微不足道的图片浏览器

　　因为项目需要对图片进行浏览，而网上一些好的图片浏览框架使用起来比较麻烦，而且需要的代码量较大，于是自行封装了一个图片浏览器。在使用方面我会用一个例子进行说明，而图片浏览的背景可以自定义与该图片浏览器没有关系。个人觉得使用比较方便简单，如果在使用的过程中遇到bug，可以联系1152650004，一起探讨。

　　首先是进度条，用来显示图片加载的进度，代码如下：

//
//  LMFProgressView.m
//  LiPu
//
//  Created by wantexe on 16/7/5.
//  Copyright © 2016年 limingfeng. All rights reserved.
//

#import "LMFProgressView.h"
#import <QuartzCore/QuartzCore.h>

@interface LMFProgressView ()
@property (nonatomic, strong) UILabel *myLabel;
@end

@implementation LMFProgressView

- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame])
    {
        self.backgroundColor = [UIColor clearColor];
        self.myLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 20)];
        self.myLabel.textColor = [UIColor whiteColor];
        self.myLabel.textAlignment = NSTextAlignmentCenter;
        self.myLabel.backgroundColor = [UIColor clearColor];
        self.myLabel.center = self.center;
        self.myLabel.font = [UIFont systemFontOfSize:12];
        [self addSubview:self.myLabel];
    }
    return self;
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // 生产出一个圆的路径 -M_PI_2 -M_PI_2+angle*M_PI*2
    CGPoint circleCenter = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));
    CGFloat circleRadius = self.bounds.size.width/2.0;
    double angle = 1.4;
    if (angle>2) {
        angle-=2;
    }else if (angle>1){
        angle-=1;
    }
    UIBezierPath *circlePath = [UIBezierPath bezierPathWithArcCenter:circleCenter
                                                              radius:circleRadius
                                                          startAngle:-M_PI_2
                                                            endAngle:-M_PI_2+2*M_PI*self.progress
                                                           clockwise:YES];
    
    // 生产出一个圆形路径的Layer
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.path = circlePath.CGPath;
    shapeLayer.strokeColor = [UIColor whiteColor].CGColor;
    shapeLayer.fillColor = [[UIColor clearColor] CGColor];
    shapeLayer.lineWidth = 1;
    //    shapeLayer.lineCap = @"round";
    
    // 可以设置出圆的完整性
    shapeLayer.strokeStart = 0;
    shapeLayer.strokeEnd = self.progress;
    [self.layer addSublayer:shapeLayer];
    
}

- (void)setProgress:(CGFloat)progress
{
    _progress = progress;
    NSString *text = [NSString stringWithFormat:@"%li%@", (NSInteger)(self.progress*100), @"%"];
    self.myLabel.text = text;
    /*
     setNeedsDisplay会调用自动调用drawRect方法，这样可以拿到  UIGraphicsGetCurrentContext，就可以画画了。而setNeedsLayout会默认调用layoutSubViews，
     */
    [self setNeedsDisplay];
    if (self.progress >= 1)
    {
        [self removeFromSuperview];
    }
}

@end

　　接下来是对图片处理的核心代码，主要添加了单击返回事件，双击放大缩小事件，两根手指放大缩小事件，代码如下：

//
//  LMFImageView.m
//  LiPu
//
//  Created by wantexe on 16/7/4.
//  Copyright © 2016年 limingfeng. All rights reserved.
//
/*
 最多放大为原图的2倍，超过时要自动缩小；最小缩小为原图的一半
 */
#define LMFBIGRATE 2
#define LMFSMALLRATE 0.5
#define SCREENW [UIScreen mainScreen].bounds.size.width
#define SCREENH [UIScreen mainScreen].bounds.size.height
#import "LMFImageView.h"
#import "UIImageView+WebCache.h"
@interface LMFImageView ()
{
    NSInteger gestureTimes;
    CGRect oringinalFrame;
    float _totalScale;
    LMFProgressView *lmfProgressView;
}
@end

@implementation LMFImageView

- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame])
    {
        self.userInteractionEnabled = YES;
        self.multipleTouchEnabled = YES;
        self.layer.masksToBounds = YES;
//        self.backgroundColor = [UIColor yellowColor];
        gestureTimes = 0;
        _totalScale = 1;
        self.imageView = [[UIImageView alloc] init];
        self.imageView.center = CGPointMake(SCREENW*0.5, SCREENH*0.5);
        oringinalFrame = self.imageView.frame;
        [self addSubview:self.imageView];
        
        lmfProgressView = [[LMFProgressView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
        lmfProgressView.center = CGPointMake(SCREENW*0.5, SCREENH*0.5);
        [self addSubview:lmfProgressView];
    }
    return self;
}

#pragma mark --设置图片地址
- (void)setPictureUrl:(NSString *)url andDefaultPicture:(NSString *)picture
{
    __weak typeof(lmfProgressView)weakProgress = lmfProgressView;
    [self.imageView sd_setImageWithURL:[NSURL URLWithString:url] placeholderImage:[UIImage imageNamed:picture] options:SDWebImageRetryFailed progress:^(NSInteger receivedSize, NSInteger expectedSize) {
        weakProgress.progress = (CGFloat)receivedSize/(CGFloat)expectedSize;
        NSLog(@"%f", weakProgress.progress);
    } completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
        if (error)
        {
            NSLog(@"图片加载失败");
            [weakProgress removeFromSuperview];
        }
        if (error.description == nil)
        {
            float width = SCREEN_WIDTH;
            float height = width*image.size.height/image.size.width;
            self.imageView.frame = CGRectMake(0, 0, width, height);
            self.imageView.center = CGPointMake(SCREEN_WIDTH*0.5+10, SCREEN_HEIGHT*0.5);
            [weakProgress removeFromSuperview];
        }
    }];
}

