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Added momentum scrolling and "rubber band" snap-back code from Travis…
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… Fischer.

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branch : momentumScrolling
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@eskroch
eskroch committed May 11, 2013
1 parent e51d44b commit dd70827
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Showing 4 changed files with 249 additions and 6 deletions.
2 changes: 1 addition & 1 deletion License.txt
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@@ -1,4 +1,4 @@
Copyright (c) 2012, Drew McCormack, Brad Larson, Eric Skroch, Barry Wark, Dirkjan Krijnders, Rick Maddy, Vijay Kalusani, Caleb Cannon, Jeff Buck, Thomas Elstner, Jeroen Leenarts, Craig Hockenberry, Hartwig Wiesmann, Koen van der Drift, Nino Ag, Mike Lischke, and Trevor Harmon.
Copyright (c) 2012, Drew McCormack, Brad Larson, Eric Skroch, Barry Wark, Dirkjan Krijnders, Rick Maddy, Vijay Kalusani, Caleb Cannon, Jeff Buck, Thomas Elstner, Jeroen Leenarts, Craig Hockenberry, Hartwig Wiesmann, Koen van der Drift, Nino Ag, Mike Lischke, Trevor Harmon, and Travis Fischer.
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
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2 changes: 2 additions & 0 deletions documentation/changelog.markdown
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Expand Up @@ -8,6 +8,8 @@ To be determined.
- **New**: Added support for styled text in all titles, labels, and text layers.
- **New**: Added a minor tick label shadow property to `CPTAxis`.
- **New**: Added a property to hide plot data labels.
- **New**: Added support for momentum scrolling.
- **New**: Added support for "rubber band" snap-back when scrolling reaches the global x- and y-ranges.
- **Changed**: Miscellaneous bug fixes and cleanup.


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14 changes: 14 additions & 0 deletions framework/Source/CPTXYPlotSpace.h
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Expand Up @@ -3,6 +3,13 @@

@class CPTPlotRange;

typedef enum _CPTRubberBandType {
kCPTRubberBandNone,
kCPTRubberBandLeft,
kCPTRubberBandRight
}
CPTRubberBandType;

@interface CPTXYPlotSpace : CPTPlotSpace {
@private
CPTPlotRange *xRange;
Expand All @@ -13,6 +20,9 @@
CPTScaleType yScaleType;
CGPoint lastDragPoint;
BOOL isDragging;
BOOL hasMomentum;
CPTRubberBandType rubberBand;
CGPoint momentum;
}

@property (nonatomic, readwrite, copy) CPTPlotRange *xRange;
Expand All @@ -22,4 +32,8 @@
@property (nonatomic, readwrite, assign) CPTScaleType xScaleType;
@property (nonatomic, readwrite, assign) CPTScaleType yScaleType;

@property (nonatomic, readwrite) BOOL allowsMomentum;
@property (nonatomic, readwrite) BOOL elasticGlobalXRange;
@property (nonatomic, readwrite) BOOL elasticGlobalYRange;

@end
237 changes: 232 additions & 5 deletions framework/Source/CPTXYPlotSpace.m
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Expand Up @@ -128,6 +128,7 @@ -(id)init
yScaleType = CPTScaleTypeLinear;
lastDragPoint = CGPointZero;
isDragging = NO;
hasMomentum = NO;
}
return self;
}
Expand Down Expand Up @@ -162,6 +163,9 @@ -(void)encodeWithCoder:(NSCoder *)coder
[coder encodeObject:self.globalYRange forKey:@"CPTXYPlotSpace.globalYRange"];
[coder encodeInt:self.xScaleType forKey:@"CPTXYPlotSpace.xScaleType"];
[coder encodeInt:self.yScaleType forKey:@"CPTXYPlotSpace.yScaleType"];
[coder encodeBool:self.allowsMomentum forKey:@"CPTXYPlotSpace.allowsMomentum"];
[coder encodeBool:self.elasticGlobalXRange forKey:@"CPTXYPlotSpace.elasticGlobalXRange"];
[coder encodeBool:self.elasticGlobalYRange forKey:@"CPTXYPlotSpace.elasticGlobalYRange"];

