大家好,今天是2015年的最后一天,在这里先祝大家新年快乐,在新的一年里打代码没bug.
好了,今天要讲的是贝塞尔曲线的简单应用.大家在用app的时候不知道有没有注意到有些app里,当你向右滑动屏幕时,如果没有内容的话会从屏幕坐标向右出现一个曲线阴影,而且阴影的形状是根据手指的位置以及滑动程度来决定的,效果图如下.
那这是怎么做到的呢,看看代码大家就知道了,代码注释的很详细,相信大家能看懂,如果想深入研究贝塞尔曲线,大家可以上网查查.
自定义的View
//
// XMHView.m
// XMHDragView
//
// Created by 徐茂怀 on 15/12/31.
// Copyright © 2015年 徐茂怀. All rights reserved.
//
#import "XMHView.h"
#define WIDTH [UIScreen mainScreen].bounds.size.width
#define HEIGHT [UIScreen mainScreen].bounds.size.height
@interface XMHView ()
@property(nonatomic, strong) UIView *dotOne; //这是个小点,向下滑动时改变其Point,从而绘制贝塞尔曲线
@property(nonatomic, assign) CGFloat dotOneX; //dotOne的x坐标,当滑动时会改变
@property(nonatomic, assign) CGFloat dotOneY; //dotOne的y坐标,当滑动时会改变
@property(nonatomic, strong) CAShapeLayer *dotOneShapeLayer;//这是滑动时出现的那个曲面
/**下面的和上面的对应,上面是向下滑动时的点,下面是向右滑动时的点*/
@property(nonatomic, assign) CGFloat maxWidth;
@property(nonatomic, strong) UIView *dotTwo;
@property(nonatomic, assign) CGFloat dotTwoX;
@property(nonatomic, assign) CGFloat dotTwoY;
@property(nonatomic, strong) CAShapeLayer *dotTwoShapeLayer;
@property(nonatomic, strong) CADisplayLink *dotTwoDisPlayLink;
@property(nonatomic, assign)BOOL isAnimating;
@property(nonatomic, strong) CADisplayLink *disPlayLink;//这相当于一个定时器,不同于NSTimer的是NSTimer一旦初始化它就开始运行，而CADisplayLink需要将显示链接添加到一个运行循环中，即用于处理系统事件的一个Cocoa Touch结构,还有就是NSTimer我们通常会用在背景计算，更新一些数值资料，而如果牵涉到画面的更新，动画过程的演变，我们通常会用CADisplayLink。
@end
@implementation XMHView
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.alpha = .4;
[self addGesture];
[self configDotView];
[self initShapeLayer];
[self updateShapeLayerPath];
}
return self;
}
#pragma mark-添加手势和displaylink
-(void)addGesture
{
_isAnimating = NO;//是否处于动画状态
// 添加滑动手势
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanAction:)];
self.userInteractionEnabled = YES;
[self addGestureRecognizer:pan];
// CADisplayLink默认每秒运行60次calculatePath是算出在运行期间_curveView的坐标，从而确定_shapeLayer的形状
_disPlayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(calculatePath)];
[_disPlayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];//之前说过CADisplayLink需要添加到运行时中
_disPlayLink.paused = YES;
}
#pragma mark -初始化shapeLayer并将其颜色设置为灰色
-(void)initShapeLayer
{
_dotOneShapeLayer = [CAShapeLayer layer];
_dotOneShapeLayer.fillColor = [UIColor grayColor].CGColor;
[self.layer addSublayer:_dotOneShapeLayer];
_dotTwoShapeLayer = [CAShapeLayer layer];
_dotTwoShapeLayer.fillColor = [UIColor grayColor].CGColor;
[self.layer addSublayer:_dotTwoShapeLayer];
}
#pragma mark -初始化2个小点
- (void)configDotView
{
_dotOne = [[UIView alloc] initWithFrame:CGRectMake(WIDTH / 2.0, 0, 3, 3)];
_dotTwo = [[UIView alloc] initWithFrame:CGRectMake(0, HEIGHT / 2, 3, 3)];
