Calling UIGestureRecognizer from UITouch object - ios

Question

I am trying to associate a Gesture with UITouch object because I need to pass data through a target action Method.
I have something implemented but it is inefficient,it get 100% of the CPU processing, it is probably because it is coded incorrectly.
There is my instance method for the UITouch event which call the UIPangesture
- (BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event
{
return YES;
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc]
initWithTarget:self action:#selector(handlePan:)];
[self addGestureRecognizer: panGesture];
}
There is my instance method for the UIPAnGestureRecognizer
- (IBAction)handlePan:(UIPanGestureRecognizer *)event
{
if (event.numberOfTouches==1)
{
CGPoint lastPoint = [event locationOfTouch: event.numberOfTouches - 1 inView: event.view];
CGRect bounds = self.bounds;
CGPoint center = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds));
CGPoint delta = CGPointMake(lastPoint.x - center.x, lastPoint.y - center.y);
CGFloat angle = (delta.y == 0 ? delta.x >= 0 ? 0 : M_PI : atan2(delta.y, delta.x));
angle = fmod(angle, M_PI * 2.0);
angle += angle >= 0 ? 0 : M_PI * 2.0;
UIColor *color = [UIColor colorWithHue: angle / (M_PI * 2.0) saturation:1. brightness:1. alpha:1];
if ([color getRed: &r green: &g blue:&b alpha: &a]){
rValue = r;
gValue = g;
bValue = b;
[self setNeedsDisplay];
[self sendActionsForControlEvents:UIControlEventValueChanged];
[self updateLabels];
}
}
}
And there there the methods which call the action method to obtain the variables from the color picker
- (void)setup:(CsoundObj *)csoundObj
{
NSLog(#"Color value - R : %f G : %f : B %f", rValue, gValue, bValue);
channelPtrR = [csoundObj getInputChannelPtr:#"mix" channelType:CSOUND_CONTROL_CHANNEL];
channelPtrG = [csoundObj getInputChannelPtr:#"pitch" channelType:CSOUND_CONTROL_CHANNEL];
channelPtrB = [csoundObj getInputChannelPtr:#"c" channelType:CSOUND_CONTROL_CHANNEL];
cachedValueR = rValue;
cachedValueG = gValue;
cachedValueB = bValue;
self.cacheDirty = YES;
[self addTarget:self action:#selector(updateValueCache:) forControlEvents:UIControlEventValueChanged];
}
- (void)updateValueCache:(id)sender
{
cachedValueR = ((CustomView*)sender).rValue;
cachedValueG = ((CustomView*)sender).gValue;
cachedValueB = ((CustomView*)sender).bValue;
self.cacheDirty = YES;
}
- (void)updateValuesToCsound
{
if (self.cacheDirty) {
*channelPtrR = cachedValueR;
*channelPtrG = cachedValueG;
*channelPtrB = cachedValueB;
self.cacheDirty = NO;
}
}
- (void)updateValuesFromCsound
{
}
- (void)cleanup
{
[self removeTarget:self action:#selector(updateValueCache:) forControlEvents:UIControlEventValueChanged];
}
I know the problem it is on the instance method for the UITouch event which call the UIPangesture, any other way to do it more efficiently?

Answer 1

I think that you are calling this section of code way too often:
CGPoint lastPoint = [event locationOfTouch: event.numberOfTouches - 1 inView: event.view];
CGRect bounds = self.bounds;
CGPoint center = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds));
CGPoint delta = CGPointMake(lastPoint.x - center.x, lastPoint.y - center.y);
CGFloat angle = (delta.y == 0 ? delta.x >= 0 ? 0 : M_PI : atan2(delta.y, delta.x));
angle = fmod(angle, M_PI * 2.0);
angle += angle >= 0 ? 0 : M_PI * 2.0;
UIColor *color = [UIColor colorWithHue: angle / (M_PI * 2.0) saturation:1. brightness:1. alpha:1];
if ([color getRed: &r green: &g blue:&b alpha: &a]){
rValue = r;
gValue = g;
bValue = b;
[self setNeedsDisplay];
[self sendActionsForControlEvents:UIControlEventValueChanged];
[self updateLabels];
}
You are likely calling it when there is no change, or little change. There are two things you could do to reduce the number of calls. You can test for a significant change in the angle like this:
//class property
#property (nonatomic, assign) CGFloat lastAngle;
//In your code
CGFloat deltaAngle = fabs(self.lastAngle - angle)
if (deltaAngle > 0.5) { //select whatever delta works best
angle += angle >= 0 ? 0 : M_PI * 2.0;
UIColor *color = [UIColor colorWithHue: angle / (M_PI * 2.0) saturation:1. brightness:1. alpha:1];
if ([color getRed: &r green: &g blue:&b alpha: &a]){
rValue = r;
gValue = g;
bValue = b;
[self sendActionsForControlEvents:UIControlEventValueChanged];
[self updateLabels];
[self setNeedsDisplay];
}
}
Or you can test for time since the last update like this:
//class property
#property (nonatomic, retain) NSDate *lastTime;
//set it when the view loads
self.lastTime = [NSDate date];
//In your code
NSTimeInterval interval = [[NSDate date] timeIntervalSinceDate:lastdate];
self.lastTime = [NSDate date];
if (interval > 0.05) { //select whatever time interval works best
angle += angle >= 0 ? 0 : M_PI * 2.0;
UIColor *color = [UIColor colorWithHue: angle / (M_PI * 2.0) saturation:1. brightness:1. alpha:1];
if ([color getRed: &r green: &g blue:&b alpha: &a]){
rValue = r;
gValue = g;
bValue = b;
[self sendActionsForControlEvents:UIControlEventValueChanged];
[self updateLabels];
[self setNeedsDisplay];
}
}
Also, are you sure you need the [self setNeedsDisplay] ?