Mac global keybindings

chrome/browser/extensions/global_shortcut_listener_mac.mm

+// 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 "chrome/browser/extensions/global_shortcut_listener_mac.h"
+
+#include <ApplicationServices/ApplicationServices.h>
+#import <Cocoa/Cocoa.h>
+#include <IOKit/hidsystem/ev_keymap.h>
+
+#import "base/mac/foundation_util.h"
+#include "chrome/browser/extensions/api/commands/command_service.h"
+#include "content/public/browser/browser_thread.h"
+#include "ui/base/accelerators/accelerator.h"
+#include "ui/events/event.h"
+#import "ui/events/keycodes/keyboard_code_conversion_mac.h"
+
+using content::BrowserThread;
+using extensions::GlobalShortcutListenerMac;
+
+namespace {
+
+// The media keys subtype. No official docs found, but widely known.
+// http://lists.apple.com/archives/cocoa-dev/2007/Aug/msg00499.html
+const int kSystemDefinedEventMediaKeysSubtype = 8;
+
+ui::KeyboardCode MediaKeyCodeToKeyboardCode(int key_code) {
+  switch (key_code) {
+    case NX_KEYTYPE_PLAY:
+      return ui::VKEY_MEDIA_PLAY_PAUSE;
+    case NX_KEYTYPE_PREVIOUS:
+    case NX_KEYTYPE_REWIND:
+      return ui::VKEY_MEDIA_PREV_TRACK;
+    case NX_KEYTYPE_NEXT:
+    case NX_KEYTYPE_FAST:
+      return ui::VKEY_MEDIA_NEXT_TRACK;
+  }
+  return ui::VKEY_UNKNOWN;
+}
+
+}  // namespace
+
+namespace extensions {
+
+// static
+GlobalShortcutListener* GlobalShortcutListener::GetInstance() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  static GlobalShortcutListenerMac *instance =
+      new GlobalShortcutListenerMac();
+  return instance;
+}
+
+GlobalShortcutListenerMac::GlobalShortcutListenerMac()
+    : is_listening_(false),
+      hot_key_id_(0),
+      event_tap_(NULL),
+      event_tap_source_(NULL),
+      event_handler_(NULL) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+}
+
+GlobalShortcutListenerMac::~GlobalShortcutListenerMac() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // By this point, UnregisterAccelerator should have been called for all
+  // keyboard shortcuts. Still we should clean up.
+  if (is_listening_)
+    StopListening();
+
+  // If media keys are still registered, make sure we stop the tap. Again,
+  // This should never happen.

[Mark Mentovai, 2013/12/12 19:51:20]

(nit) lowercase T, since you’re continuing the sentence.

[smus, 2013/12/12 21:13:52]

Done.

+  if (IsAnyMediaKeyRegistered())

[Mark Mentovai, 2013/12/12 19:51:20]

If you’re going to go to the trouble of stopping listening for media keys in
this never-should-happen case, you should do the same for hot keys.

[smus, 2013/12/12 21:13:52]

Done.

+    StopWatchingMediaKeys();
+}
+
+void GlobalShortcutListenerMac::StartListening() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  DCHECK(!accelerator_ids_.empty());
+  DCHECK(!id_accelerators_.empty());
+  DCHECK(!is_listening_);
+
+  is_listening_ = true;
+}
+
+void GlobalShortcutListenerMac::StopListening() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  DCHECK(accelerator_ids_.empty());  // Make sure the set is clean.
+  DCHECK(id_accelerators_.empty());
+  DCHECK(is_listening_);
+
+  is_listening_ = false;
+}
+
+void GlobalShortcutListenerMac::OnHotKeyEvent(EventHotKeyID hot_key_id) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // This hot key should be registered.
+  DCHECK(id_accelerators_.find(hot_key_id.id) != id_accelerators_.end());
+  // Look up the accelerator based on this hot key ID.
+  const ui::Accelerator& accelerator = id_accelerators_[hot_key_id.id];
+  NotifyKeyPressed(accelerator);
+}
+
+bool GlobalShortcutListenerMac::OnMediaKeyEvent(int media_key_code) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  ui::KeyboardCode key_code = MediaKeyCodeToKeyboardCode(media_key_code);
+  // Create an accelerator corresponding to the keyCode.
+  ui::Accelerator accelerator(key_code, 0);
+  // Look for a match with a bound hot_key.
+  if (accelerator_ids_.find(accelerator) != accelerator_ids_.end()) {
+    // If matched, callback to the event handling system.
+    NotifyKeyPressed(accelerator);
+    return true;
+  }
+  return false;
+}
+
+void GlobalShortcutListenerMac::RegisterAccelerator(

[Mark Mentovai, 2013/12/12 20:04:50]

Can you add

CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

to this and UnregisterAccelerator? Since they’re public entry points to here,
you want to make sure that nobody calls them from the wrong thread, since this
class is not thread-safe.