// No need to archive these properties:
// lastDragPoint
Expand All @@ -178,8 +182,13 @@ -(id)initWithCoder:(NSCoder *)coder
xScaleType = (CPTScaleType)[coder decodeIntForKey : @"CPTXYPlotSpace.xScaleType"];
yScaleType = (CPTScaleType)[coder decodeIntForKey : @"CPTXYPlotSpace.yScaleType"];

self.allowsMomentum = [coder decodeBoolForKey:@"CPTXYPlotSpace.allowsMomentum"];
self.elasticGlobalXRange = [coder decodeBoolForKey:@"CPTXYPlotSpace.elasticGlobalXRange"];
self.elasticGlobalYRange = [coder decodeBoolForKey:@"CPTXYPlotSpace.elasticGlobalYRange"];

lastDragPoint = CGPointZero;
isDragging = NO;
hasMomentum = NO;
}
return self;
}
Expand Down Expand Up @@ -272,7 +281,15 @@ -(void)setXRange:(CPTPlotRange *)range
NSParameterAssert(range);

if ( ![range isEqualToRange:xRange] ) {
CPTPlotRange *constrainedRange = [self constrainRange:range toGlobalRange:self.globalXRange];
CPTPlotRange *constrainedRange;

if ( self.elasticGlobalXRange ) {
constrainedRange = [range copy];
}
else {
constrainedRange = [self constrainRange:range toGlobalRange:self.globalXRange];
}

[xRange release];
xRange = [constrainedRange copy];

Expand All @@ -297,7 +314,15 @@ -(void)setYRange:(CPTPlotRange *)range
NSParameterAssert(range);

if ( ![range isEqualToRange:yRange] ) {
CPTPlotRange *constrainedRange = [self constrainRange:range toGlobalRange:self.globalYRange];
CPTPlotRange *constrainedRange;

if ( self.elasticGlobalXRange ) {
constrainedRange = [range copy];
}
else {
constrainedRange = [self constrainRange:range toGlobalRange:self.globalYRange];
}

[yRange release];
yRange = [constrainedRange copy];

Expand Down Expand Up @@ -822,8 +847,16 @@ -(void)scaleBy:(CGFloat)interactionScale aboutPoint:(CGPoint)plotAreaPoint
newRangeY = [theDelegate plotSpace:self willChangePlotRangeTo:newRangeY forCoordinate:CPTCoordinateY];
}

BOOL elasticGlobalXRange = self.elasticGlobalXRange;
BOOL elasticGlobalYRange = self.elasticGlobalYRange;
self.elasticGlobalXRange = NO;
self.elasticGlobalYRange = NO;

self.xRange = newRangeX;
self.yRange = newRangeY;

self.elasticGlobalXRange = elasticGlobalXRange;
self.elasticGlobalYRange = elasticGlobalYRange;
}

/// @endcond
Expand Down Expand Up @@ -858,7 +891,8 @@ -(BOOL)pointingDeviceDownEvent:(CPTNativeEvent *)event atPoint:(CGPoint)interact
BOOL handledByDelegate = [super pointingDeviceDownEvent:event atPoint:interactionPoint];

if ( handledByDelegate ) {
isDragging = NO;
isDragging = NO;
hasMomentum = NO;
return YES;
}

Expand All @@ -872,6 +906,9 @@ -(BOOL)pointingDeviceDownEvent:(CPTNativeEvent *)event atPoint:(CGPoint)interact
// Handle event
lastDragPoint = pointInPlotArea;
isDragging = YES;
hasMomentum = NO;
rubberBand = kCPTRubberBandNone;

return YES;
}

Expand Down Expand Up @@ -909,7 +946,17 @@ -(BOOL)pointingDeviceUpEvent:(CPTNativeEvent *)event atPoint:(CGPoint)interactio
}

if ( isDragging ) {
isDragging = NO;
isDragging = NO;
hasMomentum = self.allowsMomentum;
rubberBand = kCPTRubberBandNone;

if ( self.allowsMomentum ) {
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC / 60), dispatch_get_current_queue(), ^{
[self handleMomentum];
}
);
}

return YES;
}

Expand Down Expand Up @@ -961,6 +1008,8 @@ -(BOOL)pointingDeviceDraggedEvent:(CPTNativeEvent *)event atPoint:(CGPoint)inter
pointToUse = CPTPointMake(lastDragPoint.x + displacement.x, lastDragPoint.y + displacement.y);
}

momentum = displacement;

NSDecimal lastPoint[2], newPoint[2];
[self plotPoint:lastPoint forPlotAreaViewPoint:lastDragPoint];
[self plotPoint:newPoint forPlotAreaViewPoint:pointToUse];
Expand All @@ -975,8 +1024,31 @@ -(BOOL)pointingDeviceDraggedEvent:(CPTNativeEvent *)event atPoint:(CGPoint)inter

