我正在尝试为我正在使用的App设计条形码扫描仪。我希望扫描仪预览能够填满设备的整个屏幕,并提供一个较小的框架来指向条形码。所有的工作都是我想要的,但我不能让感兴趣的框架工作。
以下是条形码扫描仪的实施:
#import "GEScannerViewController.h"
@import AVFoundation;
@interface GEScannerViewController () <AVCaptureMetadataOutputObjectsDelegate> {
AVCaptureSession *_session;
AVCaptureDevice *_device;
AVCaptureDeviceInput *_input;
AVCaptureMetadataOutput *_output;
AVCaptureVideoPreviewLayer *_prevLayer;
UIView *_greyView;
UIView *_highlightView;
UIView *_scopeView;
UILabel *_label;
}
@end
@implementation GEScannerViewController
- (void)viewDidLoad {
[super viewDidLoad];
_label = [[UILabel alloc] init];
_label.frame = CGRectMake(0, self.view.bounds.size.height - 40, self.view.bounds.size.width, 40);
_label.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;
_label.backgroundColor = [UIColor colorWithWhite:0.15 alpha:0.65];
_label.textColor = [UIColor whiteColor];
_label.textAlignment = NSTextAlignmentCenter;
_label.text = @"(none)";
[self.view addSubview:_label];
NSError *error = nil;
_session = [[AVCaptureSession alloc] init];
_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
[_device lockForConfiguration:&error];
if (error) {
NSLog(@"Error: %@", error);
}
_device.focusPointOfInterest = CGPointMake(self.view.frame.size.width / 2, (self.view.frame.size.height / 2) - 80);
_input = [AVCaptureDeviceInput deviceInputWithDevice:_device error:&error];
if (_input) {
[_session addInput:_input];
} else {
NSLog(@"Error: %@", error);
}
_output = [[AVCaptureMetadataOutput alloc] init];
[_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
_output.rectOfInterest = CGRectMake((self.view.frame.size.width / 2) - 160, (self.view.frame.size.height / 2) - 160, 320, 160);
[_session addOutput:_output];
_output.metadataObjectTypes = [_output availableMetadataObjectTypes];
_prevLayer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
_prevLayer.frame = self.view.bounds;
_prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer:_prevLayer];
_greyView = [[UIView alloc] initWithFrame:self.view.frame];
_greyView.bounds = self.view.bounds;
_greyView.backgroundColor = [UIColor colorWithWhite:0.15 alpha:0.65];
[self.view.layer addSublayer:_greyView.layer];
_scopeView = [[UIView alloc] initWithFrame:CGRectMake((self.view.frame.size.width / 2) - 160, (self.view.frame.size.height / 2) - 160, 320, 160)];
_scopeView.backgroundColor = [UIColor clearColor];
_scopeView.layer.borderColor = [UIColor greenColor].CGColor;
_scopeView.layer.borderWidth = 1;
_scopeView.clipsToBounds = YES;
[self.view addSubview:_scopeView];
_highlightView = [[UIView alloc] init];
_highlightView.autoresizingMask = UIViewAutoresizingFlexibleTopMargin|UIViewAutoresizingFlexibleLeftMargin|UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleBottomMargin;
_highlightView.layer.borderColor = [UIColor greenColor].CGColor;
_highlightView.layer.borderWidth = 3;
[_scopeView addSubview:_highlightView];
[_session startRunning];
[self.view bringSubviewToFront:_highlightView];
[self.view bringSubviewToFront:_label];
}
我使用_output.rectOfInterest指定框架与_scopeView的框架相同。不幸的是,这不起作用。如果我这样做,就不会再识别条形码。
答案 0 :(得分:7)
我一收到,就绝对清楚了:
AVCaptureMetadataOutput由像素定义,因此要将显示的坐标映射到输出中的坐标,我必须使用metadataOutputRectOfInterestForRect:
From AVCaptureOutput.h:
/*!
@method metadataOutputRectOfInterestForRect:
@abstract
Converts a rectangle in the receiver's coordinate space to a rectangle of interest in the coordinate space of an AVCaptureMetadataOutput
whose capture device is providing input to the receiver.
@param rectInOutputCoordinates
A CGRect in the receiver's coordinates.
@result
A CGRect in the coordinate space of the metadata output whose capture device is providing input to the receiver.
@discussion
AVCaptureMetadataOutput rectOfInterest is expressed as a CGRect where {0,0} represents the top left of the picture area,
and {1,1} represents the bottom right on an unrotated picture. This convenience method converts a rectangle in
the coordinate space of the receiver to a rectangle of interest in the coordinate space of an AVCaptureMetadataOutput
whose AVCaptureDevice is providing input to the receiver. The conversion takes orientation, mirroring, and scaling into
consideration. See -transformedMetadataObjectForMetadataObject:connection: for a full discussion of how orientation and mirroring
are applied to sample buffers passing through the output.
*/
- (CGRect)metadataOutputRectOfInterestForRect:(CGRect)rectInOutputCoordinates NS_AVAILABLE_IOS(7_0);
使用它来设置rectOfInterest之后就可以了。