Question

我尝试使用angular实现NativeScript中的条形码扫描程序。我能够显示视频图层，但不幸的是我被困在处理条形码扫描事件。

我认为主要的问题是setMetadataObjectsDelegateQueue没有按预期工作。这意味着在函数captureOutputDidOutputMetadataObjectsFromConnection永远不会被调用。

在我的template.html中，我得到了一个占位符，它将被creationView模板替换。

我是在正确的轨道还是我错过了什么。不幸的是，我无法使用nativescript-barcodescanner插件，因为我想在现有布局中显示扫描仪。

import { Component, OnInit } from "@angular/core";
import {ios} from "application";

   class BarcodeDelegate implements AVCaptureMetadataOutputObjectsDelegate {

    captureOutputDidOutputMetadataObjectsFromConnection(captureOutput: AVCaptureOutput, metadataObjects: NSArray<any>, connection: AVCaptureConnection) {
        console.log('test');
    }
}

@Component({
    selector: "ns-s",
    moduleId: module.id,
    templateUrl: "./test.component.html",
})
export class TestComponent implements OnInit {

    public init: boolean = false;

    public device: AVCaptureDevice;

    ngOnInit() {
        this.init = true;
    }

    creatingView(args) {

        let session = new AVCaptureSession();
        session.sessionPreset = AVCaptureSessionPreset1280x720;

        // Adding capture device
        this.device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo);
        let input = AVCaptureDeviceInput.deviceInputWithDeviceError(this.device, null);

        if (!input) {
            throw new Error("Error trying to open camera.");
        }

        session.addInput(input);

        // Layer for outputing AV Stuff
        let videoLayer = AVCaptureVideoPreviewLayer.layerWithSession(session);
        videoLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

        let metadataOutput = new AVCaptureMetadataOutput();

        if (session.canAddOutput(metadataOutput)) {

            session.addOutput(metadataOutput);

            try {

                let delegate = new BarcodeDelegate();

                // mainQueue var is to get dispatch_get_main_queue
                let mainQueue = (function() {
                    let runloop = CFRunLoopGetMain();
                    return function(func) {
                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, func);
                        CFRunLoopWakeUp(runloop);
                    }
                }());
                    metadataOutput.setMetadataObjectsDelegateQueue(delegate, mainQueue);
                    metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN8Code,
                           AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypePDF417Code
                    ];

            } catch(e) {
                console.log(e);
            }

        } else {
            console.log('error')
        }
        session.startRunning();

        let view = UIView.alloc().initWithFrame({ origin: { x: 0, y: 0 }, size: { width: 400, height: 200 } });
        videoLayer.frame = view.bounds;
        view.layer.addSublayer(videoLayer);
        args.view = view;
    }
}

使用AVFoundation（ios）扫描NativeScript中的条形码

0 个答案: