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iphone ios layer 教程应用

2013-02-02 10:53 531 查看
CALayer(层)是屏幕上的一个矩形区域,在每一个UIView中都包含一个根CALayer,在UIView上的所有视觉效果都是在这个Layer上进行的。

CALayer外形特征主要包括:

1、层的大小尺寸

2、背景色

3、内容(可以填充图片或者使用Core Graphics绘制的内容)

4、矩形是否使用圆角

5、矩形是否有阴影

Layer有很多种,最常用也是最基本的是CALayer,当然还包括其他的子类:

CAScrollerLayer 简化显示层的一部分

CATextLayer 文本层

CAGradientLayer、CAShapeLayer等等

使用层之前,需要在项目中引入QuartzCore.framework框架

实例:

新建XCode项目LayerSample,导入QuartzCore.famework





在LayerSampleViewController.h文件中引入:

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#import <QuartzCore/QuartzCore.h>

LayerSampleViewController.m文件,代码:

//

// LayerSampleViewController.m

// LayerSample

//

// Created by jordy on 11-3-28.

// Copyright 2011 vsp. All rights reserved.

//

#import "LayerSampleViewController.h"

@implementation LayerSampleViewController

// Implement loadView to create a view hierarchy programmatically, without using a nib.

- (void)loadView {

UIView *rootView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];

rootView.backgroundColor = [UIColor whiteColor];

self.view = rootView;

[rootView release];

//加载layer

backLayer = [CALayer layer];

backLayer.backgroundColor = [UIColor orangeColor].CGColor;

backLayer.bounds = CGRectMake(10, 10, 1004, 728); //设置layer的区域

backLayer.position = CGPointMake(1024/2, 768/2-10); //设置layer坐标

[self.view.layer addSublayer:backLayer];

}

// Override to allow orientations other than the default portrait orientation.

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {

return interfaceOrientation == UIInterfaceOrientationLandscapeLeft;

}

- (void)didReceiveMemoryWarning {

// Releases the view if it doesn't have a superview.

[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.

}

- (void)viewDidUnload {

// Release any retained subviews of the main view.

// e.g. self.myOutlet = nil;

}

- (void)dealloc {

[super dealloc];

}

@end

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#import <QuartzCore/QuartzCore.h>

LayerSampleViewController.m文件,代码:

//

// LayerSampleViewController.m

// LayerSample

//

// Created by jordy on 11-3-28.

// Copyright 2011 vsp. All rights reserved.

//

#import "LayerSampleViewController.h"

@implementation LayerSampleViewController

// Implement loadView to create a view hierarchy programmatically, without using a nib.

- (void)loadView {

UIView *rootView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1024, 768)];

rootView.backgroundColor = [UIColor whiteColor];

self.view = rootView;

[rootView release];

//加载layer

backLayer = [CALayer layer];

backLayer.backgroundColor = [UIColor orangeColor].CGColor;

backLayer.bounds = CGRectMake(10, 10, 1004, 728); //设置layer的区域

backLayer.position = CGPointMake(1024/2, 768/2-10); //设置layer坐标

[self.view.layer addSublayer:backLayer];

}

// Override to allow orientations other than the default portrait orientation.

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {

return interfaceOrientation == UIInterfaceOrientationLandscapeLeft;

}

- (void)didReceiveMemoryWarning {

// Releases the view if it doesn't have a superview.

[super didReceiveMemoryWarning];

// Release any cached data, images, etc that aren't in use.

}

- (void)viewDidUnload {

// Release any retained subviews of the main view.

// e.g. self.myOutlet = nil;

}

- (void)dealloc {

[super dealloc];

}

@end

运行程序:





为了区分背景UIView,我将UIView的背景色设置为白色,backLayer的背景色设置为橘黄色。

上图是一个矩形区域,如果设置矩形的四个角是椭圆角,可以添加属性:

backLayer.cornerRadius = 20.0; //矩形椭圆角的弧度半径

运行程序后,效果如图:





添加带阴影的子Layer(层),代码:

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//添加子layer

CALayer *cyanLayer = [CALayer layer];

cyanLayer.backgroundColor = [UIColor cyanColor].CGColor;

cyanLayer.bounds = CGRectMake(0, 0, 300, 300);

cyanLayer.position = CGPointMake(180, 180);

cyanLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量

cyanLayer.shadowRadius = 10.0; //设置阴影的半径

cyanLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

cyanLayer.shadowOpacity = 0.9; //设置阴影的不透明度

[backLayer addSublayer:cyanLayer];

