使用 Google Play Services – Vision 掃描 QRCode

李昀峻 2019/12/27 19:31:46

0 1553

前言:

當我們使用Xamarin.Andriod 要掃描QRCode時, 可以使用Google Play Services – Vision。

需做以下步驟

Android Support Library v7 AppCompat
Xamarin Android Support v4
Google Play Services – Vision

安裝NuGet套件

步驟一: Android Support Library v7 AppCompat

步驟二: Xamarin Android Support v4

步驟三: Google Play Services – Vision

這次要做的是第一頁有一個掃描圖示, 案下去圖示到第二頁開啟照相機, 掃描完成後帶值回第一頁。

第一頁:

axml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:app="http://schemas.android.com/apk/res-auto"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent">

<LinearLayout

android:id="@+id/linScanBarCode"

android:layout_width="250.0dp"

android:layout_height="180dp"

android:layout_gravity="center"

android:layout_marginBottom="10dp"

android:layout_marginTop="20dp"

android:gravity="center"

android:orientation="vertical">

<ImageView

android:id="@+id/imageView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:src="@mipmap/pictures_ic_barcode" />

<TextView

android:id="@+id/txtQRCode"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

android:text=""

android:textSize="14sp" />

</LinearLayout>

</RelativeLayout>

C# Code

using Android.App;

using Android.OS;

using Android.Support.V7.App;

using Android.Runtime;

using Android.Widget;

using Android.Content;

namespace QRCodeReader

{

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]

public class MainActivity : AppCompatActivity

{

/// <summary>

/// 掃描QRCode觸控區塊

/// </summary>

/// <value>The lin scan bar code.</value>

private LinearLayout linScanBarCode;

private const int SCANNING_REQUEST_CODE = 1;

protected override void OnCreate(Bundle savedInstanceState)

{

base.OnCreate(savedInstanceState);

// Set our view from the "main" layout resource

SetContentView(Resource.Layout.activity_main);

linScanBarCode = FindViewById<LinearLayout>(Resource.Id.linScanBarCode);

linScanBarCode.Click += (sender, e) =>

{

var intentCameraATY = new Intent(this, typeof(CameraATY));

StartActivityForResult(intentCameraATY, SCANNING_REQUEST_CODE);

};

}

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)

{

base.OnActivityResult(requestCode, resultCode, data);

var txtQRCode = FindViewById<TextView>(Resource.Id.txtQRCode);

if (requestCode == SCANNING_REQUEST_CODE)

{

if (data != null)

{

var QRCode = data.GetStringExtra("QRCode");

txtQRCode.Text = QRCode;

}

第二頁

Camera.axml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="@android:color/black">

<SurfaceView

android:id="@+id/cameraView"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layout_centerInParent="true" />

</RelativeLayout>

CameraATY.cs

using Android.App;

using Android.Content;

using Android.OS;

using Android.Content.PM;

using Android.Views;

using Android.Graphics;

using Android.Gms.Vision.Barcodes;

using static Android.Gms.Vision.Detector;

using Android.Util;

using Android.Gms.Vision;

using Android.Runtime;

using Android.Support.V4.App;

using Android;

using QRCodeReader;

using System.IO;

using Android.Support.V4.Content;

namespace QRCodeReader

{

[Activity(Label = "CameraATY", ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.KeyboardHidden, WindowSoftInputMode = SoftInput.AdjustPan, ScreenOrientation = Android.Content.PM.ScreenOrientation.UserLandscape)]

/// <summary>

/// 掃描同意書編號

/// </summary>

public class CameraATY : Activity, ISurfaceHolderCallback, IProcessor

{

SurfaceView surfaceView;

//TextView txtResult;

BarcodeDetector barcodeDetector;

CameraSource cameraSource;

protected override void OnCreate(Bundle savedInstanceState)

{

base.OnCreate(savedInstanceState);

SetContentView(Resource.Layout.Camera);

var permissions = new string[] { Manifest.Permission.Camera };

if (!ActivityCompat.ShouldShowRequestPermissionRationale(this, Manifest.Permission.Camera))

{

ActivityCompat.RequestPermissions(this, permissions, 100);

}

this.surfaceView = (SurfaceView)FindViewById(Resource.Id.cameraView);

// 選擇掃描格式

BarcodeDetector barcodeDetector = new BarcodeDetector.Builder(this).SetBarcodeFormats(BarcodeFormat.QrCode).Build();

cameraSource = new CameraSource.Builder(this, barcodeDetector).SetFacing(CameraFacing.Back).SetAutoFocusEnabled(true).Build();

surfaceView.Holder.AddCallback(this);

barcodeDetector.SetProcessor(this);

}

public void ReceiveDetections(Detections detections)

{

SparseArray qrcodes = detections.DetectedItems;

if (qrcodes.Size() != 0)

{

var QRCode = ((Barcode)qrcodes.ValueAt(0)).RawValue;

var intent = new Intent(this, typeof(MainActivity));

intent.PutExtra("QRCode", QRCode);

SetResult(Result.Ok, intent);

Finish();

}

public void Release()

{

}

public void SurfaceChanged(ISurfaceHolder holder, [GeneratedEnum] Format format, int width, int height)

{

}

public void SurfaceCreated(ISurfaceHolder holder)

{

cameraSource.Start(surfaceView.Holder);

}

public void SurfaceDestroyed(ISurfaceHolder holder)

{

cameraSource.Stop();

}

這段可以選擇你要的格式QrCode, 或是Code39條碼

開啟相機

ReceiveDetections會一直執行, 當感應到值得時候Size會大於0, 就可將直傳回第一

頁

Activity傳直是使用startActivityForResult( ) 的方法

startActivityForResult與startActivity的不同之處在於:
1、startActivity( )
僅僅是跳轉到目標頁面,若是想跳回當前頁面,則必須再使用一次startActivity( )。
2、startActivityForResult( )
可以一次性完成這項任務,當程式執行到這段程式碼的時候,假若從T1Activity跳轉到下一個Text2Activity,而當這個Text2Activity呼叫了finish()方法以後,程式會自動跳轉回T1Activity,並呼叫前一個T1Activity中的onActivityResult( )方法。