如何使用iOS中的Objective C扫描AVCaptureVideoPreviewLayer特定区域中的条形码？

Question

我正在尝试使用目标C中的AVFoundation将条形码扫描仪实现到我的iPhone应用程序。条形码扫描部分工作正常，但问题是当前预览显示在设备的整个屏幕上，我希望扫描仪预览到显示在设备的特定区域，需要更改背景的亮度区域（请参阅下面的屏幕截图）。

如何放置AVCaptureVideoPreviewLayer的特定区域以获取带有角落的条形扫描结果？

Answer 1

我的pj中有一个例子，它在Swift中，但我猜你可以转换它，根据需要调整代码，55是每行的长度

要创建角落，也许会这样做，color是兴趣矩阵：

scanRectView

目标C代码：

func createFrame() -> CAShapeLayer {
    let height: CGFloat = self.scanRectView.frame.size.height
    let width: CGFloat = self.scanRectView.frame.size.width
    let path = UIBezierPath()
    path.move(to: CGPoint(x: 5, y: 50))
    path.addLine(to: CGPoint(x: 5, y: 5))
    path.addLine(to: CGPoint(x: 50, y: 5))
    path.move(to: CGPoint(x: height - 55, y: 5))
    path.addLine(to: CGPoint(x: height - 5, y: 5))
    path.addLine(to: CGPoint(x: height - 5, y: 55))
    path.move(to: CGPoint(x: 5, y: width - 55))
    path.addLine(to: CGPoint(x: 5, y: width - 5))
    path.addLine(to: CGPoint(x: 55, y: width - 5))
    path.move(to: CGPoint(x: width - 55, y: height - 5))
    path.addLine(to: CGPoint(x: width - 5, y: height - 5))
    path.addLine(to: CGPoint(x: width - 5, y: height - 55))
    let shape = CAShapeLayer()
    shape.path = path.cgPath
    shape.strokeColor = UIColor.white.cgColor
    shape.lineWidth = 5
    shape.fillColor = UIColor.clear.cgColor
    return shape
}

创建后，在 CGFloat height = baseScannerView.frame.size.height+4; CGFloat width = baseScannerView.frame.size.width+4; UIBezierPath* path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointMake(1, 25)]; [path addLineToPoint:CGPointMake(1, 1)]; [path addLineToPoint:CGPointMake(25, 1)]; [path moveToPoint:CGPointMake(width - 30, 1)]; [path addLineToPoint:CGPointMake(width - 5, 1)]; [path addLineToPoint:CGPointMake(width - 5, 25)]; [path moveToPoint:CGPointMake(1, height - 30)]; [path addLineToPoint:CGPointMake(1, height - 5)]; [path addLineToPoint:CGPointMake(25, height - 5)]; [path moveToPoint:CGPointMake(width - 30, height - 5)]; [path addLineToPoint:CGPointMake(width - 5, height - 5)]; [path addLineToPoint:CGPointMake(width - 5, height - 30)]; CAShapeLayer *pathLayer = [CAShapeLayer layer]; pathLayer.path = path.CGPath; pathLayer.strokeColor = [[UIColor redColor] CGColor]; pathLayer.lineWidth = 5.0f; pathLayer.fillColor = nil; [self.scanRectView.layer addSublayer:pathLayer]; 或self.scanRectView.layer.addSublayer(self.createFrame())

中添加viewWillAppear

结果：

Answer 2

你可以根据你的需要改变AVCaptureVideoPreviewLayer框架，就像这样，这是一个例子，

AVCaptureVideoPreviewLayer *_CaptureLayer;
AVCaptureSession *_Capturesession;
_Capturesession = [[AVCaptureSession alloc] init];
_CaptureLayer = [AVCaptureVideoPreviewLayer layerWithSession: 
                                             _Capturesession];
_CaptureLayer = CGRectMake(self.view.frame.origin.x, 
                    self.view.frame.origin.y+100, 
                    self.view.frame.size.width, 
                    self.view.frame.size.height/2.5);

_CaptureLayer = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer: _CaptureLayer];