CAGradientLayer的一些属性解析

来源：互联网发布：SQL是面向问题的语言吗编辑：程序博客网时间：2024/04/28 04:39

iOS中Layer的坐标系统:

效果:

- (void)viewDidLoad{    [super viewDidLoad];    CAGradientLayer *colorLayer = [CAGradientLayer layer];    colorLayer.frame    = (CGRect){CGPointZero, CGSizeMake(200, 200)};    colorLayer.position = self.view.center;    [self.view.layer addSublayer:colorLayer];    // 颜色分配    colorLayer.colors = @[(__bridge id)[UIColor redColor].CGColor,                          (__bridge id)[UIColor greenColor].CGColor,                          (__bridge id)[UIColor blueColor].CGColor];        // 颜色分割线    colorLayer.locations  = @[@(0.25), @(0.5), @(0.75)];        // 起始点    colorLayer.startPoint = CGPointMake(0, 0);        // 结束点    colorLayer.endPoint   = CGPointMake(1, 0);}

颜色分配严格遵守Layer的坐标系统,locations,startPoint,endPoint都是以Layer坐标系统进行计算的.

而locations并不是表示颜色值所在位置,它表示的是颜色在Layer坐标系相对位置处要开始进行渐变颜色了.

CAGradientLayer 的这四个属性 colors locations startPoint endPoint 都是可以进行动画的哦.

附录:

稍微复杂点的动画效果

////  RootViewController.m////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "RootViewController.h"#import "YXGCD.h"@interface RootViewController ()@property (nonatomic, strong) GCDTimer  *timer;@end@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];    CAGradientLayer *colorLayer = [CAGradientLayer layer];    colorLayer.backgroundColor = [UIColor blueColor].CGColor;    colorLayer.frame    = (CGRect){CGPointZero, CGSizeMake(200, 200)};    colorLayer.position = self.view.center;    [self.view.layer addSublayer:colorLayer];    // 颜色分配    colorLayer.colors = @[(__bridge id)[UIColor cyanColor].CGColor,                          (__bridge id)[UIColor orangeColor].CGColor,                          (__bridge id)[UIColor magentaColor].CGColor];        // 起始点    colorLayer.startPoint = CGPointMake(0, 0);        // 结束点    colorLayer.endPoint   = CGPointMake(1, 0);        _timer = [[GCDTimer alloc] initInQueue:[GCDQueue mainQueue]];    [_timer event:^{                static CGFloat test = - 0.1f;                if (test >= 1.1)        {            test = - 0.1f;            [CATransaction setDisableActions:YES];            colorLayer.locations  = @[@(test), @(test + 0.05), @(test + 0.1)];        }        else        {            [CATransaction setDisableActions:NO];            colorLayer.locations  = @[@(test), @(test + 0.05), @(test + 0.1)];        }                test += 0.1f;            } timeInterval:NSEC_PER_SEC];    [_timer start];}@end

    _timer = [[GCDTimer alloc] initInQueue:[GCDQueue mainQueue]];    [_timer event:^{                static CGFloat test = - 0.1f;                if (test >= 1.1)        {            test = - 0.1f;            [CATransaction setDisableActions:NO];            colorLayer.locations  = @[@(test), @(test + 0.01), @(test + 0.011)];        }        else        {            [CATransaction setDisableActions:NO];            colorLayer.locations  = @[@(test), @(test + 0.01), @(test + 0.011)];        }                test += 0.1f;            } timeInterval:NSEC_PER_SEC];    [_timer start];

配合CAShapeLayer使用

////  RootViewController.m////  Copyright (c) 2014年 Y.X. All rights reserved.//#import "RootViewController.h"#import "YXGCD.h"@interface RootViewController ()@property (nonatomic, strong) GCDTimer  *timer;@end// 将常数转换为度数#define   DEGREES(degrees)  ((M_PI * (degrees))/ 180.f)@implementation RootViewController- (void)viewDidLoad{    [super viewDidLoad];    self.view.backgroundColor = [UIColor blackColor];    CAGradientLayer *colorLayer = [CAGradientLayer layer];    colorLayer.backgroundColor = [UIColor blueColor].CGColor;    colorLayer.frame    = (CGRect){CGPointZero, CGSizeMake(200, 200)};    colorLayer.position = self.view.center;    [self.view.layer addSublayer:colorLayer];    // 颜色分配    colorLayer.colors = @[(__bridge id)[UIColor redColor].CGColor,                          (__bridge id)[UIColor whiteColor].CGColor,                          (__bridge id)[UIColor redColor].CGColor];    colorLayer.locations  = @[@(-0.2), @(-0.1), @(0)];        // 起始点    colorLayer.startPoint = CGPointMake(0, 0);        // 结束点    colorLayer.endPoint   = CGPointMake(1, 0);        CAShapeLayer *circle = [RootViewController LayerWithCircleCenter:CGPointMake(102, 100)                                                              radius:80                                                          startAngle:DEGREES(0)                                                            endAngle:DEGREES(360)                                                           clockwise:YES                                                     lineDashPattern:nil];    circle.strokeColor = [UIColor redColor].CGColor;    [self.view.layer addSublayer:circle];    circle.strokeEnd = 1.f;    colorLayer.mask = circle;        _timer = [[GCDTimer alloc] initInQueue:[GCDQueue mainQueue]];    [_timer event:^{        static int i = 0;        if (i++ % 2 == 0)        {            CABasicAnimation* fadeAnim = [CABasicAnimation animationWithKeyPath:@"locations"];            fadeAnim.fromValue = @[@(-0.2), @(-0.1), @(0)];            fadeAnim.toValue   = @[@(1.0), @(1.1), @(1.2)];            fadeAnim.duration  = 1.5;            [colorLayer addAnimation:fadeAnim forKey:nil];        }    } timeInterval:NSEC_PER_SEC];    [_timer start];}+ (CAShapeLayer *)LayerWithCircleCenter:(CGPoint)point                                 radius:(CGFloat)radius                             startAngle:(CGFloat)startAngle                               endAngle:(CGFloat)endAngle                              clockwise:(BOOL)clockwise                        lineDashPattern:(NSArray *)lineDashPattern{    CAShapeLayer *layer = [CAShapeLayer layer];        // 贝塞尔曲线(创建一个圆)    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(0, 0)                                                        radius:radius                                                    startAngle:startAngle                                                      endAngle:endAngle                                                     clockwise:clockwise];        // 获取path    layer.path = path.CGPath;    layer.position = point;        // 设置填充颜色为透明    layer.fillColor = [UIColor clearColor].CGColor;        // 获取曲线分段的方式    if (lineDashPattern)    {        layer.lineDashPattern = lineDashPattern;    }        return layer;}@end

1 0