iOS项目 画图小程序

 

 

 

 

两个重点 一个设置一个

CGMutablePathRef 来存放不断变动的线条

另一个

@property (nonatomic,strong)NSMutableArray *paths;

 用来存放已经画好的线条

 

代码如下

#import "DSNView.h"

#import "DSNPath.h"

 

@interface DSNView ()

@property (nonatomic,strong)NSMutableArray *paths;

@end

 

@implementation DSNView

{

    CGPoint point;

    CGMutablePathRef path;

}

 

 

-(NSMutableArray *)paths

{

 

    if (!_paths) {

        _paths = [NSMutableArray array];

    }

    return _paths;

}

 

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

    UITouch *touch = [touches anyObject];

    point = [touch locationInView:self];

    

    path = CGPathCreateMutable();

    CGPathMoveToPoint(path, NULL, point.x, point.y);

    

}

 

-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

    UITouch *touch = [touches anyObject];

    point = [touch locationInView:self];

    

    [self setNeedsDisplay];

 

}

 

-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

{

    DSNPath *mPath = [[DSNPath alloc]init];

    

    mPath.myPath = path;

    [self.paths addObject:mPath];

}

// Only override drawRect: if you perform custom drawing.

// An empty implementation adversely affects performance during animation.

- (void)drawRect:(CGRect)rect {

    CGContextRef context = UIGraphicsGetCurrentContext();

    

    CGPathAddLineToPoint(path, NULL, point.x, point.y);

    

    CGContextAddPath(context, path);

    

    CGContextStrokePath(context);

    for (int i = 0; i<self.paths.count; i++) {

        DSNPath *mPath = self.paths[i];

        

//        mPath.myPath = path;

        CGContextAddPath(context, mPath.myPath);

        CGContextStrokePath(context);

    }

}