[self addSubview:_dotOne];
[self addSubview:_dotTwo];
}
#pragma mark -当滑动时改变小点的point
- (void)handlePanAction:(UIPanGestureRecognizer *)pan
{
if(!_isAnimating)
{
if(pan.state == UIGestureRecognizerStateChanged)
{
CGPoint point = [pan translationInView:self];
// 这部分代码使dotOne跟着手势走
CGFloat dotOneHeight = point.y * 0.7;
_dotOneX = WIDTH / 2.0 + point.x;
_dotOneY = dotOneHeight ;
_dotOne.frame = CGRectMake(_dotOneX,_dotOneY,_dotOne.frame.size.width,_dotOne.frame.size.height);
// 根据r5的坐标,更新_shapeLayer形状
CGFloat dotTwoWidth = point.x * 0.7 ;
_dotTwoX = dotTwoWidth;
_dotTwoY = HEIGHT / 2.0 + point.y;
_dotTwo.frame = CGRectMake(_dotTwoX, _dotTwoY, _dotTwo.frame.size.width, _dotTwo.frame.size.height);
[self updateShapeLayerPath];//当小点point改变,各自的shaplayer也会跟着变
}
else if (pan.state == UIGestureRecognizerStateCancelled ||
pan.state == UIGestureRecognizerStateEnded ||
pan.state == UIGestureRecognizerStateFailed)
{
// 手势结束时,_shapeLayer返回原状并产生弹簧动效
_isAnimating = YES;
_disPlayLink.paused = NO; //开启displaylink,会执行方法calculatePath.
// 弹簧动效,因为各自的shapelayer是根据各自的点动,当小点有弹簧效果,那么shapelayer也会有弹簧效果
[UIView animateWithDuration:1.0
delay:0.0
usingSpringWithDamping:1.0
initialSpringVelocity:0
options:UIViewAnimationOptionCurveEaseInOut
animations:^{
_dotOne.frame = CGRectMake(WIDTH / 2.0, 0, 3, 3);
_dotTwo.frame = CGRectMake(0, HEIGHT / 2.0, 3, 3);
} completion:^(BOOL finished) {
if(finished)
{
_disPlayLink.paused = YES;
_isAnimating = NO;
}
}];
}
}
}
- (void)updateShapeLayerPath
{
// 更新_shapeLayer形状,贝塞尔曲线其实就是根据一天直线和一个点描绘出一条曲线,以向下滑动为例,首先确定一条直线,这条直线就是从(0,0)到(WIDTH,0)这个线,然后就可以根据dotOne的point去描绘这条曲线了
UIBezierPath *dotOnePath = [UIBezierPath bezierPath];
[dotOnePath moveToPoint:CGPointMake(0, 0)];
[dotOnePath addLineToPoint:CGPointMake(WIDTH, 0)];
[dotOnePath addQuadCurveToPoint:CGPointMake(0, 0)
controlPoint:CGPointMake(_dotOneX, _dotOneY)];
[dotOnePath closePath];
_dotOneShapeLayer.path = dotOnePath.CGPath;
UIBezierPath *dotTwoPath = [UIBezierPath bezierPath];
[dotTwoPath moveToPoint:CGPointMake(0, 0)];
[dotTwoPath addLineToPoint:CGPointMake(0, HEIGHT)];
[dotTwoPath addQuadCurveToPoint:CGPointMake(0, 0) controlPoint:CGPointMake(_dotTwoX, _dotTwoY)];
[dotTwoPath closePath];
_dotTwoShapeLayer.path = dotTwoPath.CGPath;
}
- (void)calculatePath
{
// 由于手势结束时,dotOne和dotTwo执行了一个UIView的弹簧动画,把这个过程的坐标记录下来,并相应的画出各自的shapeLayer形状
CALayer *dotOnelayer = _dotOne.layer.presentationLayer;
_dotOneX = dotOnelayer.position.x;
_dotOneY = dotOnelayer.position.y;
CALayer *dotTwoLayer = _dotTwo.layer.presentationLayer;
_dotTwoX = dotTwoLayer.position.x;
_dotTwoY = dotTwoLayer.position.y;
[self updateShapeLayerPath];
}
@end
好了,今天就到这里,祝大家新年快乐😄
