1 files changed, 158 insertions, 0 deletions
diff --git a/MASShortcut+Monitoring.m b/MASShortcut+Monitoring.m
new file mode 100644
index 0000000..1460f6b
--- /dev/null
+++ b/MASShortcut+Monitoring.m
@@ -0,0 +1,158 @@
+#import "MASShortcut+Monitoring.h"
+
+NSMutableDictionary *MASRegisteredHotKeys();
+BOOL InstallCommonEventHandler();
+void UninstallEventHandler();
+void InstallHotkeyWithShortcut(MASShortcut *shortcut, UInt32 *outCarbonHotKeyID, EventHotKeyRef *outCarbonHotKey);
+
+#pragma mark -
+
+@interface MASShortcutHotKey : NSObject
+
+@property (nonatomic, readonly) MASShortcut *shortcut;
+@property (nonatomic, readonly, copy) void (^handler)();
+@property (nonatomic, readonly) EventHotKeyRef carbonHotKey;
+@property (nonatomic, readonly) UInt32 carbonHotKeyID;
+
+- (id)initWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler;
+
+@end
+
+#pragma mark -
+
+@implementation MASShortcut (Monitoring)
+
++ (id)addGlobalHotkeyMonitorWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler
+{
+    NSString *monitor = [NSString stringWithFormat:@"%p: %@", shortcut, shortcut.description];
+    MASShortcutHotKey *hotKey = [[MASShortcutHotKey alloc] initWithShortcut:shortcut handler:handler];
+    [MASRegisteredHotKeys() setObject:hotKey forKey:monitor];
+    return monitor;
+}
+
++ (void)removeGlobalHotkeyMonitor:(id)monitor
+{
+    if (monitor == nil) return;
+    NSMutableDictionary *registeredHotKeys = MASRegisteredHotKeys();
+    [registeredHotKeys removeObjectForKey:monitor];
+    if (registeredHotKeys.count == 0) {
+        UninstallEventHandler();
+    }
+}
+
+@end
+
+#pragma mark -
+
+@implementation MASShortcutHotKey
+
+@synthesize carbonHotKeyID = _carbonHotKeyID;
+@synthesize handler = _handler;
+@synthesize shortcut = _shortcut;
+@synthesize carbonHotKey = _carbonHotKey;
+
+#pragma mark -
+
+- (id)initWithShortcut:(MASShortcut *)shortcut handler:(void (^)())handler
+{
+    self = [super init];
+    if (self) {
+        _shortcut = shortcut;
+        _handler = [handler copy];
+        InstallHotkeyWithShortcut(shortcut, &_carbonHotKeyID, &_carbonHotKey);
+    }
+    return self;
+}
+
+- (void)dealloc
+{
+    [self uninstallExisitingHotKey];
+}
+
+- (void)uninstallExisitingHotKey
+{
+    if (_carbonHotKey) {
+        UnregisterEventHotKey(_carbonHotKey);
+        _carbonHotKey = NULL;
+    }
+}
+
+@end
+
+#pragma mark - Carbon magic
+
+NSMutableDictionary *MASRegisteredHotKeys()
+{
+    static NSMutableDictionary *shared = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        shared = [NSMutableDictionary dictionary];
+    });
+    return shared;
+}
+
+#pragma mark -
+
+FourCharCode const kMASShortcutSignature = 'MASS';
+
+void InstallHotkeyWithShortcut(MASShortcut *shortcut, UInt32 *outCarbonHotKeyID, EventHotKeyRef *outCarbonHotKey)
+{
+    if ((shortcut == nil) || !InstallCommonEventHandler()) return;
+
+    static UInt32 sCarbonHotKeyID = 0;
+	EventHotKeyID hotKeyID = { .signature = kMASShortcutSignature, .id = ++ sCarbonHotKeyID };
+    EventHotKeyRef carbonHotKey = NULL;
+    if (RegisterEventHotKey(shortcut.carbonKeyCode, shortcut.carbonFlags, hotKeyID, GetEventDispatcherTarget(), kEventHotKeyExclusive, &carbonHotKey) != noErr) {
+        carbonHotKey = NULL;
+    }
+
+    if (outCarbonHotKeyID) *outCarbonHotKeyID = hotKeyID.id;
+    if (outCarbonHotKey) *outCarbonHotKey = carbonHotKey;
+}
+
+static OSStatus CarbonCallback(EventHandlerCallRef inHandlerCallRef, EventRef inEvent, void *inUserData)
+{
+	if (GetEventClass(inEvent) != kEventClassKeyboard) return noErr;
+
+	EventHotKeyID hotKeyID;
+	OSStatus status = GetEventParameter(inEvent, kEventParamDirectObject, typeEventHotKeyID, NULL, sizeof(hotKeyID), NULL, &hotKeyID);
+	if (status != noErr) return status;
+
+	if (hotKeyID.signature != kMASShortcutSignature) return noErr;
+
+    [MASRegisteredHotKeys() enumerateKeysAndObjectsUsingBlock:^(id key, MASShortcutHotKey *hotKey, BOOL *stop) {
+        if (hotKeyID.id == hotKey.carbonHotKeyID) {
+            if (hotKey.handler) {
+                hotKey.handler();
+            }
+            *stop = YES;
+        }
+    }];
+
+	return noErr;
+}
+
+#pragma mark -
+
+static EventHandlerRef sEventHandler = NULL;
+
+BOOL InstallCommonEventHandler()
+{
+    if (sEventHandler == NULL) {
+        EventTypeSpec hotKeyPressedSpec = { .eventClass = kEventClassKeyboard, .eventKind = kEventHotKeyPressed };
+        OSStatus status = InstallEventHandler(GetEventDispatcherTarget(), CarbonCallback, 1, &hotKeyPressedSpec, NULL, &sEventHandler);
+        if (status != noErr) {
+            sEventHandler = NULL;
+            return NO;
+        }
+    }
+    return YES;
+}
+
+void UninstallEventHandler()
+{
+    if (sEventHandler) {
+        RemoveEventHandler(sEventHandler);
+        sEventHandler = NULL;
+    }
+}