CPTPlotRange *globalX = self.globalXRange;
if ( globalX ) {
newRangeX = (CPTMutablePlotRange *)[self constrainRange:newRangeX toGlobalRange:globalX];
if ( !self.elasticGlobalXRange ) {
newRangeX = (CPTMutablePlotRange *)[self constrainRange:newRangeX toGlobalRange:globalX];
}
else if ( newRangeX.locationDouble < globalX.locationDouble ) {
if ( shiftX._isNegative ) {
NSDecimal diff = CPTDecimalDivide(CPTDecimalSubtract(globalX.location, newRangeX.location), newRangeX.length);
diff = CPTDecimalFromDouble( MIN(1.0, [[NSDecimalNumber decimalNumberWithDecimal:CPTDecimalMultiply( diff, CPTDecimalFromDouble(3.0) )] doubleValue]) );

// diff=1 => no scaling
// diff=0 => full scaling
newRangeX.location = CPTDecimalAdd( self.xRange.location, CPTDecimalMultiply( shiftX, CPTDecimalSubtract(CPTDecimalFromDouble(1.0), diff) ) );
}
}
else if ( newRangeX.endDouble > globalX.endDouble ) {
if ( !shiftX._isNegative ) {
NSDecimal diff = CPTDecimalDivide(CPTDecimalSubtract(newRangeX.end, globalX.end), newRangeX.length);
diff = CPTDecimalFromDouble( MIN(1.0, [[NSDecimalNumber decimalNumberWithDecimal:CPTDecimalMultiply( diff, CPTDecimalFromDouble(3.0) )] doubleValue]) );

// diff=1 => no scaling
// diff=0 => full scaling
newRangeX.location = CPTDecimalAdd( self.xRange.location, CPTDecimalMultiply( shiftX, CPTDecimalSubtract(CPTDecimalFromDouble(1.0), diff) ) );
}
}
}

CPTPlotRange *globalY = self.globalYRange;
if ( globalY ) {
newRangeY = (CPTMutablePlotRange *)[self constrainRange:newRangeY toGlobalRange:globalY];
Expand All @@ -1000,6 +1072,161 @@ -(BOOL)pointingDeviceDraggedEvent:(CPTNativeEvent *)event atPoint:(CGPoint)inter
return NO;
}

-(void)handleMomentum
{
CPTPlotArea *plotArea = self.graph.plotAreaFrame.plotArea;

if ( !self.allowsUserInteraction || !plotArea || !hasMomentum || !self.allowsMomentum ) {
return;
}

CGPoint pointToUse = CPTPointMake(lastDragPoint.x + momentum.x, lastDragPoint.y + momentum.y);

id<CPTPlotSpaceDelegate> theDelegate = self.delegate;

CGFloat friction = 0.9f;
CPTPlotRange *globalX = self.globalXRange;
CPTPlotRange *globalY = self.globalYRange;

if ( rubberBand != kCPTRubberBandNone ) {
NSDecimal diff;

if ( rubberBand == kCPTRubberBandLeft ) {
diff = CPTDecimalSubtract(globalX.location, self.xRange.location);
}
else {
diff = CPTDecimalSubtract(self.xRange.end, globalX.end);
}

diff = CPTDecimalDivide(diff, self.xRange.length);
diff = CPTDecimalFromDouble( MIN(1.0, [[NSDecimalNumber decimalNumberWithDecimal:CPTDecimalMultiply( diff, CPTDecimalFromDouble(3.0) )] doubleValue]) );

// diff=0 => friction=0.9
// diff=1 => friction=0.6
friction = 0.9f - ([[NSDecimalNumber decimalNumberWithDecimal:diff] floatValue]) * 0.25f;
// NSLog(@"rubberBand %f; %f", momentum.x, friction);
}

momentum = CPTPointMake(momentum.x * friction, momentum.y * friction);

NSDecimal lastPoint[2], newPoint[2];
[self plotPoint:lastPoint forPlotAreaViewPoint:lastDragPoint];
[self plotPoint:newPoint forPlotAreaViewPoint:pointToUse];

CPTMutablePlotRange *newRangeX = [[self.xRange mutableCopy] autorelease];
CPTMutablePlotRange *newRangeY = [[self.yRange mutableCopy] autorelease];

