DDHotKeyCenter.m

/*
 DDHotKey -- DDHotKeyCenter.m
 
 Copyright (c) 2010, Dave DeLong <http://www.davedelong.com>
 
 Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
 
 The software is  provided "as is", without warranty of any kind, including all implied warranties of merchantability and fitness. In no event shall the author(s) or copyright holder(s) be liable for any claim, damages, or other liability, whether in an action of contract, tort, or otherwise, arising from, out of, or in connection with the software or the use or other dealings in the software.
 */

#import "DDHotKeyCenter.h"
#import <Carbon/Carbon.h>

#pragma mark Private Global Declarations

static NSMutableSet * _registeredHotKeys = nil;
static UInt32 _nextHotKeyID = 1;
OSStatus dd_hotKeyHandler(EventHandlerCallRef nextHandler, EventRef theEvent, void * userData);
NSUInteger dd_translateModifierFlags(NSUInteger flags);

#pragma mark DDHotKey

@interface DDHotKey : NSObject {
    id target;
    SEL action;
    id object;
    
#if BUILD_FOR_SNOWLEOPARD
    DDHotKeyTask task;
#endif
    
    unsigned short keyCode;
    NSUInteger modifierFlags;
    UInt32 hotKeyID;
    NSValue * hotKeyRef;
}

@property (retain) id target;
@property SEL action;
@property (retain) id object;
#if BUILD_FOR_SNOWLEOPARD
@property (copy) DDHotKeyTask task;
#endif
@property unsigned short keyCode;
@property NSUInteger modifierFlags;
@property UInt32 hotKeyID;
@property (retain) NSValue * hotKeyRef;

- (void) invokeWithEvent:(NSEvent *)event;
- (BOOL) registerHotKey;
- (void) unregisterHotKey;

@end

@implementation DDHotKey

@synthesize target, action, object, task, keyCode, modifierFlags, hotKeyID, hotKeyRef;

- (void) invokeWithEvent:(NSEvent *)event {
    if (target != nil && action != nil && [target respondsToSelector:action]) {
        [target performSelector:action withObject:event withObject:object];
    }
#if BUILD_FOR_SNOWLEOPARD
    else if (task != nil) {
        task(event);
    }
#endif
}

- (NSString *) actionString {
    return NSStringFromSelector(action);
}

- (BOOL) registerHotKey {
    EventHotKeyID keyID;
    keyID.signature = 'htk1';
    keyID.id = _nextHotKeyID;
    
    EventHotKeyRef carbonHotKey;
    OSStatus err = RegisterEventHotKey(keyCode, modifierFlags, keyID, GetEventDispatcherTarget(), 0, &carbonHotKey);
    
    //error registering hot key
    if (err != 0) { return NO; }
    
    NSValue * refValue = [NSValue valueWithPointer:carbonHotKey];
    [self setHotKeyRef:refValue];
    [self setHotKeyID:_nextHotKeyID];
    
    _nextHotKeyID++;
    
    return YES;
}

- (void) unregisterHotKey {
    EventHotKeyRef carbonHotKey = (EventHotKeyRef)[hotKeyRef pointerValue];
    UnregisterEventHotKey(carbonHotKey);
    [self setHotKeyRef:nil];
}

- (void) dealloc {
    [target release], target = nil;
    [object release], object = nil;
    if (hotKeyRef != nil) {
        [self unregisterHotKey];
        [hotKeyRef release], hotKeyRef = nil;
    }
    [super dealloc];
}

@end

#pragma mark DDHotKeyCenter

@implementation DDHotKeyCenter

+ (void) initialize {
    if (_registeredHotKeys == nil) {
        _registeredHotKeys = [[NSMutableSet alloc] init];
        _nextHotKeyID = 1;
        EventTypeSpec eventSpec;
        eventSpec.eventClass = kEventClassKeyboard;
        eventSpec.eventKind = kEventHotKeyReleased;
        InstallApplicationEventHandler(&dd_hotKeyHandler, 1, &eventSpec, NULL, NULL);
    }
}

- (NSSet *) hotKeysMatchingPredicate:(NSPredicate *)predicate {
    return [_registeredHotKeys filteredSetUsingPredicate:predicate];
}

- (BOOL) hasRegisteredHotKeyWithKeyCode:(unsigned short)keyCode modifierFlags:(NSUInteger)flags {
    NSPredicate * predicate = [NSPredicate predicateWithFormat:@"keyCode = %hu AND modifierFlags = %lu", keyCode, dd_translateModifierFlags(flags)];
    return ([[self hotKeysMatchingPredicate:predicate] count] > 0);
}

#if BUILD_FOR_SNOWLEOPARD
- (BOOL) registerHotKeyWithKeyCode:(unsigned short)keyCode modifierFlags:(NSUInteger)flags task:(DDHotKeyTask)task {
    //we can't add a new hotkey if something already has this combo
    if ([self hasRegisteredHotKeyWithKeyCode:keyCode modifierFlags:flags]) { return NO; }
    
