iOS之Scanning的实现
http://i.cnblogs.com/EditPosts.aspx?postid=5288517
//写在最前
/*
AVFoundation原生框架的好处就是扫描特别快效率特别高，但是可能会遇到一个问题就是不知道怎么去限制扫描范围。
二维码扫描有关优秀第三方库:---- ZXing google推出的开源项目-----ZBar SDK 里面也有详细的文档
*/
引入头文件导入流媒体需要的框架
@import AVFoundation;
//遵守协议 AVCaptureMetadataOutputObjectsDelegate
@property (nonatomic,strong)AVCaptureSession *session;
@property (nonatomic,strong)AVCaptureVideoPreviewLayer *layer;
- (void)viewDidLoad {
[super viewDidLoad];
[self startRunningSession];
[self.view bringSubviewToFront:self.v];
self.animV = [[UIView alloc]initWithFrame:CGRectMake(92, 124, 190, 2)];
self.animV.backgroundColor = [UIColor redColor];
[self.view addSubview:self.animV];
if (!_t) {
self.t = [NSTimer scheduledTimerWithTimeInterval:4.2/24 target:self selector:@selector(animateShow) userInfo:nil repeats:YES];
}
}
- (void)animateShow{
CGRect frame = self.animV.frame;
frame.origin.y += 8;
if (frame.origin.y >= 316) {
frame.origin.y = 116;
}
self.animV.frame = frame;
}
- (void)startRunningSession
// 获取 AVCaptureDevice 实例
NSError * error;
AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
[captureDevice setTorchMode:AVCaptureTorchModeOn]; //开启照明
// 初始化输入流
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];
if (!input) {
NSLog(@"%@", [error localizedDescription]);
}
// 创建会话
_session = [[AVCaptureSession alloc] init];
if ([_session canAddInput:input]) {
// 添加输入流
[_session addInput:input];
}
// 初始化输出流
AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
if ([_session canAddOutput:captureMetadataOutput]) {
// 添加输出流
[_session addOutput:captureMetadataOutput];
}
// 创建dispatch queue.
dispatch_queue_t dispatchQueue;
dispatchQueue = dispatch_queue_create(kScanName, NULL);
[captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[captureMetadataOutput setRectOfInterest:CGRectMake(100/667.0,87/375.0,200/667.0, 200/375.0)];
// 设置元数据类型 AVMetadataObjectTypeQRCode
[captureMetadataOutput setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
//value CGRectMake(0, 0, 1, 1). Metadata objects whose bounds do not intersect with the rectOfInterest will not be returned.
// 创建输出对象
_layer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
[_layer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
[_layer setFrame:self.view.layer.frame];
[self.view.layer addSublayer:_layer];
// 开始会话
[_session startRunning];
}
#pragma - mark - AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
NSLog(@"-------");
if (metadataObjects && metadataObjects.count) {
AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];
NSString *result;
if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {
result = metadataObj.stringValue;
NSLog(@"result:%@",result);
} else {
NSLog(@"不是二维码");
}
[_session stopRunning];
_session = nil;
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"QRCodeInfo"
message:result
delegate:nil
cancelButtonTitle:@"cancel"
otherButtonTitles: nil];
[alert show];
}
}
#import "cornView.h"
@import CoreGraphics;
//给扫描控制器加一个View进行遮盖处理就是上面的self.v
- (void)drawRect:(CGRect)rect {
UIBezierPath *p = [UIBezierPath bezierPathWithRect:CGRectMake(87, 56, 200, 200)];
// NSLog(@"0000");
[[UIColor clearColor]setFill];
填充为中间没有颜色
[p fill];
填充之外的不烦
[p fillWithBlendMode:kCGBlendModeClear alpha:1];
}
//写在最后
很小的二维码,边长不到1cm，于是就修改了 sessionPreset 为 1080p 的，当时用的是ZXing, 当把图片质量改清楚时，也造成了性能的下降，基本打开扫描界面就会报memoryWarning，但是也确实解决了小二维码扫描的问题。
AVCaptureSession 可以设置 sessionPreset 属性，这个决定了视频输入每一帧图像质量的大小。
- AVCaptureSessionPreset320x240
- AVCaptureSessionPreset352x288
- AVCaptureSessionPreset640x480
- AVCaptureSessionPreset960x540
- AVCaptureSessionPreset1280x720
- AVCaptureSessionPreset1920x1080
以上列举了部分的属性值，分别代表输入图片质量大小，一般来说AVCaptureSessionPreset640x480就够使用，但是如果要保证较小的二维码图片能快速扫描，最好设置高些，如AVCaptureSessionPreset1920x1080(就是我们常说的1080p).
提升扫描速度和性能的就是设置解析的范围，在zbar和zxing中就是scanCrop, AVFoundation中设置 AVCaptureMetadataOutput 的 rectOfInterest 属性来配置解析范围。
captureOutput.rectOfInterest = CGRectMake(cropRect.origin.y/size.height, cropRect.origin.x/size.width, cropRect.size.height/size.height, cropRect.size.width/size.width);rectOfInterest是基于图像的大小裁剪的。
》》》此博文源于各路汇总。
