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Deceleration support for radar/pie charts also
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@danielgindi
danielgindi committed Apr 30, 2015
1 parent 20a146e commit 146bf0b
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Showing 2 changed files with 133 additions and 12 deletions.
5 changes: 5 additions & 0 deletions Charts/Classes/Charts/BarLineChartViewBase.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,11 @@ public class BarLineChartViewBase: ChartViewBase, UIGestureRecognizerDelegate
super.init(coder: aDecoder);
}

deinit
{
stopDeceleration();
}

internal override func initialize()
{
super.initialize();
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140 changes: 128 additions & 12 deletions Charts/Classes/Charts/PieRadarChartViewBase.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,12 @@ public class PieRadarChartViewBase: ChartViewBase
/// flag that indicates if rotation is enabled or not
public var rotationEnabled = true

/// If set to true, chart continues to scroll after touch up
public var dragDecelarationEnabled = true

/// Decelaration friction coefficient in [0 ; 1] interval, higher values indicate that speed will decrease slowly, for example if it set to 0, it will stop immediately, if set to 1, it will scroll with constant speed, until the last point
private var _dragDecelarationFrictionCoef: CGFloat = 0.9

private var _tapGestureRecognizer: UITapGestureRecognizer!

public override init(frame: CGRect)
Expand All @@ -36,6 +42,11 @@ public class PieRadarChartViewBase: ChartViewBase
super.init(coder: aDecoder);
}

deinit
{
stopDeceleration();
}

internal override func initialize()
{
super.initialize();
Expand Down Expand Up @@ -335,6 +346,37 @@ public class PieRadarChartViewBase: ChartViewBase
public var isRotationEnabled: Bool { return rotationEnabled; }
/// :returns: true if chart continues to scroll after touch up, false if not.
/// :default: true
public var isDragDecelarationEnabled: Bool
{
return dragDecelarationEnabled;
}
/// Decelaration friction coefficient in [0 ; 1] interval, higher values indicate that speed will decrease slowly, for example if it set to 0, it will stop immediately, if set to 1, it will scroll with constant speed, until the last point
/// :default: true
public var dragDecelarationFrictionCoef: CGFloat
{
get
{
return _dragDecelarationFrictionCoef;
}
set
{
var val = newValue;
if (val > 1.0)
{
val = 1.0;
}
if (val < 0.0)
{
val = 0.0;
}
_dragDecelarationFrictionCoef = val;
}
}
// MARK: - Animation
private var _spinAnimator: ChartAnimator!;
Expand Down Expand Up @@ -381,15 +423,23 @@ public class PieRadarChartViewBase: ChartViewBase

// MARK: - Gestures

private var _touchStartPoint: CGPoint!;
private var _isRotating = false;
private var _defaultTouchesEventsWereEnabled = false;
private var _touchStartPoint: CGPoint!
private var _touchLastVelocityPoint: CGPoint!
private var _touchLastVelocityTime: NSTimeInterval = 0.0
private var _isRotating = false
private var _defaultTouchEventsWereEnabled = false
private var _startAngle = CGFloat(0.0)

private var _decelarationLastTime: NSTimeInterval = 0.0
private var _decelarationDisplayLink: CADisplayLink!
private var _decelarationAngularVelocity: CGFloat = 0.0

public override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent)
{
super.touchesBegan(touches, withEvent: event);

stopDeceleration();

// if rotation by touch is enabled
if (rotationEnabled)
{
Expand All @@ -398,7 +448,10 @@ public class PieRadarChartViewBase: ChartViewBase
var touchLocation = touch.locationInView(self);
_touchStartPoint = touchLocation;

self.setStartAngle(x: touchLocation.x, y: touchLocation.y);
_touchLastVelocityPoint = touchLocation;
_touchLastVelocityTime = CACurrentMediaTime();

self.setGestureStartAngle(x: touchLocation.x, y: touchLocation.y);
}
}

Expand All @@ -411,17 +464,30 @@ public class PieRadarChartViewBase: ChartViewBase
var touch = touches.first as! UITouch!;

var touchLocation = touch.locationInView(self);


var currentTime = CACurrentMediaTime();

let sampleTime: NSTimeInterval = 0.15,
stillTime: NSTimeInterval = 1.0,
stillTreshold: CGFloat = 15.0;

if ((currentTime - _touchLastVelocityTime >= sampleTime) &&
(distance(from: _touchLastVelocityPoint, to: touchLocation) > stillTreshold || _touchLastVelocityTime >= stillTime))
{
_touchLastVelocityPoint = touchLocation;
_touchLastVelocityTime = currentTime;
}

if (!_isRotating && distance(eventX: touchLocation.x, startX: _touchStartPoint.x, eventY: touchLocation.y, startY: _touchStartPoint.y) > CGFloat(8.0))
{
_isRotating = true;

