Flycut/SGHotKeysLib/SGHotKeyCenter.m

//
//  SGHotKeyCenter.m
//  SGHotKeyCenter
//
//  Created by Justin Williams on 7/26/09.
//  Copyright 2009 Second Gear. All rights reserved.
//

#import <Carbon/Carbon.h>
#import "SGHotKeyCenter.h"
#import "SGHotKey.h"
#import "SGKeyCombo.h"

OSType const kHotKeySignature = 'SGHk';

@interface SGHotKeyCenter ()
- (SGHotKey *)_hotKeyForCarbonHotKey:(EventHotKeyRef)carbonHotKey;
- (EventHotKeyRef)_carbonHotKeyForHotKey:(SGHotKey *)hotKey;

- (void)_updateEventHandler;
- (void)_hotKeyDown: (SGHotKey *)hotKey;
- (void)_hotKeyUp: (SGHotKey *)hotKey;
static OSStatus hotKeyEventHandler(EventHandlerCallRef inHandlerRef, EventRef inEvent, void* refCon );
@end


static SGHotKeyCenter *sharedCenter = nil;

@implementation SGHotKeyCenter

+ (void)initialize {
	if (!sharedCenter) {
		sharedCenter = [[self alloc] init];
	}	
}

- (void)dealloc {
  [hotKeys release];
  [super dealloc];
}

+ (SGHotKeyCenter *)sharedCenter {    
  return sharedCenter;
}

+ (id) allocWithZone:(NSZone *)zone {
  //Usually already set by +initialize.
  if (sharedCenter) {
    //The caller expects to receive a new object, so implicitly retain it to balance out the caller's eventual release message.
    return [sharedCenter retain];
  } else {
    //When not already set, +initialize is our caller—it's creating the shared instance. Let this go through.
    return [super allocWithZone:zone];
  }
}

- (id) init {
  if (!hasInited) {
    if ((self = [super init])) {
      //Initialize the instance here.
			hotKeys = [[NSMutableDictionary alloc] init];    
      hasInited = YES;
    }
  }
	
  return self;
}

- (BOOL)registerHotKey:(SGHotKey *)theHotKey {
  OSStatus error;
  EventHotKeyID hotKeyID;
  EventHotKeyRef carbonHotKey;
  NSValue *key = nil;
  
  if ([[self allHotKeys] containsObject:theHotKey])
    [self unregisterHotKey:theHotKey];
  
  if (![[theHotKey keyCombo] isValidHotKeyCombo])
    return YES;
  
  static UInt32 currentId = 0;
  hotKeyID.signature = kHotKeySignature;
  hotKeyID.id = ++currentId;
  
  theHotKey.hotKeyID = hotKeyID;
  
  error = RegisterEventHotKey(theHotKey.keyCombo.keyCode,
                              theHotKey.keyCombo.modifiers,
                              hotKeyID,
                              GetEventDispatcherTarget(),
                              0,
                              &carbonHotKey);
  
  if (error) 
    return NO;
  
  key = [NSValue valueWithPointer:carbonHotKey];
  
  if (theHotKey && key)
    [hotKeys setObject:theHotKey forKey:key];
  
  [self _updateEventHandler];
  
  return YES;
}


- (void)unregisterHotKey:(SGHotKey *)theHotKey {
  EventHotKeyRef carbonHotKey;
  NSValue *key = nil;
  
  if (![[self allHotKeys] containsObject:theHotKey])
		return;
	
	carbonHotKey = [self _carbonHotKeyForHotKey:theHotKey];
	NSAssert(carbonHotKey != nil, @"");
  
	UnregisterEventHotKey(carbonHotKey);
  
	key = [NSValue valueWithPointer:carbonHotKey];
	[hotKeys removeObjectForKey:key];
	
	[self _updateEventHandler];
}

- (NSArray *)allHotKeys {
  return [hotKeys allValues];
}


- (SGHotKey *)hotKeyWithIdentifier:(id)theIdentifier {
  if (!theIdentifier)
    return nil;
  
  for (SGHotKey *hotKey in [self allHotKeys]) {
    if([[hotKey identifier] isEqual:theIdentifier] )
			return hotKey;
  }
  
  return nil;
}

- (OSStatus)sendCarbonEvent:(EventRef)event {
  OSStatus error;
  EventHotKeyID hotKeyID;
  SGHotKey *hotKey = nil;

  NSAssert(GetEventClass(event) == kEventClassKeyboard, @"Unknown event class");

  error = GetEventParameter(event,
                            kEventParamDirectObject, 
                            typeEventHotKeyID,
                            nil,
                            sizeof(EventHotKeyID),
                            nil,
                            &hotKeyID);
  if (error)
    return error;

  NSAssert(hotKeyID.signature == kHotKeySignature, @"Invalid hot key id");
  NSAssert(hotKeyID.id != 0, @"Invalid hot key id");

  for (SGHotKey *thisHotKey in [self allHotKeys]) {
    if ([thisHotKey matchesHotKeyID:hotKeyID]) {
      hotKey = thisHotKey;
      break;
    }
  }
 
  switch (GetEventKind(event)) {
    case kEventHotKeyPressed:
      [self _hotKeyDown:hotKey];
      break;

    case kEventHotKeyReleased:
      [self _hotKeyUp:hotKey];
      break;
      
    default:
      NSAssert(0, @"Unknown event kind");
      break;
  }

  return noErr;
}

- (SGHotKey *)_hotKeyForCarbonHotKey:(EventHotKeyRef)carbonHotKey {
  NSValue *key = [NSValue valueWithPointer:carbonHotKey];
	return [hotKeys objectForKey:key];
}

- (EventHotKeyRef)_carbonHotKeyForHotKey:(SGHotKey *)hotKey {
  NSArray *values;
  NSValue *value;

  values = [hotKeys allKeysForObject:hotKey];
  NSAssert([values count] == 1, @"Failed to find Carbon Hotkey for SGHotKey");

  value = [values lastObject];

  return (EventHotKeyRef)[value pointerValue];
}

- (void)_updateEventHandler {  
	if ([hotKeys count] && eventHandlerInstalled == NO) {
		EventTypeSpec eventSpec[2] = {
			{ kEventClassKeyboard, kEventHotKeyPressed },
			{ kEventClassKeyboard, kEventHotKeyReleased }
		};
    
		InstallEventHandler(GetEventDispatcherTarget(), 
                        (EventHandlerProcPtr)hotKeyEventHandler, 
                        2, eventSpec, nil, nil);
    
		eventHandlerInstalled = YES;
	}  
}

- (void)_hotKeyDown:(SGHotKey *)hotKey {
  [hotKey invoke];
}

- (void)_hotKeyUp:(SGHotKey *)hotKey {
  // Nothing!
}

static OSStatus hotKeyEventHandler(EventHandlerCallRef theHandlerRef, EventRef theEvent, void *userData ) {
  return [[SGHotKeyCenter sharedCenter] sendCarbonEvent:theEvent];
}
@end