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"
+
+#import <Cocoa/Cocoa.h>
+
+#include "content/public/browser/browser_thread.h"
+#include "ui/events/event.h"
+#include "ui/base/accelerators/accelerator.h"
+#import "ui/events/keycodes/keyboard_code_conversion_mac.h"
+
+#define SystemDefinedEventMediaKeys 8
+#define EVENT_KEY @"event"
+#define HANDLED_KEY @"handled"
+
+typedef extensions::GlobalShortcutListenerMac GSL;
+
+@interface GlobalShortcutListenerTap : NSObject {
+  @public
+  CFMachPortRef eventTap_;
+
+  @private
+  CFRunLoopSourceRef eventTapSource_;
+  CFRunLoopRef tapThreadRunLoop_;
+  GSL *gsl_;
+}
+
+- (id)initWithGSL:(GSL *)gsl;
+- (void)startWatchingMediaKeys;
+- (void)stopWatchingMediaKeys;
+- (void)handleKeyEvent:(NSEvent *)event;
+- (void)handleMediaKeyEvent:(NSEvent *)event;
+- (BOOL)performEventHandlerOnMainThread:(SEL)selector withEvent:(NSEvent*)event;
+@end
+
+// Processed events should propagate if they aren't handled by any listeners.
+// Returning event causes the event to propagate to other applications.
+// Returning NULL prevents the event from propagating.
+static CGEventRef tapEventCallback(
+    CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {
+  NSAutoreleasePool *pool = [NSAutoreleasePool new];

[Finnur, 2013/11/07 10:33:07]

nit: We prefer Foo* foo over Foo *foo. (multiple occurrences)

[smus, 2013/11/16 00:21:44]

Done.

+
+  GlobalShortcutListenerTap *self = (GlobalShortcutListenerTap*) refcon;
+
+  // Handle the timeout case by re-enabling the tap.
+  if (type == kCGEventTapDisabledByTimeout) {
+    LOG(ERROR) << "Event tap was disabled by a timeout.";
+    CGEventTapEnable(self->eventTap_, TRUE);
+    return event;
+  }
+
+  // TODO(smus): do some error handling since eventWithCGEvent can fail.
+  NSEvent *nsEvent = [NSEvent eventWithCGEvent:event];
+
+  // Handle regular keys.
+  if (type == kCGEventKeyDown) {
+    BOOL wasHandled = [self
+        performEventHandlerOnMainThread:@selector(handleKeyEvent:)
+        withEvent:nsEvent];
+    return (wasHandled ? NULL : event);
+  }
+
+  // Handle media keys only (PlayPause, NextTrack, PreviousTrack).
+  if (type == NX_SYSDEFINED &&
+      [nsEvent subtype] == SystemDefinedEventMediaKeys) {
+    int keyCode = (([nsEvent data1] & 0xFFFF0000) >> 16);
+    if (keyCode == NX_KEYTYPE_PLAY || keyCode == NX_KEYTYPE_NEXT ||
+        keyCode == NX_KEYTYPE_PREVIOUS || keyCode == NX_KEYTYPE_FAST ||
+        keyCode == NX_KEYTYPE_REWIND) {
+      BOOL wasHandled = [self
+          performEventHandlerOnMainThread:@selector(handleMediaKeyEvent:)
+          withEvent:nsEvent];
+      return (wasHandled ? NULL : event);
+    }
+  }
+  [pool drain];
+  // By default, pass the event through.
+  return event;
+}
+
+@implementation GlobalShortcutListenerTap
+
+- (id)initWithGSL:(GSL*)gsl {
+  gsl_ = gsl;
+  return self;
+}
+
+- (void)eventTapThread {
+  tapThreadRunLoop_ = CFRunLoopGetCurrent();
+  CFRunLoopAddSource(tapThreadRunLoop_, eventTapSource_,
+      kCFRunLoopCommonModes);
+  CFRunLoopRun();
+}
+
+- (BOOL)performEventHandlerOnMainThread:(SEL)selector
+      withEvent:(NSEvent*)event {
+  NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
+  [dict setObject:event forKey:EVENT_KEY];
+  [self performSelectorOnMainThread:selector
+      withObject:dict waitUntilDone:YES];
+  // Keep track of the result from the main thread to know if the event has
+  // been handled.
+  BOOL wasHandled = [[dict objectForKey:HANDLED_KEY] boolValue];
+  [dict release];
+  return wasHandled;
+}
+
+- (ui::KeyboardCode)mediaKeyCodeToKeyboardCode:(int)keyCode {
+  switch (keyCode) {
+    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;
+}
+
+- (void)startWatchingMediaKeys {
+  // Prevent having multiple mediaKeys threads

[Finnur, 2013/11/07 10:33:07]

nit: In general, we end all comments in period (namespace annotations and
function static annotations are an exception).