_defaultTouchesEventsWereEnabled = self.defaultTouchEventsEnabled;
_defaultTouchEventsWereEnabled = self.defaultTouchEventsEnabled;
self.defaultTouchEventsEnabled = false;
}
else
{
self.updateRotation(x: touchLocation.x, y: touchLocation.y);
self.updateGestureRotation(x: touchLocation.x, y: touchLocation.y);
}
}
}
Expand All @@ -435,11 +501,26 @@ public class PieRadarChartViewBase: ChartViewBase
var touch = touches.first as! UITouch!;

var touchLocation = touch.locationInView(self);
_touchStartPoint = touchLocation;

if (isDragDecelarationEnabled)
{
stopDeceleration();

_decelarationLastTime = CACurrentMediaTime();

let deltaTime = CGFloat(_decelarationLastTime - _touchLastVelocityTime)

var newAngle = angleForPoint(x: touchLocation.x, y: touchLocation.y);
var previousAngle = angleForPoint(x: _touchLastVelocityPoint.x, y: _touchLastVelocityPoint.y);
_decelarationAngularVelocity = (newAngle - previousAngle) / deltaTime;

_decelarationDisplayLink = CADisplayLink(target: self, selector: Selector("decelerationLoop"));
_decelarationDisplayLink.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes);
}
}
if (_isRotating)
{
self.defaultTouchEventsEnabled = _defaultTouchesEventsWereEnabled;
self.defaultTouchEventsEnabled = _defaultTouchEventsWereEnabled;
_isRotating = false;
}
}
Expand All @@ -450,11 +531,38 @@ public class PieRadarChartViewBase: ChartViewBase

if (_isRotating)
{
self.defaultTouchEventsEnabled = _defaultTouchesEventsWereEnabled;
self.defaultTouchEventsEnabled = _defaultTouchEventsWereEnabled;
_isRotating = false;
}
}

public func stopDeceleration()
{
if (_decelarationDisplayLink !== nil)
{
_decelarationDisplayLink.removeFromRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes);
_decelarationDisplayLink = nil;
}
}

@objc private func decelerationLoop()
{
var currentTime = CACurrentMediaTime();

_decelarationAngularVelocity *= _dragDecelarationFrictionCoef;

var timeInterval = CGFloat(currentTime - _decelarationLastTime);

self.rotationAngle += _decelarationAngularVelocity * timeInterval;

_decelarationLastTime = currentTime;

if(abs(_decelarationAngularVelocity) < 0.001)
{
stopDeceleration();
}
}

/// returns the distance between two points
private func distance(#eventX: CGFloat, startX: CGFloat, eventY: CGFloat, startY: CGFloat) -> CGFloat
{
Expand All @@ -463,8 +571,16 @@ public class PieRadarChartViewBase: ChartViewBase
return sqrt(dx * dx + dy * dy);
}

/// returns the distance between two points
private func distance(#from: CGPoint, to: CGPoint) -> CGFloat
{
var dx = from.x - to.x;
var dy = from.y - to.y;
return sqrt(dx * dx + dy * dy);
}

/// sets the starting angle of the rotation, this is only used by the touch listener, x and y is the touch position
private func setStartAngle(#x: CGFloat, y: CGFloat)
private func setGestureStartAngle(#x: CGFloat, y: CGFloat)
{
_startAngle = angleForPoint(x: x, y: y);

Expand All @@ -475,7 +591,7 @@ public class PieRadarChartViewBase: ChartViewBase
}

/// updates the view rotation depending on the given touch position, also takes the starting angle into consideration
private func updateRotation(#x: CGFloat, y: CGFloat)
private func updateGestureRotation(#x: CGFloat, y: CGFloat)
{
self.rotationAngle = angleForPoint(x: x, y: y) - _startAngle;
}
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