A simple finger trail extension for Sparrow

SHFingerTrail.h

//
//  SHFingerTrail.h
//  FingerTrailSample
//
//  Created by Shilo White on 3/28/11.
//  Copyright 2011 Shilocity Productions. All rights reserved.
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the Simplified BSD License.
//

typedef enum {    
	SHFingerTrailStyleSpiky,
	SHFingerTrailStyleBubbly,
	SHFingerTrailStyleSlinky,
} SHFingerTrailStyle;

#import <Foundation/Foundation.h>
#import "SPSprite.h"
@class SPJuggler;

@interface SHFingerTrail : SPSprite {
	SPJuggler *mJuggler;
	SHFingerTrailStyle mStyle;
	float mTime;
	float mSize;
	int mMaxNumberOfFingers;
	BOOL mAlwaysOnTop;
	BOOL mShowOnTouchBegin;
	BOOL mFade;
	uint mInnerColor;
	uint mOuterColor;
	float mGradient[12];
}

@property (nonatomic, assign) SHFingerTrailStyle style;
@property (nonatomic, assign) float time;
@property (nonatomic, assign) float size;
@property (nonatomic, assign) BOOL alwaysOnTop;
@property (nonatomic, assign) BOOL showOnTouchBegin;
@property (nonatomic, assign) BOOL fade;
@property (nonatomic, assign) uint color;
@property (nonatomic, assign) uint innerColor;
@property (nonatomic, assign) uint outerColor;


- (id)initWithTime:(float)time;
- (id)initWithTime:(float)time size:(float)size;
+ (SHFingerTrail *)fingerTrail;
+ (SHFingerTrail *)fingerTrailWithTime:(float)time;
+ (SHFingerTrail *)fingerTrailWithTime:(float)time size:(float)size;
@end

SHFingerTrail.m

//
//  SHFingerTrail.m
//  FingerTrailSample
//
//  Created by Shilo White on 3/28/11.
//  Copyright 2011 Shilocity Productions. All rights reserved.
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the Simplified BSD License.
//

#define SP_COLOR_PART_RED(color)    (((color) >> 16) & 0xff)
#define SP_COLOR_PART_GREEN(color)  (((color) >>  8) & 0xff)
#define SP_COLOR_PART_BLUE(color)   ( (color)        & 0xff)

#import "SHFingerTrail.h"
#import "SPTouchEvent.h"
#import	"SPEnterFrameEvent.h"
#import "SPPoint.h"
#import "SPTween.h"
#import "SPJuggler.h"
#import "SPStage.h"
#import "SPTexture.h"
#import "SPImage.h"
#import "SPDisplayObjectContainer.h"

@interface SHFingerTrail ()
- (void)setGradient;
- (void)drawTrailWithCurrentLocation:(SPPoint *)currentLocation previousLocation:(SPPoint *)previousLocation;
- (void)startTweenWithTrail:(SPSprite *)target distance:(float)distance;
@end


@implementation SHFingerTrail

@synthesize style = mStyle;
@synthesize time = mTime;
@synthesize size = mSize;
@synthesize alwaysOnTop = mAlwaysOnTop;
@synthesize showOnTouchBegin = mShowOnTouchBegin;
@synthesize fade = mFade;
@synthesize innerColor = mInnerColor;
@synthesize outerColor = mOuterColor;

- (id)init {
	return [self initWithTime:0.2f];
}

- (id)initWithTime:(float)time {
	return [self initWithTime:time size:30.0f];
}

- (id)initWithTime:(float)time size:(float)size {
	if (self = [super init]) {
		mStyle = SHFingerTrailStyleSpiky;
		mTime = time;
		mSize = size;
		mInnerColor = 0xadd8e6;
		mOuterColor = 0x0000ff;
		[self setGradient];
		[self addEventListener:@selector(onAddedToStage:) atObject:self forType:SP_EVENT_TYPE_ADDED_TO_STAGE];
		[self addEventListener:@selector(onRemovedFromStage:) atObject:self forType:SP_EVENT_TYPE_REMOVED_FROM_STAGE];
	}
	return self;
}

+ (SHFingerTrail *)fingerTrail {
	return [[[SHFingerTrail alloc] init] autorelease];
}

+ (SHFingerTrail *)fingerTrailWithTime:(float)time {
	return [[[SHFingerTrail alloc] initWithTime:time] autorelease];
}

+ (SHFingerTrail *)fingerTrailWithTime:(float)time size:(float)size {
	return [[[SHFingerTrail alloc] initWithTime:time size:size] autorelease];
}

- (void)setInnerColor:(uint)innerColor {
	if (innerColor != mInnerColor) {
		mInnerColor = innerColor;
		[self setGradient];
	}
}

- (void)setOuterColor:(uint)outerColor {
	if (outerColor != mOuterColor) {
		mOuterColor = outerColor;
		[self setGradient];
	}
}

- (void)setColor:(uint)color {
	mInnerColor = mOuterColor = color;
	[self setGradient];
}

- (uint)color {
	return mInnerColor;
}

- (void)setAlwaysOnTop:(BOOL)alwaysOnTop {
	if (alwaysOnTop != mAlwaysOnTop) {
		mAlwaysOnTop = alwaysOnTop;
		if (mAlwaysOnTop) [self addEventListener:@selector(checkOnTop:) atObject:self forType:SP_EVENT_TYPE_ENTER_FRAME];
		else [self removeEventListener:@selector(checkOnTop:) atObject:self forType:SP_EVENT_TYPE_ENTER_FRAME];
	}
}