#pragma mark --否添加两根手指放大缩小的手势
- (void)addPinGesture
{
    UIPinchGestureRecognizer *pin = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(zoomImage:)];
    [self addGestureRecognizer:pin];
}
#pragma mark --用两根手指来改变图片大小
- (void)changeFrame:(UIPinchGestureRecognizer *)gesture
{
    CGFloat scale = gesture.scale;
    CGFloat temp = _totalScale + (scale - 1);
    [self setTotalScale:temp];
    gesture.scale = 1.0;
}
- (void)zoomImage:(UIPinchGestureRecognizer *)recognizer
{
    CGFloat scale = recognizer.scale;
    CGFloat temp = _totalScale + (scale - 1);
    
    [self setTotalScale:temp];
    recognizer.scale = 1.0;
}

- (void)setTotalScale:(CGFloat)totalScale
{
    if ((_totalScale < 0.5 && totalScale < _totalScale) || (_totalScale > 3.0 && totalScale > _totalScale)) return; // 最大缩放 2倍,最小0.5倍
    
    [self zoomWithScale:totalScale];
}

- (void)zoomWithScale:(CGFloat)scale
{
    _totalScale = scale;
    self.imageView.transform = CGAffineTransformMakeScale(scale, scale);
    
    CGRect rect = self.imageView.frame;
    if (scale > 1)
    {
        rect.origin.x = 10;
    }
    else
    {
        rect.origin.x = (SCREEN_WIDTH-rect.size.width)/2.0+10;
    }
    self.imageView.frame = rect;
    [self setContentSize:CGSizeMake(self.imageView.frame.size.width, self.imageView.frame.size.height)];

}
#pragma mark --将图片变回到原图大小
- (void)changeFrameToOringinal
{
    //变回原图
    [UIView animateWithDuration:0.3 animations:^{
        self.imageView.frame = oringinalFrame;
        self.imageView.center = CGPointMake(SCREENW*0.5, SCREENH*0.5);
    }];
}
#pragma mark --变回原图的2倍大小
- (void)changeframeToTwoTimes
{
    CGRect frame = self.frame;
    //变大两倍
    frame.size = CGSizeMake(frame.size.width*LMFBIGRATE, frame.size.height*LMFBIGRATE);
    [UIView animateWithDuration:0.3 animations:^{
        self.imageView.frame = frame;
        self.imageView.center = CGPointMake(SCREENW*0.5, SCREENH*0.5);
    }];
}

#pragma mark --添加单击双击手势
- (void)addSingleAndDoubleGesture
{
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismiss:)];
    tap.numberOfTapsRequired = 1;
//    [self addGestureRecognizer:tap];
    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(bigImage:)];
    doubleTap.numberOfTapsRequired = 2;
    [self addGestureRecognizer:doubleTap];
    [tap requireGestureRecognizerToFail:doubleTap];
}
#pragma mark --单击手势
- (void)dismiss:(UITapGestureRecognizer *)gesture
{
    self.block();
}
#pragma mark --双击手势
- (void)bigImage:(UITapGestureRecognizer *)gesture
{
    CGRect frame = self.imageView.frame;
    if (gestureTimes%2 == 0)
    {
        //变大两倍
        frame.size = CGSizeMake(frame.size.width*LMFBIGRATE, frame.size.height*LMFBIGRATE);
        [UIView animateWithDuration:0.3 animations:^{
            self.imageView.frame = frame;
            self.imageView.center = CGPointMake(SCREENW*0.5, SCREENH*0.5);
        }];
    }
    else
    {
        //变回原图
        [self changeFrameToOringinal];
    }
    gestureTimes++;
}
#pragma mark --隐藏加载条
- (void)hiddenProgress
{
    lmfProgressView.hidden = YES;
}

@end

　　

//
//  LMFImageView.h
//  LiPu
//
//  Created by wantexe on 16/7/4.
//  Copyright © 2016年 limingfeng. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "LMFProgressView.h"
typedef void(^dismissBlock)();
typedef void(^bigFrameBlock)(CGRect);

@interface LMFImageView : UIScrollView

@property (nonatomic, copy) dismissBlock block;
@property (nonatomic, copy) bigFrameBlock bigFrameBlock;
@property (nonatomic, strong) UIImageView *imageView;
#pragma mark --否添加两根手指放大缩小的手势
- (void)addPinGesture;
#pragma mark --将图片变回到原图大小
- (void)changeFrameToOringinal;
#pragma mark --添加单击双击手势
- (void)addSingleAndDoubleGesture;
#pragma mark --设置图片地址
- (void)setPictureUrl:(NSString *)url andDefaultPicture:(NSString *)picture;
#pragma mark --隐藏加载条
- (void)hiddenProgress;
@end