[smus, 2013/12/12 21:13:52]

Done.

+    const ui::Accelerator& accelerator,
+    GlobalShortcutListener::Observer* observer) {
+  if (accelerator_ids_.find(accelerator) != accelerator_ids_.end()) {
+    // The shortcut has already been registered. Some shortcuts, such as
+    // MediaKeys can have multiple targets, all keyed off of the same
+    // accelerator.
+    return;
+  }
+
+  if (CommandService::IsMediaKey(accelerator)) {
+    if (!IsAnyMediaKeyRegistered()) {
+      // If this is the first media key registered, start the event tap.
+      StartWatchingMediaKeys();
+    }
+  } else {
+    // Register hot_key if they are non-media keyboard shortcuts.
+    RegisterHotKey(accelerator, hot_key_id_);
+    if (!IsAnyHotKeyRegistered()) {
+      StartWatchingHotKeys();
+    }
+  }
+
+  // Store the hotkey-ID mappings we will need for lookup later.
+  id_accelerators_[hot_key_id_] = accelerator;
+  accelerator_ids_[accelerator] = hot_key_id_;
+  ++hot_key_id_;
+  GlobalShortcutListener::RegisterAccelerator(accelerator, observer);
+}
+
+void GlobalShortcutListenerMac::UnregisterAccelerator(
+    const ui::Accelerator& accelerator,
+    GlobalShortcutListener::Observer* observer) {
+  // Ensure this accelerator is registered.

[Mark Mentovai, 2013/12/11 22:59:57]

The Windows implementation has an entirely different approach:

  // We may get asked to unregister something that we couldn't register (for
  // example if the shortcut was already taken by another app), so we
  // need to handle that gracefully.
  HotkeyIdMap::iterator it = hotkey_ids_.find(accelerator);
  if (it == hotkey_ids_.end())
    return;

The X11 implementation is the same, but without the comment.

[smus, 2013/12/12 21:13:52]

Done.

+  DCHECK(accelerator_ids_.find(accelerator) != accelerator_ids_.end());

[Mark Mentovai, 2013/12/12 19:51:20]

If the goal of this CL is to achieve parity with existing platform
implementations, even where their behaviors are weird, you should fix this.

[smus, 2013/12/12 21:13:52]

Ok, switched to use the same approach as on other platforms.

+
+  // Unregister the hot_key if it's a keyboard shortcut.
+  if (!CommandService::IsMediaKey(accelerator))
+    UnregisterHotKey(accelerator);
+
+  // Remove hot_key from the mappings.
+  KeyId id = accelerator_ids_[accelerator];

[Mark Mentovai, 2013/12/12 19:51:20]

Avoid naming a variable id in an Objective-C file (this is) because that’s an
Objective-C type name. Call this one key_id.

[smus, 2013/12/12 21:13:52]

Done.

+  id_accelerators_.erase(id);
+  accelerator_ids_.erase(accelerator);
+  GlobalShortcutListener::UnregisterAccelerator(accelerator, observer);
+
+  if (CommandService::IsMediaKey(accelerator)) {
+    // If we unregistered a media key, and now no media keys are registered,
+    // stop the media key tap.
+    if (!IsAnyMediaKeyRegistered())
+      StopWatchingMediaKeys();
+  } else {
+    // If we unregistered a hot key, and no more hot keys are registered, remove
+    // the hot key handler.
+    if (!IsAnyHotKeyRegistered() && event_handler_) {

[Robert Sesek, 2013/12/12 20:33:10]

Why the |&& event_handler_| check here?

[smus, 2013/12/12 21:13:52]

Fair point, this should never happen (which is captured by the DCHECK in
StopWatchingHotKeys)

+      StopWatchingHotKeys();
+    }
+  }
+

[Mark Mentovai, 2013/12/12 20:04:50]

(nit) Extra blank line.