[smus, 2013/11/16 00:21:44]

Done.

+  [self stopWatchingMediaKeys];

[Finnur, 2013/11/07 10:33:07]

Thinking out loud: Doesn't starting twice indicate a logic error in the
implementation? Shouldn't we be asserting in that case?

[smus, 2013/11/16 00:21:44]

Yep, changed to an assertion.

+
+  // Add an event tap to intercept the system defined media key events
+  eventTap_ = CGEventTapCreate(kCGSessionEventTap,
+      kCGHeadInsertEventTap,
+      kCGEventTapOptionDefault,
+      CGEventMaskBit(NX_SYSDEFINED) | CGEventMaskBit(kCGEventKeyDown),
+      tapEventCallback,
+      self);
+  assert(eventTap_ != NULL);
+
+  eventTapSource_ = CFMachPortCreateRunLoopSource(kCFAllocatorSystemDefault,
+      eventTap_, 0);
+  assert(eventTapSource_ != NULL);
+
+  // Run the event tap in separate thread to prevent blocking UI.
+  [NSThread detachNewThreadSelector:@selector(eventTapThread)
+      toTarget:self withObject:nil];
+}
+- (void)stopWatchingMediaKeys {

[Finnur, 2013/11/07 10:33:07]

nit: linebreak

[smus, 2013/11/16 00:21:44]

Done.

+  if (tapThreadRunLoop_) {
+    CFRunLoopStop(tapThreadRunLoop_);
+    tapThreadRunLoop_ = nil;
+  }
+
+  if (eventTap_) {
+    CFMachPortInvalidate(eventTap_);
+    CFRelease(eventTap_);
+    eventTap_ = nil;
+  }
+
+  if (eventTapSource_) {
+    CFRelease(eventTapSource_);
+    eventTapSource_ = nil;
+  }
+}
+
+- (void)handleKeyEvent:(NSMutableDictionary *)dict {
+  NSEvent *event = [dict objectForKey:EVENT_KEY];
+
+  ui::KeyboardCode keyCode = ui::KeyboardCodeFromNSEvent(event);
+  int modifiers = 0;
+  NSUInteger flags = [event modifierFlags];
+  modifiers |= (flags & NSShiftKeyMask) ? ui::EF_SHIFT_DOWN : 0;
+  modifiers |= (flags & NSAlternateKeyMask ) ? ui::EF_ALT_DOWN : 0;
+  modifiers |= (flags & NSControlKeyMask) ? ui::EF_CONTROL_DOWN : 0;
+  modifiers |= (flags & NSCommandKeyMask) ? ui::EF_COMMAND_DOWN : 0;
+
+  bool result = gsl_->OnKeyEvent(keyCode, modifiers);
+  [dict setObject:[NSNumber numberWithBool:result] forKey:HANDLED_KEY];
+}
+
+// Event will have been retained in the other thread.
+- (void)handleMediaKeyEvent:(NSMutableDictionary *)dict {
+  NSEvent *event = [dict objectForKey:EVENT_KEY];
+
+  int keyCode = (([event data1] & 0xFFFF0000) >> 16);
+  int keyFlags = ([event data1] & 0x0000FFFF);
+  BOOL keyIsPressed = (((keyFlags & 0xFF00) >> 8)) == 0xA;
+  //int keyRepeat = (keyFlags & 0x1);

[Finnur, 2013/11/07 10:33:07]

Remove?

[smus, 2013/11/16 00:21:44]

Done.

+
+  bool result = false;
+  if (keyIsPressed) {
+    result = gsl_->OnMediaKeyEvent([self mediaKeyCodeToKeyboardCode:keyCode]);
+  }

[Finnur, 2013/11/07 10:33:07]

nit: When the if clause is single line we omit the braces.

[smus, 2013/11/16 00:21:44]

Not my favorite, but I will comply :)

+  [dict setObject:[NSNumber numberWithBool:result] forKey:HANDLED_KEY];
+}
+
+
+

[Finnur, 2013/11/07 10:33:07]

nit: lots of extra linebreaks.