- (void)checkOnTop:(SPEnterFrameEvent *)event {
	SPDisplayObjectContainer *parent = self.parent;
	if ([parent childIndex:self] < parent.numChildren-1) [parent addChild:self];
}

- (void)onAddedToStage:(SPEvent *)event {
	[self.stage addEventListener:@selector(onTouch:) atObject:self forType:SP_EVENT_TYPE_TOUCH];
	SPStage *stage = (SPStage *)self.stage;
	mJuggler = stage.juggler;
}

- (void)onRemovedFromStage:(SPEvent *)event {
	[self.stage removeEventListener:@selector(onTouch:) atObject:self forType:SP_EVENT_TYPE_TOUCH];
	mJuggler = nil;
}

- (void)onTouch:(SPTouchEvent *)event {
	NSArray *touches = [[event touches] allObjects];
	
	for (SPTouch *touch in touches) {
		if (touch.phase == SPTouchPhaseBegan && mShowOnTouchBegin || touch.phase == SPTouchPhaseMoved) {
			[self drawTrailWithCurrentLocation:[touch locationInSpace:self] previousLocation:[touch previousLocationInSpace:self]];
		}
	}
}

- (void)setGradient {
	mGradient[0] = SP_COLOR_PART_RED(mOuterColor);
	mGradient[1] = SP_COLOR_PART_GREEN(mOuterColor);
	mGradient[2] = SP_COLOR_PART_BLUE(mOuterColor);
	mGradient[3] = 1.0f;
	mGradient[4] = SP_COLOR_PART_RED(mInnerColor);
	mGradient[5] = SP_COLOR_PART_GREEN(mInnerColor);
	mGradient[6] = SP_COLOR_PART_BLUE(mOuterColor);
	mGradient[7] = 1.0f;
	mGradient[8] = SP_COLOR_PART_RED(mOuterColor);
	mGradient[9] = SP_COLOR_PART_GREEN(mOuterColor);
	mGradient[10] = SP_COLOR_PART_BLUE(mOuterColor);
	mGradient[11] = 1.0f;
}

- (void)drawTrailWithCurrentLocation:(SPPoint *)currentLocation previousLocation:(SPPoint *)previousLocation {
	float radius = mSize/2;
	float distance = [SPPoint distanceFromPoint:previousLocation toPoint:currentLocation];
	SPTexture *trailTexture = [[SPTexture alloc] initWithWidth:mSize height:distance+mSize
	draw:^(CGContextRef context) {
		CGContextBeginTransparencyLayer(context, NULL);
		
		CGContextSetLineWidth(context, mSize);
		CGContextSetLineCap(context, kCGLineCapRound);
		CGContextMoveToPoint(context, radius, radius);
		CGContextAddLineToPoint(context, radius, distance+radius);
		CGContextStrokePath(context);
		
		CGContextSetBlendMode(context, kCGBlendModeSourceIn);
		
		CGColorSpaceRef baseSpace = CGColorSpaceCreateDeviceRGB();
		CGGradientRef gradient = CGGradientCreateWithColorComponents(baseSpace, mGradient, NULL, 3);
		CGColorSpaceRelease(baseSpace);
		baseSpace = NULL;
		
		CGContextDrawLinearGradient(context, gradient, CGPointMake(0, (distance+mSize)/2), CGPointMake(mSize, (distance+mSize)/2), 0);
		CGGradientRelease(gradient);
		gradient = NULL;
		
		CGContextEndTransparencyLayer(context);
	}];
	
	SPImage *trailImage = [[SPImage alloc] initWithTexture:trailTexture];
	trailImage.x = -ceil(radius);
	trailImage.y = -ceil(radius);
	
	SPSprite *trailSprite = [[SPSprite alloc] init];
	trailSprite.x = currentLocation.x;
	trailSprite.y = currentLocation.y;
	trailSprite.rotation = atan2(currentLocation.x-previousLocation.x, previousLocation.y-currentLocation.y);
	[trailSprite addChild:trailImage];
	
	[self addChild:trailSprite];
	[self startTweenWithTrail:trailSprite distance:distance];
	
	[trailSprite release];
	[trailImage release];
	[trailTexture release];
}

- (void)startTweenWithTrail:(SPSprite *)target distance:(float)distance {
	SPTween *tween = [SPTween tweenWithTarget:target time:mTime];
	
	switch (mStyle) {
		case SHFingerTrailStyleSpiky:
			[tween animateProperty:@"scaleX" targetValue:0];
			if (distance < 5) [tween animateProperty:@"scaleY" targetValue:0];
			break;
		case SHFingerTrailStyleBubbly:
			[tween animateProperty:@"scaleX" targetValue:0];
			[tween animateProperty:@"scaleY" targetValue:0];
			break;
		case SHFingerTrailStyleSlinky:
			[tween animateProperty:@"scaleY" targetValue:0];
			break;
	}
	if (mFade) [tween animateProperty:@"alpha" targetValue:0];
	
	[tween addEventListener:@selector(onTweenCompleted:) atObject:self forType:SP_EVENT_TYPE_TWEEN_COMPLETED];
	[mJuggler addObject:tween];
}

- (void)onTweenCompleted:(SPEvent *)event {
	SPTween *tween = (SPTween *)event.target;
	[tween removeEventListener:@selector(onTweenCompleted:) atObject:self forType:SP_EVENT_TYPE_TWEEN_COMPLETED];
	[self removeChild:(SPDisplayObject *)tween.target];
}
@end