iOS 原生扫描rectOfInterest扫描区域详解

rectOfInterest官方定义:

The value of this property is a CGRect that determines the receiver's rectangle of interest for each frame of video. The rectangle's origin is top left and is relative to the coordinate space of the device providing the metadata. Specifying a rectOfInterest may improve detection performance for certain types of metadata. The default value of this property is the value CGRectMake(0, 0, 1, 1). Metadata objects whose bounds do not intersect with the rectOfInterest will not be returned.

大致意思是设置每一帧画面感兴趣的区域     也就是扫描范围的设置  默认为左上角  (0,0,1,1)这是默认值  全屏的 最大为1

经实践发现  (0,0,,1,1)这个写法有点坑   实际为(y,x,h,w)  即坐标y,x  尺寸高,宽(h,w)

下面代码是我设置的扫描区域

 CGSize size = self.view.bounds.size;
    CGRect cropRect = CGRectMake(SCREEN_WIDTH/2-110,100,220,220);
    output.rectOfInterest =  CGRectMake(cropRect.origin.y/SCREEN_HEIGHT,
                                        cropRect.origin.x/size.width,
                                        cropRect.size.height/size.height,
                                        cropRect.size.width/size.width);

size是我的扫描区域  也就是那个扫描框框  再进行 rectOfInterest   那么能够进行识别 码   的区域也局限于框框内部   

下面是我的全部扫描代码

//
//  ScanViewController.m
//
//
//  Created by lxy on 2017/4/28.
//  Copyright © 2017年 xxx  All rights reserved.
//

#import "ScanViewController.h"
#import <AVFoundation/AVFoundation.h>

#define SCREEN_WIDTH [UIScreen mainScreen].bounds.size.width
#define SCREEN_HEIGHT [UIScreen mainScreen].bounds.size.height
#define RGB(r, g, b)                        [UIColor colorWithRed:(r)/255.f green:(g)/255.f blue:(b)/255.f alpha:1.f]
#define lxy(x, y, w, h)                    CGRectMake(x, y, w, h)

@interface ScanViewController ()<AVCaptureMetadataOutputObjectsDelegate>

@property (nonatomic, strong) AVCaptureSession *session;
@end

@implementation ScanViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.view.userInteractionEnabled = YES;
    
    
    
    [self initUII];
    [self setupCamera];
}

- (void)initUII{
    
    //    (SCREEN_WIDTH-220)/2+220;
    //左侧的view
    UIImageView *leftView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH/2-110, SCREEN_HEIGHT)];
    leftView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.7];
    [self.view addSubview:leftView];
    
    //右侧的view
    UIImageView *rightView = [[UIImageView alloc] initWithFrame:CGRectMake(SCREEN_WIDTH/2+110, 0, SCREEN_WIDTH/2-110, SCREEN_HEIGHT)];
    rightView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.7];
    [self.view addSubview:rightView];
    
    //最上部view
    UIImageView* upView = [[UIImageView alloc] initWithFrame:CGRectMake(SCREEN_WIDTH/2-110, 0, 220, 100)];
    upView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.7];
    [self.view addSubview:upView];
    
    //底部view
    UIImageView * downView = [[UIImageView alloc] initWithFrame:CGRectMake(SCREEN_WIDTH/2-110, 100+220, 220, SCREEN_HEIGHT-220-100)];
    downView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.7];
    
    [self.view addSubview:downView];
    
    
    
    
    
    
}

- (void)setupCamera
{
    //获取摄像设备
    AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    //创建输入流
    AVCaptureDeviceInput * input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
    if (!input) return;
    //创建输出流
    AVCaptureMetadataOutput * output = [[AVCaptureMetadataOutput alloc]init];
    
    
    //扫描区域控制
    //    AVCaptureMetadataOutput 中的属性rectOfInterest 看起来是CGRect类型, 填写一个比例。加入屏幕的frame 为 x , y, w, h, 要设置的矩形快的frame 为 x1, y1, w1, h1. 那么rectOfInterest 应该设置为 CGRectMake(y1/y, x1/x, h1/h, w1/w)。
    CGSize size = self.view.bounds.size;
    CGRect cropRect = CGRectMake(SCREEN_WIDTH/2-110,100,220,220);
    output.rectOfInterest =  CGRectMake(cropRect.origin.y/SCREEN_HEIGHT,
                                        cropRect.origin.x/size.width,
                                        cropRect.size.height/size.height,
                                        cropRect.size.width/size.width);
    
    
    
    
    
    
    //设置代理 在主线程里刷新
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    
    //初始化链接对象
    _session = [[AVCaptureSession alloc]init];
    //高质量采集率
    [_session setSessionPreset:AVCaptureSessionPresetHigh];
    
    [_session addInput:input];
    [_session addOutput:output];
    //设置扫码支持的编码格式
    //    output.metadataObjectTypes =@[AVMetadataObjectTypeUPCECode, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode39Mod43Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeCode128Code, AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeAztecCode];
    output.metadataObjectTypes = @[AVMetadataObjectTypeQRCode,
                                   AVMetadataObjectTypeEAN13Code,
                                   AVMetadataObjectTypeEAN8Code,
                                   AVMetadataObjectTypeCode128Code];
    
    AVCaptureVideoPreviewLayer * layer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    layer.videoGravity=AVLayerVideoGravityResizeAspectFill;
    layer.frame=self.view.layer.bounds;
    [self.view.layer insertSublayer:layer atIndex:0];
    //开始捕获
    [_session startRunning];
}
#pragma mark AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    
    NSString *stringValue;
    if ([metadataObjects count] >0)
    {
        AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex:0];
        stringValue = metadataObject.stringValue;
        
        NSLog(@"--%@",stringValue);
    }
    
    
//    if ([metadataObjects count] >0)
//    {
//        [[[SoundModel alloc]init] getRightSound];
//        AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex:0];
//        stringValue = metadataObject.stringValue;
//        if (self.delegate && [self.delegate respondsToSelector:@selector(oddNumber:)]) {
//            [self.delegate oddNumber:stringValue];
//        }
//        
//    }
//    
//    if (!isSweep) {
//        [timer invalidate];
//        [_session stopRunning];
//        [self disMiss];
//    }
}

@end