QuartZ2D __ 简单用法 1

一. 简单做一个画板

1. 建立一个UIView类

2. 在.m里建立一个延展

3. 分别定义一个起点, 一个终点的结构体属性 . 在建立一个存储路径的数组

@interface DrawView ()
{
    CGPoint _startPoint;
    CGPoint _endPoint;
}

@property (nonatomic, strong) NSMutableArray *pathArray;

@end

4. 懒加载数组

- (NSMutableArray *)pathArray
{
    if (_pathArray == nil) {
        _pathArray = [NSMutableArray array];
    }
    return _pathArray;
}

5. 开始绘制

(1) 起点

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    // 获取起点
    _startPoint = [[touches anyObject] locationInView:self];

    // 创建贝瑟尔路径
    UIBezierPath *path = [UIBezierPath bezierPath];
    // 起点
    [path moveToPoint:_startPoint];

    // 添加到数组中
    [self.pathArray addObject:path];

}

(2) 终点

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    _endPoint = [[touches anyObject] locationInView:self];

    // 终点
    UIBezierPath *path = [self.pathArray lastObject];

    [path addLineToPoint:_endPoint];

    [self setNeedsDisplay];
}

6. 重写  - (void)drawRect:(CGRect)rect 方法

- (void)drawRect:(CGRect)rect {
    // Drawing code

    for (UIBezierPath *path in self.pathArray) {
        // 设置颜色
        [[UIColor orangeColor] set];
        // 设置粗度
        path.lineWidth = 10;
        // 渲染
        [path stroke];
    }

}

二. 绘制饼状图

注 : 为了好看, 我随即分成了大小颜色都不同的99份

代码实现

#import "DrawView.h"

#define kcolor arc4random()% 256 / 255.0

@implementation DrawView

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code

    NSMutableArray *array = [NSMutableArray array];
    int sum = 0;
    for (int i = 1; i< 100; i ++) {
        int num = arc4random()% 100 ;
        sum += num;
        NSNumber *number = [NSNumber numberWithInt:num];
        [array addObject:number];
    }
    // 记录起点和终点
    CGFloat start = 0;
    CGFloat end = 0;
    // 遍历数据
    for (NSNumber *num in array) {

        end = num.floatValue / sum * M_PI * 2;

        UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(150, 150) radius:100 startAngle:start endAngle:start + end clockwise:YES];
        // 关闭路径
        [path addLineToPoint:CGPointMake(150, 150)];

        [[UIColor colorWithRed:kcolor green:kcolor blue:kcolor alpha:1] set];
        [path closePath];
        [path fill];
        start += end;

    }

@end

三. 截图用法

1. 首先要有一个imageView, 所以在ViewContorller先建立一个UIImageView的属性 将背景的图片设置出来

2. 建立一个继承自UIView的类

3. 在这个UIView类.m里实现截图 (.h中写了一个block块用于传递路径)

.h 代码实现

// 传递路径
typedef void(^block)(UIBezierPath *p);

@interface MyView : UIView

@property (nonatomic, copy) block myblock;

@end

.m 代码实现

#import "MyView.h"

@interface MyView ()

// 保存路径
@property (nonatomic, strong) NSMutableArray *pathArray;

@end

@implementation MyView

- (NSMutableArray *)pathArray
{
    if (! _pathArray) {
        _pathArray = [NSMutableArray array];
    }
    return _pathArray;
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    // 1. 获取起始点 并且创建路径
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:[[touches anyObject] locationInView:self]];

    // 2. 装入数组
    [self.pathArray addObject:path];

}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    // 1. 获取终点 (不止一个)
    UIBezierPath *path = [self.pathArray lastObject];
    [path addLineToPoint:[[touches anyObject] locationInView:self]];

    // 2. 调用drawrect
    [self setNeedsDisplay];

}

- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    // 封闭路径
    UIBezierPath *path = [self.pathArray lastObject];
    [path closePath];

    [self setNeedsDisplay];
    // 调用block路径
    self.myblock(path);
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
    for (UIBezierPath *path in self.pathArray) {
        path.lineWidth = 2;
        [[UIColor orangeColor] set];
        [path stroke];

    }
}

@end

4. 在ViewController中中回调路径

#import "ViewController.h"

#import "MyImageView.h"

#import "MyView.h"

@interface ViewController ()

@property (nonatomic, strong) UIImageView *imageView;

@property (nonatomic, strong) MyView *myView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // 获取图片
    // __block全局区
   __block UIImage *image = [UIImage imageNamed:@"0"];
    self.imageView = [[UIImageView alloc] initWithImage:image];
    _imageView.frame = CGRectMake(7, 160, image.size.width, image.size.height);
    [self.view addSubview: _imageView];

    self.myView = [[MyView alloc] initWithFrame:self.imageView.frame];
    _myView.backgroundColor = [UIColor colorWithRed:1 green:1 blue:1 alpha:0];
    [self.view addSubview:_myView];

    // 剪切

    __weak typeof(self) weakSelf = self;
    _myView.myblock = ^(UIBezierPath *p){

        // 获取上下文
        UIGraphicsBeginImageContextWithOptions(image.size, NO, 0);
        // 路径
        UIBezierPath *path = p;
        // 剪切
        [path addClip];
        // 绘制
        [image drawAtPoint:CGPointZero];
        // 获取剪切后的图片
        image = UIGraphicsGetImageFromCurrentImageContext();
        // 结束上下文
        UIGraphicsEndImageContext();
        // 给imageView赋值
        weakSelf.imageView.image = image;

    };
}

@end