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//添加子layer

CALayer *cyanLayer = [CALayer layer];

cyanLayer.backgroundColor = [UIColor cyanColor].CGColor;

cyanLayer.bounds = CGRectMake(0, 0, 300, 300);

cyanLayer.position = CGPointMake(180, 180);

cyanLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量

cyanLayer.shadowRadius = 10.0; //设置阴影的半径

cyanLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

cyanLayer.shadowOpacity = 0.9; //设置阴影的不透明度

[backLayer addSublayer:cyanLayer];

运行效果图:





给子Layer添加图片

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//添加子image layer

UIImage *image = [UIImage imageNamed:@"feiche.jpg"];

CALayer *imageLayer = [CALayer layer];

imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

imageLayer.contents = (id) image.CGImage;

imageLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量

imageLayer.shadowRadius = 10.0; //设置阴影的半径

imageLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

imageLayer.shadowOpacity = 0.9; //设置阴影的不透明度

[backLayer addSublayer:imageLayer];

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//添加子image layer

UIImage *image = [UIImage imageNamed:@"feiche.jpg"];

CALayer *imageLayer = [CALayer layer];

imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

imageLayer.contents = (id) image.CGImage;

imageLayer.shadowOffset = CGSizeMake(0, 3); //设置阴影的偏移量

imageLayer.shadowRadius = 10.0; //设置阴影的半径

imageLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

imageLayer.shadowOpacity = 0.9; //设置阴影的不透明度

[backLayer addSublayer:imageLayer];

运行效果,





图片加边框,代码:

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imageLayer.borderColor = [UIColor grayColor].CGColor; //边框颜色

imageLayer.borderWidth = 2.0; //边框宽度

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imageLayer.borderColor = [UIColor grayColor].CGColor; //边框颜色

imageLayer.borderWidth = 2.0; //边框宽度

运行效果:





设置图片为椭圆角,代码:

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imageLayer.cornerRadius = 10.0; //设置layer圆角半径

imageLayer.masksToBounds = YES; //隐藏边界

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imageLayer.cornerRadius = 10.0; //设置layer圆角半径

imageLayer.masksToBounds = YES; //隐藏边界

运行效果:





但是由于设置masksToBounds 属性为true所以Layer的阴影效果也就没有了。

之前我都是将图片另外在做有阴影效果的图片,这样显的比较真实,如果阴影部分只是填充边框即可,可以采用两个Layer来实现阴影效果,代码:

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UIImage *image = [UIImage imageNamed:@"feiche.jpg"];

//阴影layer

CALayer *shadowLayer = [CALayer layer];

shadowLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

shadowLayer.backgroundColor = [UIColor blueColor].CGColor;

shadowLayer.shadowOffset = CGSizeMake(0, 3);

shadowLayer.cornerRadius = 10.0;

shadowLayer.shadowRadius = 10.0;

shadowLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

shadowLayer.shadowOpacity = 1.0; //设置阴影的不透明度

[backLayer addSublayer:shadowLayer];

//添加子image layer

CALayer *imageLayer = [CALayer layer];

imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

imageLayer.contents = (id) image.CGImage;

imageLayer.cornerRadius = 10.0; //设置layer圆角半径

imageLayer.masksToBounds = YES; //隐藏边界

imageLayer.borderColor = [UIColor grayColor].CGColor; //边框颜色

imageLayer.borderWidth = 2.0;

[backLayer addSublayer:imageLayer];

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UIImage *image = [UIImage imageNamed:@"feiche.jpg"];

//阴影layer

CALayer *shadowLayer = [CALayer layer];

shadowLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

shadowLayer.backgroundColor = [UIColor blueColor].CGColor;

shadowLayer.shadowOffset = CGSizeMake(0, 3);

shadowLayer.cornerRadius = 10.0;

shadowLayer.shadowRadius = 10.0;

shadowLayer.shadowColor = [UIColor blackColor].CGColor; //设置阴影的颜色为黑色

shadowLayer.shadowOpacity = 1.0; //设置阴影的不透明度

[backLayer addSublayer:shadowLayer];

//添加子image layer

CALayer *imageLayer = [CALayer layer];

imageLayer.frame = CGRectMake(100, 100, image.size.width, image.size.height);

imageLayer.contents = (id) image.CGImage;

imageLayer.cornerRadius = 10.0; //设置layer圆角半径

imageLayer.masksToBounds = YES; //隐藏边界

imageLayer.borderColor = [UIColor grayColor].CGColor; //边框颜色

imageLayer.borderWidth = 2.0;

[backLayer addSublayer:imageLayer];

运行后效果:





------转自http://blog.csdn.net/linzhiji/article/details/6748207
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