LightTable/DualTouchTracker.m
/* |
Copyright (C) 2017 Apple Inc. All Rights Reserved. |
See LICENSE.txt for this sample’s licensing information |
Abstract: |
The Dual Touch Tracker tracks the changes of two touches on a multi-touch trackpad. Tracking starts when the movement of two concurrent touches exceeds a threshold value. Tracking ends when either a third touch begins, or one of the touches are released, or touches are cancelled. The owning view must route touchesBeganWithEvent:, touchesMovedWithEvent:, touchesEndedWithEvent: and touchesCancelledWithEvent: responder messages to this tracker. |
*/ |
#import "DualTouchTracker.h" |
@interface DualTouchTracker() |
@property BOOL isTracking; |
@property(readwrite) NSPoint initialPoint; |
@property(readwrite) NSUInteger modifiers; |
- (void)releaseTouches; |
@end |
@implementation DualTouchTracker |
- (instancetype)init { |
if (self = [super init]) { |
self.threshold = 1; |
} |
return self; |
} |
- (void)dealloc { |
[self releaseTouches]; |
} |
#pragma mark NSResponder |
- (void)touchesBeganWithEvent:(NSEvent *)event { |
if (!self.isEnabled) return; |
NSSet *touches = [event touchesMatchingPhase:NSTouchPhaseTouching inView:self.view]; |
if (touches.count == 2) { |
self.initialPoint = [self.view convertPoint:event.locationInWindow fromView:nil]; |
NSArray *array = touches.allObjects; |
_initialTouches[0] = array[0]; |
_initialTouches[1] = array[1]; |
_currentTouches[0] = _initialTouches[0]; |
_currentTouches[1] = _initialTouches[1]; |
} else if (touches.count > 2) { |
// More than 2 touches. Only track 2. |
if (self.isTracking) { |
[self cancelTracking]; |
} else { |
[self releaseTouches]; |
} |
} |
} |
- (void)touchesMovedWithEvent:(NSEvent *)event { |
if (!self.isEnabled) return; |
self.modifiers = event.modifierFlags; |
NSSet *touches = [event touchesMatchingPhase:NSTouchPhaseTouching inView:self.view]; |
if (touches.count == 2 && _initialTouches[0]) { |
NSArray *array = touches.allObjects; |
NSTouch *touch; |
touch = array[0]; |
if ([touch.identity isEqual:_initialTouches[0].identity]) { |
_currentTouches[0] = touch; |
} else { |
_currentTouches[1] = touch; |
} |
touch = array[1]; |
if ([touch.identity isEqual:_initialTouches[0].identity]) { |
_currentTouches[0] = touch; |
} else { |
_currentTouches[1] = touch; |
} |
if (!self.isTracking) { |
NSPoint deltaOrigin = self.deltaOrigin; |
NSSize deltaSize = self.deltaSize; |
if (fabs(deltaOrigin.x) > _threshold || fabs(deltaOrigin.y) > _threshold || fabs(deltaSize.width) > _threshold || fabs(deltaSize.height) > _threshold) { |
self.isTracking = YES; |
if (self.beginTrackingAction) [NSApp sendAction:self.beginTrackingAction to:self.view from:self]; |
} |
} else { |
if (self.updateTrackingAction) [NSApp sendAction:self.updateTrackingAction to:self.view from:self]; |
} |
} |
} |
- (void)touchesEndedWithEvent:(NSEvent *)event { |
if (!self.isEnabled) return; |
self.modifiers = event.modifierFlags; |
[self cancelTracking]; |
} |
- (void)touchesCancelledWithEvent:(NSEvent *)event { |
[self cancelTracking]; |
} |
#pragma mark InputTracker |
- (void)cancelTracking { |
if (self.isTracking) { |
if (self.endTrackingAction) [NSApp sendAction:self.endTrackingAction to:self.view from:self]; |
self.isTracking = NO; |
[self releaseTouches]; |
} |
} |
#pragma mark API |
@synthesize userInfo = _userInfo; |
@synthesize threshold = _threshold; |
@synthesize isTracking = _tracking; |
@synthesize initialPoint = _initialPoint; |
@synthesize beginTrackingAction = _beginTrackingAction; |
@synthesize updateTrackingAction = _updateTrackingAction; |
@synthesize endTrackingAction = _endTrackingAction; |
@synthesize modifiers = _modifiers; |
- (NSPoint)deltaOrigin { |
if (!(_initialTouches[0] && _initialTouches[1] && _currentTouches[0] && _currentTouches[1])) return NSZeroPoint; |
CGFloat x1 = MIN(_initialTouches[0].normalizedPosition.x, _initialTouches[1].normalizedPosition.x); |
CGFloat x2 = MIN(_currentTouches[0].normalizedPosition.x, _currentTouches[1].normalizedPosition.x); |
CGFloat y1 = MIN(_initialTouches[0].normalizedPosition.y, _initialTouches[1].normalizedPosition.y); |
CGFloat y2 = MIN(_currentTouches[0].normalizedPosition.y, _currentTouches[1].normalizedPosition.y); |
NSSize deviceSize = _initialTouches[0].deviceSize; |
NSPoint delta; |
delta.x = (x2 - x1) * deviceSize.width; |
delta.y = (y2 - y1) * deviceSize.height; |
return delta; |
} |
- (NSSize)deltaSize { |
if (!(_initialTouches[0] && _initialTouches[1] && _currentTouches[0] && _currentTouches[1])) return NSZeroSize; |
CGFloat x1,x2,y1,y2,width1,width2,height1,height2; |
x1 = MIN(_initialTouches[0].normalizedPosition.x, _initialTouches[1].normalizedPosition.x); |
x2 = MAX(_initialTouches[0].normalizedPosition.x, _initialTouches[1].normalizedPosition.x); |
width1 = x2 - x1; |
y1 = MIN(_initialTouches[0].normalizedPosition.y, _initialTouches[1].normalizedPosition.y); |
y2 = MAX(_initialTouches[0].normalizedPosition.y, _initialTouches[1].normalizedPosition.y); |
height1 = y2 - y1; |
x1 = MIN(_currentTouches[0].normalizedPosition.x, _currentTouches[1].normalizedPosition.x); |
x2 = MAX(_currentTouches[0].normalizedPosition.x, _currentTouches[1].normalizedPosition.x); |
width2 = x2 - x1; |
y1 = MIN(_currentTouches[0].normalizedPosition.y, _currentTouches[1].normalizedPosition.y); |
y2 = MAX(_currentTouches[0].normalizedPosition.y, _currentTouches[1].normalizedPosition.y); |
height2 = y2 - y1; |
NSSize deviceSize = _initialTouches[0].deviceSize; |
NSSize delta; |
delta.width = (width2 - width1) * deviceSize.width; |
delta.height = (height2 - height1) * deviceSize.height; |
return delta; |
} |
- (void)releaseTouches { |
_initialTouches[0] = nil; |
_initialTouches[1] = nil; |
_currentTouches[0] = nil; |
_currentTouches[1] = nil; |
} |
@end |
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