[smus, 2013/12/12 21:13:52]

Done.

+}
+
+void GlobalShortcutListenerMac::RegisterHotKey(
+    const ui::Accelerator& accelerator, KeyId hot_key_id) {
+  EventHotKeyID event_hot_key_id;
+
+  // Signature uniquely identifies the application that owns this hot_key.
+  event_hot_key_id.signature = base::mac::CreatorCodeForApplication();
+  event_hot_key_id.id = hot_key_id;
+
+  // Translate ui::Accelerator modifiers to cmdKey, altKey, etc.
+  int modifiers = 0;
+  modifiers |= (accelerator.IsShiftDown() ? shiftKey : 0);
+  modifiers |= (accelerator.IsCtrlDown() ? controlKey : 0);
+  modifiers |= (accelerator.IsAltDown() ? optionKey : 0);
+  modifiers |= (accelerator.IsCmdDown() ? cmdKey : 0);
+
+  int key_code = ui::MacKeyCodeForWindowsKeyCode(accelerator.key_code(), 0,
+      NULL, NULL);
+
+  // Register the event hot key.
+  EventHotKeyRef hot_key_ref;
+  RegisterEventHotKey(key_code, modifiers, event_hot_key_id,
+      GetApplicationEventTarget(), 0, &hot_key_ref);
+
+  id_hot_key_refs_[hot_key_id] = hot_key_ref;
+}
+
+void GlobalShortcutListenerMac::UnregisterHotKey(
+    const ui::Accelerator& accelerator) {
+  // Ensure this accelerator is already registered.
+  DCHECK(accelerator_ids_.find(accelerator) != accelerator_ids_.end());
+  // Get the ref corresponding to this accelerator.
+  KeyId id = accelerator_ids_[accelerator];

[Mark Mentovai, 2013/12/12 19:51:20]

Same thing here.

[smus, 2013/12/12 21:13:52]

Done.

