iOS应用开发：小画板Demo

还有很多功能可以加，记在这里留着慢慢加吧。

代码部分

TouchView.h

#import <UIKit/UIKit.h>    

@interface TouchView : UIView
{
    NSMutableArray *points;
    NSArray *points_all;
    CGContextRef context;
    UIColor *paint_clr;
}
@property (strong,nonatomic) NSMutableArray *points;
@property (strong,nonatomic) NSArray *points_all;
@property (strong,nonatomic) UIColor *paint_clr;    

@end

TouchView.m

#import "TouchView.h"    

@implementation TouchView
@synthesize points, points_all, paint_clr;    

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        paint_clr = [UIColor greenColor];
    }
    return self;
}    

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
    if ((!self.points) || (self.points.count < 2)) {
        return;
    }    

    context = UIGraphicsGetCurrentContext();
    //设置画笔粗细
    CGContextSetLineWidth(context, 5.0f);
    //设置画笔颜色
    //[[UIColor blueColor]set ];
    // [paint_clr set];
    //CGContextSetStrokeColorWithColor(context, [[UIColor blueColor]CGColor]);
    CGContextSetStrokeColorWithColor(context, [paint_clr CGColor]);    

    //画以前的轨迹
    for (int j = 0 ; j < [self.points_all count]; j++) {
        NSMutableArray *points_tmp = [points_all objectAtIndex:j];    

            for (int i = 0;i < [points_tmp count]-1;i++)
            {
                CGPoint point1 = [[points_tmp objectAtIndex:i] CGPointValue];
                CGPoint point2 = [[points_tmp objectAtIndex:(i+1)] CGPointValue];
                CGContextMoveToPoint(context, point1.x, point1.y);
                CGContextAddLineToPoint(context, point2.x, point2.y);
                CGContextStrokePath(context);
            }
        }    

    //画这次
    for (int i=0; i < [self.points count]-1; i++) {
        CGPoint point1 = [[self.points objectAtIndex:i] CGPointValue];
        CGPoint point2 = [[self.points objectAtIndex:(i+1)] CGPointValue];
        CGContextMoveToPoint(context, point1.x, point1.y);
        CGContextAddLineToPoint(context, point2.x, point2.y);
        CGContextStrokePath(context);
    }
}    

//不支持多点触摸
- (BOOL) isMultipleTouchEnabled
{
    return NO;
}    

//创建一个array，并且记录初始ponit
- (void) touchesBegan:(NSSet *) touches withEvent:(UIEvent *) event
{
    self.points = [NSMutableArray array];
    CGPoint pt = [[touches anyObject] locationInView:self];
    [self.points addObject:[NSValue valueWithCGPoint:pt]];
}    

//移动过程中记录这些points
//调用setNeedsDisplay，会触发drawRect方法的调用
- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    CGPoint pt = [[touches anyObject] locationInView:self];
    [self.points addObject:[NSValue valueWithCGPoint:pt]];
    [self setNeedsDisplay];
}    

- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSMutableArray *points_tmp = [[NSMutableArray alloc] initWithArray:self.points];
    if (self.points_all == nil) {
        self.points_all = [[NSArray alloc] initWithObjects:points_tmp, nil];
    }else {
        self.points_all = [self.points_all arrayByAddingObject:points_tmp];
    }
}
@end

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