[smus, 2013/11/16 00:21:44]

Done.

+@end
+
+
+using content::BrowserThread;
+
+namespace {
+
+static base::LazyInstance<extensions::GlobalShortcutListenerMac> instance =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace extensions {
+
+// static
+GlobalShortcutListener* GlobalShortcutListener::GetInstance() {
+  LOG(ERROR) << "GlobalShortcutListener GetInstance";
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  return instance.Pointer();
+}
+
+GlobalShortcutListenerMac::GlobalShortcutListenerMac()
+    : is_listening_(false) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // TODO(implementor): Remove this.
+  LOG(ERROR) << "GlobalShortcutListenerMac object created";
+
+  tap_.reset([[GlobalShortcutListenerTap alloc] initWithGSL:this]);
+}
+
+GlobalShortcutListenerMac::~GlobalShortcutListenerMac() {
+  if (is_listening_)
+    StopListening();
+}
+
+void GlobalShortcutListenerMac::StartListening() {
+  DCHECK(!is_listening_);  // Don't start twice.
+  DCHECK(!registered_hot_keys_.empty());  // Also don't start if no hotkey is
+                                          // registered.
+  LOG(ERROR) << "GlobalShortcutListenerMac StartListening";
+  is_listening_ = true;
+
+  [tap_ startWatchingMediaKeys];
+}
+
+void GlobalShortcutListenerMac::StopListening() {
+  DCHECK(is_listening_);  // No point if we are not already listening.
+  DCHECK(registered_hot_keys_.empty());  // Make sure the set is clean before
+                                         // ending.
+  LOG(ERROR) << "GlobalShortcutListenerMac StopListening";
+  is_listening_ = false;
+
+  [tap_ stopWatchingMediaKeys];
+}
+
+void GlobalShortcutListenerMac::RegisterAccelerator(
+    const ui::Accelerator& accelerator,
+    GlobalShortcutListener::Observer* observer) {
+  LOG(ERROR) << "GlobalShortcutListenerMac RegisterAccelerator";
+  VLOG(0) << "Registered keyCode: " << accelerator.key_code()
+      << ", modifiers: " << accelerator.modifiers();
+  // To implement:
+  // 1) Convert modifiers to platform specific modifiers.
+  // 2) Register for the hotkey.
+  // 3) If not successful, log why.
+  // 4) Else, call base class RegisterAccelerator.
+  registered_hot_keys_.insert(accelerator);
+  GlobalShortcutListener::RegisterAccelerator(accelerator, observer);
+}
+
+void GlobalShortcutListenerMac::UnregisterAccelerator(
+    const ui::Accelerator& accelerator,
+    GlobalShortcutListener::Observer* observer) {
+  LOG(ERROR) << "GlobalShortcutListenerMac UnregisterAccelerator";
+  // To implement:
+  // 1) Unregister for the hotkey.
+  // 2) Call base class UnregisterAccelerator.
+
+  registered_hot_keys_.erase(accelerator);
+  GlobalShortcutListener::UnregisterAccelerator(accelerator, observer);
+}
+
+// Returns true iff event was handled.
+bool GlobalShortcutListenerMac::OnKeyEvent(ui::KeyboardCode keyCode,
+    int modifiers) {
+  VLOG(0) << "OnKeyEvent! keyCode: " << keyCode << ", modifiers: " << modifiers;
+  // Create an accelerator corresponding to the keyCode.
+  ui::Accelerator accelerator(keyCode, modifiers);
+  // Look for a match with a bound hotkey.
+  if (registered_hot_keys_.find(accelerator) != registered_hot_keys_.end()) {
+    // If matched, callback to the event handling system.
+    instance.Get().NotifyKeyPressed(accelerator);
+    return true;
+  }
+  return false;
+}
+
+// Returns true iff event was handled.
+bool GlobalShortcutListenerMac::OnMediaKeyEvent(ui::KeyboardCode keyCode) {
+  VLOG(0) << "OnMediaKeyEvent! keyCode: " << keyCode;
+  // Create an accelerator corresponding to the keyCode.
+  ui::Accelerator accelerator(keyCode, 0);
+  // Look for a match with a bound hotkey.
+  if (registered_hot_keys_.find(accelerator) != registered_hot_keys_.end()) {
+    // If matched, callback to the event handling system.
+    instance.Get().NotifyKeyPressed(accelerator);
+    return true;
+  }
+  return false;
+}
+
+}  // namespace extensions