+  EventHotKeyRef ref = id_hot_key_refs_[id];
+  // Unregister the event hot key.
+  UnregisterEventHotKey(ref);
+
+  // Remove the event from the mapping.
+  id_hot_key_refs_.erase(id);
+}
+
+void GlobalShortcutListenerMac::StartWatchingMediaKeys() {
+  // Make sure there's no existing event tap.
+  DCHECK(event_tap_ == NULL);
+  DCHECK(event_tap_source_ == NULL);
+
+  // Add an event tap to intercept the system defined media key events.
+  event_tap_ = CGEventTapCreate(kCGSessionEventTap,
+      kCGHeadInsertEventTap,
+      kCGEventTapOptionDefault,
+      CGEventMaskBit(NX_SYSDEFINED),
+      EventTapCallback,
+      this);
+  if (event_tap_ == NULL) {
+    LOG(ERROR) << "Error: failed to create event tap.";
+    return;
+  }
+
+  event_tap_source_ = CFMachPortCreateRunLoopSource(kCFAllocatorSystemDefault,
+      event_tap_, 0);
+  if (event_tap_source_ == NULL) {
+    LOG(ERROR) << "Error: failed to create new run loop source.";
+    return;
+  }
+
+  CFRunLoopAddSource(CFRunLoopGetCurrent(), event_tap_source_,
+      kCFRunLoopCommonModes);
+}
+
+void GlobalShortcutListenerMac::StopWatchingMediaKeys() {
+  CFRunLoopRemoveSource(CFRunLoopGetCurrent(), event_tap_source_,
+      kCFRunLoopCommonModes);
+  // Ensure both event tap and source are initialized.
+  DCHECK(event_tap_ != NULL);
+  DCHECK(event_tap_source_ != NULL);
+
+  // Invalidate the event tap.
+  CFMachPortInvalidate(event_tap_);
+  CFRelease(event_tap_);
+  event_tap_ = NULL;
+
+  // Release the event tap source.
+  CFRelease(event_tap_source_);
+  event_tap_source_ = NULL;
+}
+
+void GlobalShortcutListenerMac::StartWatchingHotKeys() {
+  DCHECK(!event_handler_);
+  EventHandlerUPP hot_key_function = NewEventHandlerUPP(HotKeyHandler);
+  EventTypeSpec event_type;
+  event_type.eventClass = kEventClassKeyboard;
+  event_type.eventKind = kEventHotKeyPressed;
+  InstallApplicationEventHandler(
+      hot_key_function, 1, &event_type, this, &event_handler_);
+}
+
+void GlobalShortcutListenerMac::StopWatchingHotKeys() {
+  DCHECK(event_handler_);
+  RemoveEventHandler(event_handler_);
+  event_handler_ = NULL;
+}
+
+bool GlobalShortcutListenerMac::IsAnyMediaKeyRegistered() {
+  // Iterate through registered accelerators, looking for media keys.
+  AcceleratorIdMap::iterator it;
+  for (it = accelerator_ids_.begin(); it != accelerator_ids_.end(); ++it) {
+    if (CommandService::IsMediaKey(it->first))
+      return true;
+  }
+  return false;
+}
+
+bool GlobalShortcutListenerMac::IsAnyHotKeyRegistered() {
+  AcceleratorIdMap::iterator it;
+  for (it = accelerator_ids_.begin(); it != accelerator_ids_.end(); ++it) {
+    if (!CommandService::IsMediaKey(it->first))
+      return true;
+  }
+  return false;
+}
+
+// Processed events should propagate if they aren't handled by any listeners.
+// For events that don't matter, this handler should return as quickly as
+// possible.
+// Returning event causes the event to propagate to other applications.
+// Returning NULL prevents the event from propagating.
+// static
+CGEventRef GlobalShortcutListenerMac::EventTapCallback(
+    CGEventTapProxy proxy, CGEventType type, CGEventRef event, void* refcon) {
+  GlobalShortcutListenerMac* shortcut_listener =
+      static_cast<GlobalShortcutListenerMac*>(refcon);
+
+  // Handle the timeout case by re-enabling the tap.
+  if (type == kCGEventTapDisabledByTimeout) {
+    CGEventTapEnable(shortcut_listener->event_tap_, TRUE);
+    return event;
+  }
+
+  // Convert the CGEvent to an NSEvent for access to the data1 field.
+  NSEvent* ns_event = [NSEvent eventWithCGEvent:event];
+  if (ns_event == nil) {
+    return event;
+  }
+
+  // Ignore events that are not system defined media keys.
+  if (type != NX_SYSDEFINED ||
+      [ns_event type] != NSSystemDefined ||
+      [ns_event subtype] != kSystemDefinedEventMediaKeysSubtype) {
+    return event;
+  }
+
+  NSInteger data1 = [ns_event data1];
+  // Ignore media keys that aren't previous, next and play/pause.
+  // Magical constants are from http://weblog.rogueamoeba.com/2007/09/29/
+  int key_code = (data1 & 0xFFFF0000) >> 16;
+  if (key_code != NX_KEYTYPE_PLAY && key_code != NX_KEYTYPE_NEXT &&
+      key_code != NX_KEYTYPE_PREVIOUS && key_code != NX_KEYTYPE_FAST &&
+      key_code != NX_KEYTYPE_REWIND) {
+    return event;
+  }
+
+  int key_flags = data1 & 0x0000FFFF;
+  bool is_key_pressed = ((key_flags & 0xFF00) >> 8) == 0xA;
+
+  // If the key wasn't pressed (eg. was released), ignore this event.
+  if (!is_key_pressed)
+    return event;
+
+  // Now we have a media key that we care about. Send it to the caller.
+  bool was_handled = shortcut_listener->OnMediaKeyEvent(key_code);
+
+  // Prevent event from proagating to other apps if handled by Chrome.
+  if (was_handled)
+    return NULL;
+
+  // By default, pass the event through.
+  return event;
+}
+
+// static
+OSStatus GlobalShortcutListenerMac::HotKeyHandler(
+    EventHandlerCallRef next_handler, EventRef event, void* user_data) {
+  // Extract the hotkey from the event.
+  EventHotKeyID hot_key_id;
+  OSStatus result = GetEventParameter(event, kEventParamDirectObject,
+      typeEventHotKeyID, NULL, sizeof(hot_key_id), NULL, &hot_key_id);
+  if (result != noErr)
+    return result;
+
+  GlobalShortcutListenerMac* shortcut_listener =
+      static_cast<GlobalShortcutListenerMac*>(user_data);
+  shortcut_listener->OnHotKeyEvent(hot_key_id);
+  return noErr;
+}
+

[Mark Mentovai, 2013/12/12 19:51:20]

(nit) Extra blank line.

[smus, 2013/12/12 21:13:52]

Done.

+
+}  // namespace extensions