NSDecimal shiftX = CPTDecimalSubtract(lastPoint[0], newPoint[0]);
NSDecimal shiftY = CPTDecimalSubtract(lastPoint[1], newPoint[1]);

if ( rubberBand != kCPTRubberBandNone ) {
if ( rubberBand == kCPTRubberBandLeft ) {
shiftX._isNegative = 0;
}
else if ( rubberBand == kCPTRubberBandRight ) {
shiftX._isNegative = 1;
}
}

newRangeX.location = CPTDecimalAdd(newRangeX.location, shiftX);
newRangeY.location = CPTDecimalAdd(newRangeY.location, shiftY);

if ( globalX ) {
if ( !self.elasticGlobalXRange ) {
newRangeX = (CPTMutablePlotRange *)[self constrainRange:newRangeX toGlobalRange:globalX];
}
else {
if ( newRangeX.locationDouble < globalX.locationDouble ) {
if ( rubberBand == kCPTRubberBandNone ) {
NSDecimal diff = CPTDecimalDivide(CPTDecimalSubtract(globalX.location, newRangeX.location), newRangeX.length);
diff = CPTDecimalFromDouble( MIN(1.0, [[NSDecimalNumber decimalNumberWithDecimal:CPTDecimalMultiply( diff, CPTDecimalFromDouble(3.0) )] doubleValue]) );

// slow momentum down faster past global range bounds
friction = 0.9f - ([[NSDecimalNumber decimalNumberWithDecimal:diff] floatValue]) / 3.0f;
momentum = CPTPointMake(momentum.x * friction, momentum.y);

// diff=1 => no scaling
// diff=0 => full scaling
newRangeX.location = CPTDecimalAdd( self.xRange.location, CPTDecimalMultiply( shiftX, CPTDecimalSubtract(CPTDecimalFromDouble(1.0), diff) ) );
}
}
else if ( newRangeX.endDouble > globalX.endDouble ) {
if ( rubberBand == kCPTRubberBandNone ) {
NSDecimal diff = CPTDecimalDivide(CPTDecimalSubtract(newRangeX.end, globalX.end), newRangeX.length);
diff = CPTDecimalFromDouble( MIN(1.0, [[NSDecimalNumber decimalNumberWithDecimal:CPTDecimalMultiply( diff, CPTDecimalFromDouble(3.0) )] doubleValue]) );

// slow momentum down faster past global range bounds
friction = 0.9f - ([[NSDecimalNumber decimalNumberWithDecimal:diff] floatValue]) / 3.0f;
momentum = CPTPointMake(momentum.x * friction, momentum.y);

// diff=1 => no scaling
// diff=0 => full scaling
newRangeX.location = CPTDecimalAdd( self.xRange.location, CPTDecimalMultiply( shiftX, CPTDecimalSubtract(CPTDecimalFromDouble(1.0), diff) ) );
}
}
else if ( rubberBand != kCPTRubberBandNone ) {
if ( rubberBand == kCPTRubberBandLeft ) {
newRangeX.location = globalX.location;
}
else if ( rubberBand == kCPTRubberBandRight ) {
newRangeX.location = CPTDecimalSubtract(globalX.end, newRangeX.length);
}

rubberBand = NO;
hasMomentum = NO;
}
}
}

if ( globalY ) {
newRangeY = (CPTMutablePlotRange *)[self constrainRange:newRangeY toGlobalRange:globalY];
}

// Delegate override
if ( [theDelegate respondsToSelector:@selector(plotSpace:willChangePlotRangeTo:forCoordinate:)] ) {
self.xRange = [theDelegate plotSpace:self willChangePlotRangeTo:newRangeX forCoordinate:CPTCoordinateX];
self.yRange = [theDelegate plotSpace:self willChangePlotRangeTo:newRangeY forCoordinate:CPTCoordinateY];
}
else {
self.xRange = newRangeX;
self.yRange = newRangeY;
}

lastDragPoint = pointToUse;

if ( hasMomentum ) {
if ( ABS(momentum.x) < 0.5 ) {
CGFloat rubberBandMomentum = 22.0f;

if ( rubberBand != kCPTRubberBandNone ) {
momentum = CGPointMake(momentum.x / friction, momentum.y / friction);
}
else {
if ( globalX && (self.xRange.locationDouble < globalX.locationDouble) ) {
momentum.x = rubberBandMomentum;
rubberBand = kCPTRubberBandLeft;
// NSLog(@"rubberBand left");
}
else if ( globalX && (self.xRange.endDouble > globalX.endDouble) ) {
momentum.x = -rubberBandMomentum;
rubberBand = kCPTRubberBandRight;
// NSLog(@"rubberBand right");
}
else {
hasMomentum = NO;
}
}
}

if ( hasMomentum ) {
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC / 60), dispatch_get_current_queue(), ^{
[self handleMomentum];
}
);
}
}
}

/// @}

@end

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