#import "cocos2d.h"@class SZSimplePhysicsDragSelector;
@protocol SZSimplePhysicsDragSelectorDelegate <NSObject>
@optional
// call when the selected icon changes
-(void)onSelectedIconChanged:(SZSimplePhysicsDragSelector*)selector;
@end@interface SZSimplePhysicsDragSelector : CCLayer
{CCNode *s_content;//所有节点图标的父节点NSMutableArray *s_icons;//节点图标清单CCNode *s_selectedIcon;//选定的节点
    BOOL isDragging;//是否在拖拽状态CGPoint lastTouchPoint;//上一个触摸点float lastx;//上一个图层内容x坐标float xvel;//内容在x轴上的速度int maxX;//内容可以自然移动到的最大极限x坐标int minX;//内容可以自然移动到的最小极限x坐标float acceleration;//加速度float f;//合外力id<SZSimplePhysicsDragSelectorDelegate> s_delegate;//代理
}@property (nonatomic, readonly) NSMutableArray *Icons;
@property (nonatomic, readonly) CCNode *SelectedIcon;
@property (nonatomic, assign) id<SZSimplePhysicsDragSelectorDelegate> Delegate;- (id)initWithIcons:(NSArray*)icons;@end

@implementation SZSimplePhysicsDragSelector@synthesize Delegate = s_delegate;
@synthesize Icons = s_icons;
@synthesize SelectedIcon = s_selectedIcon;- (id)initWithIcons:(NSArray *)icons
{self = [super init];if (self) {s_icons = [[NSMutableArray alloc] initWithArray:icons];s_content = nil;s_selectedIcon = nil;isDragging = NO;lastTouchPoint = CGPointZero;lastx = 0.0f;xvel = 0.0f;minX = 0;maxX = 0;acceleration = 0.0f;f = 0.0f;self.isTouchEnabled = true;// 启用接收触摸事件
        s_delegate = nil;}return self;
}- (void)dealloc
{[s_icons release];[super dealloc];
}#pragma mark Override methods-(void) onEnter
{[super onEnter];s_content = [[CCSprite alloc]init];[self addChild:s_content];[self scheduleUpdate];//开启计时器
}-(void) onExit
{[self unscheduleUpdate];//关闭计时器
    [self removeChild:s_content cleanup:YES];[s_content release];s_content = nil;s_selectedIcon = nil;[super onExit];
}@end

-(void) onEnter
{[super onEnter];s_content = [[CCSprite alloc]init];[self addChild:s_content];[self layout];[self scheduleUpdate];
}-(void) layout
{int i = 1;for (CCNode *icon in s_icons) {CGPoint position = ccp((i-1) * 180, 0);float distance = fabsf(icon.position.x)/100;icon.position = position;if (![s_content.children containsObject:icon]) {[s_content addChild:icon];}i++;}s_selectedIcon = [s_icons lastObject];if ([s_delegate respondsToSelector:@selector(onSelectedIconChanged:)]) {[s_delegate onSelectedIconChanged:self];}minX = - (i-1) * 180 - 100;maxX = 100;
}

- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
{s_selectedIcon = nil;if ([s_delegate respondsToSelector:@selector(onSelectedIconChanged:)]) {[s_delegate onSelectedIconChanged:self];}UITouch *touch = [touches anyObject];CGPoint position = [self convertTouchToNodeSpace:touch];lastTouchPoint = position;isDragging = true;
}- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
{UITouch *touch = [touches anyObject];CGPoint position = [self convertTouchToNodeSpace:touch];CGPoint translate = ccpSub(position, lastTouchPoint);translate.y = 0;s_content.position = ccpAdd(s_content.position, translate);lastTouchPoint = position;
}- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
{isDragging = false;
}- (void)ccTouchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
{isDragging = false;
}

-(void) update:(ccTime)dt;
{[self updateMove:dt];
}- (void) updateMove:(ccTime)dt
{if ( !isDragging ){// *** CHANGE BEHAVIOR HERE *** //
        float F1 = 0.0f;float F2 = 0.0f;float F3 = 0.0f;CGPoint pos = s_content.position;//F1// frictionF1 = - xvel * 0.1;//F2// prevent icons out of rangeif ( pos.x < minX ){F2 = (minX - pos.x);}else if ( pos.x > maxX ){F2 = (maxX - pos.x);}//F3// suck planetif (fabsf(xvel) < 100 && !s_selectedIcon) {CCNode *nearestIcon = nil;for (CCNode *icon in s_icons) {if (nearestIcon) {CGPoint pt1 = [icon.parent convertToWorldSpace:icon.position];float distance1 = fabsf(pt1.x - [CCDirector sharedDirector].winSize.width/2);CGPoint pt2 = [nearestIcon.parent convertToWorldSpace:nearestIcon.position];float distance2 = fabsf(pt2.x - [CCDirector sharedDirector].winSize.width/2);if (distance1 < distance2) {nearestIcon = icon;}}else {nearestIcon = icon;}}if (nearestIcon) {s_selectedIcon = nearestIcon;if ([s_delegate respondsToSelector:@selector(onSelectedIconChanged:)]) {[s_delegate onSelectedIconChanged:self];}}}if (s_selectedIcon) {CGPoint pt = [s_selectedIcon.parent convertToWorldSpace:s_selectedIcon.position];;float distance = pt.x - [CCDirector sharedDirector].winSize.width/2;F3 = - distance;}//CALCULATEf = F1 + F2 + F3;acceleration = f/1;xvel += acceleration;pos.x += xvel*dt;s_content.position = pos;}else{xvel = ( s_content.position.x - lastx ) / dt;lastx = s_content.position.x;}
}

-(void) layout
{int i = 1;for (CCNode *icon in s_icons) {CGPoint position = ccp((i-1) * 180, 0);float distance = fabsf(icon.position.x)/100;float scale = 1/(1+distance);icon.position = position;icon.scale = scale;//初始化缩放比例if (![s_content.children containsObject:icon]) {[s_content addChild:icon];}i++;}s_selectedIcon = [s_icons lastObject];if ([s_delegate respondsToSelector:@selector(onSelectedIconChanged:)]) {[s_delegate onSelectedIconChanged:self];}minX = - (i-1) * 180 - 100;maxX = 100;
}-(void) update:(ccTime)dt;
{[self updateMove:dt];
    [self updateScale:dt];//更新缩放比例}-(void) updateScale:(ccTime)dt;
{for (CCNode *icon in s_icons) {CGPoint pt = [self convertToNodeSpace:[icon.parent convertToWorldSpace:icon.position]];float distance = fabsf(pt.x)/100;icon.scale = 1/(1+distance);}
}

        // create and initialize a LabelCCLabelTTF *label = [CCLabelTTF labelWithString:@"Sawyer's Test" fontName:@"Marker Felt" fontSize:64];// ask director for the window sizeCGSize size = [[CCDirector sharedDirector] winSize];// position the label on the center of the screenlabel.position =  ccp( size.width /2 , size.height/2 );// add the label as a child to this Layer
        [self addChild: label];// add the test selector to the layerNSMutableArray *icons = [NSMutableArray array];int i = 10;while (i) {[icons addObject:[CCSprite spriteWithFile:@"Icon@2x.png"]];i--;}SZSimplePhysicsDragSelector *selector = [[[SZSimplePhysicsDragSelector alloc] initWithIcons:icons] autorelease];selector.position = self.anchorPointInPoints;        selector.Delegate = self;[self addChild:selector];