All we can do with sysex is make sure it starts and  ends with the correct
+    // command bytes.
+    if (aMsg->data()[aMsg->data().Length() - 1] != kSysexMessageEnd) {
+      NS_WARNING("Last byte of Sysex Message not 0xF7!");
+      return false;
+    }
+    return true;
+  }
+  // For system realtime messages, the length should always be 1.
+  if ((cmd & kSystemRealtimeMessage) == kSystemRealtimeMessage) {
+    return aMsg->data().Length() == 1;
+  }
+  // Otherwise, just use the correct array for testing lengths. We can't tell
+  // much about message validity other than that.
+  if ((cmd & kSystemMessage) == kSystemMessage) {
+    if (cmd - kSystemMessage >= static_cast<uint8_t>(ArrayLength(kSystemLengths))) {
+      NS_WARNING("System Message Command byte not valid!");
+      return false;
+    }
+    return aMsg->data().Length() == kSystemLengths[cmd - kSystemMessage];
+  }
+  // For non system commands, we only care about differences in the high nibble
+  // of the first byte. Shift this down to give the index of the expected packet
+  // length.
+  uint8_t cmdIndex = (cmd - kCommandByte) >> 4;
+  if (cmdIndex >= ArrayLength(kCommandLengths)) {
+    // If our index is bigger than our array length, command byte is unknown;
+    NS_WARNING("Unknown MIDI command!");
+    return false;
+  }
+  return aMsg->data().Length() == kCommandLengths[cmdIndex];
+}
+
+uint32_t
+ParseMessages(const nsTArray<uint8_t>& aByteBuffer,
+              const TimeStamp& aTimestamp,
+              nsTArray<MIDIMessage>& aMsgArray)
+{
+  uint32_t bytesRead = 0;
+  bool inSysexMessage = false;
+  nsAutoPtr<MIDIMessage> currentMsg;
+  for (auto& byte : aByteBuffer) {
+    bytesRead++;
+    if ((byte & kSystemRealtimeMessage) == kSystemRealtimeMessage) {
+      MIDIMessage rt_msg;
+      rt_msg.data().AppendElement(byte);
+      rt_msg.timestamp() = aTimestamp;
+      aMsgArray.AppendElement(rt_msg);
+      continue;
+    }
+    if (byte == kSysexMessageEnd) {
+      if (!inSysexMessage) {
+        MOZ_ASSERT(inSysexMessage);
+        NS_WARNING("Got sysex message end with no sysex message being processed!");
+      }
+      inSysexMessage = false;
+    } else if (byte & kCommandByte) {
+      if (currentMsg && IsValidMessage(currentMsg)) {
+        aMsgArray.AppendElement(*currentMsg);
+      }
+      currentMsg = new MIDIMessage();
+      currentMsg->timestamp() = aTimestamp;
+    }
+    currentMsg->data().AppendElement(byte);
+    if (byte == kSysexMessageStart) {
+      inSysexMessage = true;
+    }
+  }
+  if (currentMsg && IsValidMessage(currentMsg)) {
+    aMsgArray.AppendElement(*currentMsg);
+  }
+  return bytesRead;
+}
+
+bool
+IsSysexMessage(const MIDIMessage& aMsg)
+{
+  if (aMsg.data().Length() == 0) {
+    return false;
+  }
+  if (aMsg.data()[0] == kSysexMessageStart) {
+    return true;
+  }
+  return false;
+}
+}
+} // namespace dom
+} // namespace mozilla

dom/midi/MIDIUtils.h

@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsTArray.h"
+#include "mozilla/TimeStamp.h"
+
+namespace mozilla {
+namespace dom {
+class MIDIMessage;
+
+/**
+ * Set of utility functions for dealing with MIDI Messages.
+ *
+ */
+namespace MIDIUtils {
+
+// Takes a nsTArray of bytes and parses it into zero or more MIDI messages.
+// Returns number of bytes parsed.
+uint32_t ParseMessages(const nsTArray<uint8_t>& aByteBuffer,
+                       const TimeStamp& aTimestamp,
+                       nsTArray<MIDIMessage>& aMsgArray);
+// Returns true if a message is a sysex message.
+bool IsSysexMessage(const MIDIMessage& a);
+}
+} // namespace dom
+} // namespace mozilla

modules/libpref/init/all.js

@@ -225,6 +225,9 @@ pref("dom.keyboardevent.dispatch_during_composition", false);
 // cause inputting printable character.
 pref("dom.keyboardevent.keypress.dispatch_non_printable_keys_only_system_group_in_content", false);
 
+// Whether the WebMIDI API is enabled
+pref("dom.webmidi.enabled", false);
+
 // Whether to run add-on code in different compartments from browser code. This
 // causes a separate compartment for each (addon, global) combination, which may
 // significantly increase the number of compartments in the system.