记录一次Quartz2D学习(七)

(六)内主要讲述了图片的裁剪

本次主要讲交互

7.交互

　　7.1  通过外部刷新内部的显示效果

　　　　初始化的时候设定好初始值,调用setNeedsDisplay方法来重新绘制

- (instancetype)init

{

self = [super init];

if (self) {

self.backgroundColor = [UIColor whiteColor];

}

return self;

}

- (instancetype)initWithFrame:(CGRect)frame

{

self = [super initWithFrame:frame];

if (self) {

NSLog(@"initWithFrame");

self.radius = 1 ;

self.backgroundColor = [UIColor whiteColor];

}

return self;

}

-(void)setRadius:(float)radius{

_radius = radius*100;

[self setNeedsDisplay];

}

- (void)drawRect:(CGRect)rect {

NSLog(@"drawRect:%f",self.radius);

CGContextRef  ctx = UIGraphicsGetCurrentContext();

[[UIColor grayColor] set];

CGContextAddArc(ctx, 150, 150, self.radius, 0, M_PI*2, 0);

CGContextFillPath(ctx);

}

7.2使用runLoop进行逐帧播放的动画

- (instancetype)initWithFrame:(CGRect)frame

{

self = [super initWithFrame:frame];

if (self) {

self.backgroundColor = [UIColor whiteColor];

self.img_y=0;

//初始化时间管理器

CADisplayLink *  displayer =[CADisplayLink displayLinkWithTarget:self selector:@selector(upDateImage)];

//添加时间管理器到runLoop

[displayer addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];

}

return self;

}

-(void)upDateImage{

[self setNeedsDisplay];

}

- (void)drawRect:(CGRect)rect {

//位移量

self.img_y +=5;

//防止越界

if (self.img_y > [UIScreen mainScreen].bounds.size.height) {

self.img_y = 0;

}

//可有可无

CGContextRef  ctx = UIGraphicsGetCurrentContext();

//图片加载

UIImage * img =[UIImage imageNamed:@"图标-首页"];

//图片绘制到对应点

[img drawAtPoint:CGPointMake(0, self.img_y)];

}