    //translate the flags
    NSUInteger modifierFlags = dd_translateModifierFlags(flags);
    
    DDHotKey * newHotKey = [[DDHotKey alloc] init];
    [newHotKey setTask:task];
    [newHotKey setKeyCode:keyCode];
    [newHotKey setModifierFlags:modifierFlags];
    
    BOOL success = [newHotKey registerHotKey];
    if (success) {
        [_registeredHotKeys addObject:newHotKey];
    }
    
    [newHotKey release];
    return success;
}
#endif

- (BOOL) registerHotKeyWithKeyCode:(unsigned short)keyCode modifierFlags:(NSUInteger)flags target:(id)target action:(SEL)action object:(id)object {
    //we can't add a new hotkey if something already has this combo
    if ([self hasRegisteredHotKeyWithKeyCode:keyCode modifierFlags:flags]) { return NO; }
    
    //translate the flags
    NSUInteger modifierFlags = dd_translateModifierFlags(flags);
    
    //build the hotkey object:
    DDHotKey * newHotKey = [[DDHotKey alloc] init];
    [newHotKey setTarget:target];
    [newHotKey setAction:action];
    [newHotKey setObject:object];
    [newHotKey setKeyCode:keyCode];
    [newHotKey setModifierFlags:modifierFlags];
    
    BOOL success = [newHotKey registerHotKey];
    if (success) {
        [_registeredHotKeys addObject:newHotKey];
    }
    
    [newHotKey release];
    return success;
}

- (void) unregisterHotKeysMatchingPredicate:(NSPredicate *)predicate {
    //explicitly unregister the hotkey, since relying on the unregistration in -dealloc can be problematic
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSSet * matches = [self hotKeysMatchingPredicate:predicate];
    [_registeredHotKeys minusSet:matches];
    for (DDHotKey * key in matches) {
        [key unregisterHotKey];
    }
    [pool release];
}

- (void) unregisterHotKeysWithTarget:(id)target {
    NSPredicate * predicate = [NSPredicate predicateWithFormat:@"target = %@", target];
    [self unregisterHotKeysMatchingPredicate:predicate];
}

- (void) unregisterHotKeysWithTarget:(id)target action:(SEL)action {
    NSPredicate * predicate = [NSPredicate predicateWithFormat:@"target = %@ AND actionString = %@", target, NSStringFromSelector(action)];
    [self unregisterHotKeysMatchingPredicate:predicate];
}

- (void) unregisterHotKeyWithKeyCode:(unsigned short)keyCode modifierFlags:(NSUInteger)flags {
    NSPredicate * predicate = [NSPredicate predicateWithFormat:@"keyCode = %hu AND modifierFlags = %lu", keyCode, dd_translateModifierFlags(flags)];
    [self unregisterHotKeysMatchingPredicate:predicate];
}

@end

OSStatus dd_hotKeyHandler(EventHandlerCallRef nextHandler, EventRef theEvent, void * userData) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    
    EventHotKeyID hotKeyID;
    GetEventParameter(theEvent, kEventParamDirectObject, typeEventHotKeyID, NULL, sizeof(hotKeyID),NULL,&hotKeyID);
    
    UInt32 keyID = hotKeyID.id;
    
    NSSet * matchingHotKeys = [_registeredHotKeys filteredSetUsingPredicate:[NSPredicate predicateWithFormat:@"hotKeyID = %u", keyID]];
    if ([matchingHotKeys count] > 1) { NSLog(@"ERROR!"); }
    DDHotKey * matchingHotKey = [matchingHotKeys anyObject];
    
    NSEvent * event = [NSEvent eventWithEventRef:theEvent];
    NSEvent * keyEvent = [NSEvent keyEventWithType:NSKeyUp 
                                          location:[event locationInWindow] 
                                     modifierFlags:[event modifierFlags]
                                         timestamp:[event timestamp] 
                                      windowNumber:-1 
                                           context:nil 
                                        characters:@"" 
                       charactersIgnoringModifiers:@"" 
                                         isARepeat:NO 
                                           keyCode:[matchingHotKey keyCode]];

    [matchingHotKey invokeWithEvent:keyEvent];
    
    [pool release];
    
    return noErr;
}

NSUInteger dd_translateModifierFlags(NSUInteger flags) {
    NSUInteger newFlags = 0;
    if ((flags & NSControlKeyMask) > 0) { newFlags |= controlKey; }
    if ((flags & NSCommandKeyMask) > 0) { newFlags |= cmdKey; }
    if ((flags & NSShiftKeyMask) > 0) { newFlags |= shiftKey; }
    if ((flags & NSAlternateKeyMask) > 0) { newFlags |= optionKey; }
    return newFlags;
}