本demo只实现基础画板涂鸦功能，撤销清屏功能，其余为空。demo框架如下:
#import <Foundation/Foundation.h>
@interface CustomModel : NSObject
// 中心点横坐标
@property (nonatomic,assign) float px;
// 中心点纵坐标
@property (nonatomic,assign) float py;
@end
// Copyright © 2017年 坏先森. All rights reserved.
//
#define BUTTON_TAG 1000
#import "CustomView.h"
#import "CustomModel.h"
@interface CustomView () {
float _pointX;
float _pointY;
NSMutableArray *_dataArray; // 每次开始触摸时候，存放的一组点
NSMutableArray *_totalArray; // 所有点的数组
}
@end
@implementation CustomView
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
_totalArray = [NSMutableArray array];
[self creatUI];
}
return self;
}
- (void)creatUI {
for (NSInteger i = 0; i<2; i++) {
UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
[button setTitle:i == 0 ? @"清空" : @"撤销" forState:UIControlStateNormal];
[button setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
button.backgroundColor = [UIColor yellowColor];
button.frame = CGRectMake(20+(80+self.frame.size.width-160-40)*(i%2), self.frame.size.height-50, 80, 40);
button.tag = BUTTON_TAG + i;
[button addTarget:self action:@selector(changePic:) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:button];
}
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// 设置颜色宽度等
CGContextRef ref = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(ref, 0.5, 0.5,0.5, 1);
CGContextSetLineWidth(ref, 2);
for (NSInteger i = 0; i<_totalArray.count+1; i++) {
if (i == _totalArray.count) {
// 当前正在触摸，滑动的部分
// 这样处理
// 找到起始点，数组里面的第一个元素
CustomModel *lastFirst = [_dataArray firstObject];
CGContextMoveToPoint(ref, lastFirst.px, lastFirst.py);
[self customSetLineWith:ref withArray:_dataArray];
}else {
// 滑动的历史
NSArray *data = [_totalArray objectAtIndex:i];
CustomModel *first = [data objectAtIndex:0];
CGContextMoveToPoint(ref, first.px, first.py);
[self customSetLineWith:ref withArray:data];
}
}
CGContextStrokePath(ref);
}
- (void)customSetLineWith:(CGContextRef)ref withArray:(NSArray *)data{
for (NSInteger j = 0; j<data.count; j++) {
CustomModel *contentModel = [data objectAtIndex:j];
CGContextAddLineToPoint(ref, contentModel.px, contentModel.py);
}
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
_dataArray = [NSMutableArray arrayWithCapacity:0];
[self customGetThePointWithTouches:touches];
}
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
[self customGetThePointWithTouches:touches];
[self setNeedsDisplay];
}
- (void)customGetThePointWithTouches:(NSSet<UITouch *> *)touches {
UITouch *touch = [touches anyObject];
CGPoint point = [touch locationInView:self];
CustomModel *model = [[CustomModel alloc] init];
model.px = point.x;
model.py = point.y;
[_dataArray addObject:model];
}
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
[_totalArray addObject:_dataArray];
}
- (void)changePic:(UIButton *)sender {
[_dataArray removeAllObjects];
switch (sender.tag) {
case BUTTON_TAG:
[_totalArray removeAllObjects];
break;
case BUTTON_TAG+1:
[_totalArray removeLastObject];
break;
default:
break;
}
[self setNeedsDisplay];
}
@end
// Copyright © 2017年 坏先森. All rights reserved.
//
#import "ViewController.h"
#import "CustomView.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self creatView];
}
#pragma mark - 方法
- (void)creatView {
CustomView *view = [[CustomView alloc] initWithFrame:self.view.frame];
view.backgroundColor = [UIColor cyanColor];
[self.view addSubview:view];
}
到此结束
