移动开发平台 mPaaS 自定义 UI 下使用扫码功能

本文将引导您绘制自定义 UI 界面并将自定义 UI 扫码的能力添加到工程中。

该过程主要分为以下四个步骤：

创建依赖工程
在依赖工程中创建定义 UI 界面
在依赖工程中使用扫码功能
在主工程中调用自定义 UI 下的扫码功能

操作步骤

创建依赖工程

点击 File > New > New Module。
选择 Android Library，点击 Next。
输入 Moudle name，点击 Finish。

在依赖工程中创建定义 UI 界面

在 custom 的 com.example.custom 包中创建 widget 包。在 widget 包中添加 APSurfaceTexture 类，让其继承 SurfaceTexture 类，以获取图像流。

    
     public class APSurfaceTexture extends SurfaceTexture {
     
      private static final String TAG = "APSurfaceTexture";
     
      public SurfaceTexture mSurface;
     
      public APSurfaceTexture() {
      super(0);
      }
     
      @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
      @Override
      public void attachToGLContext(int texName) {
      mSurface.attachToGLContext(texName);
      }
     
      @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
      @Override
      public void detachFromGLContext() {
      try {
      mSurface.detachFromGLContext();
      } catch (Exception ex) {
      try {
      Method nativeMethod = SurfaceTexture.class.getDeclaredMethod("nativeDetachFromGLContext");
      nativeMethod.setAccessible(true);
      int retCode = (Integer) nativeMethod.invoke(mSurface);
      LoggerFactory.getTraceLogger().debug(TAG, "nativeDetachFromGLContext invoke retCode:" + retCode);
      } catch (Exception e) {
      LoggerFactory.getTraceLogger().error(TAG, "nativeDetachFromGLContext invoke exception:" + e.getMessage());
      }
      LoggerFactory.getTraceLogger().error(TAG, "mSurface.detachFromGLContext() exception:" + ex.getMessage());
      }
      }
     
      @Override
      public boolean equals(Object o) {
      return mSurface.equals(o);
      }
     
      @Override
      public long getTimestamp() {
      return mSurface.getTimestamp();
      }
     
      @Override
      public void getTransformMatrix(float[] mtx) {
      mSurface.getTransformMatrix(mtx);
      }
     
      @Override
      public void release() {
      super.release();
      mSurface.release();
      }
     
      @Override
      public int hashCode() {
      return mSurface.hashCode();
      }
     
      @TargetApi(Build.VERSION_CODES.KITKAT)
      @Override
      public void releaseTexImage() {
      mSurface.releaseTexImage();
      }
     
      @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1)
      @Override
      public void setDefaultBufferSize(int width, int height) {
      mSurface.setDefaultBufferSize(width, height);
      }
     
      @Override
      public void setOnFrameAvailableListener(OnFrameAvailableListener listener) {
      mSurface.setOnFrameAvailableListener(listener);
      }
     
      @Override
      public String toString() {
      return mSurface.toString();
      }
     
      @Override
      public void updateTexImage() {
      mSurface.updateTexImage();
      }
     }

在 custom 的 widget 包中添加 APTextureView 类，让其继承 TextureView 类，实现图像流的显示。

    
     public class APTextureView extends TextureView {
     
      private static final String TAG = "APTextureView";
     
      private Field mSurfaceField;
     
      public APTextureView(Context context) {
      super(context);
      }
     
      public APTextureView(Context context, AttributeSet attrs) {
      super(context, attrs);
      }
     
      public APTextureView(Context context, AttributeSet attrs, int defStyleAttr) {
      super(context, attrs, defStyleAttr);
      }
     
      @Override
      protected void onDetachedFromWindow() {
      try {
      super.onDetachedFromWindow();
      } catch (Exception ex) {
      LoggerFactory.getTraceLogger().error(TAG, "onDetachedFromWindow exception:" + ex.getMessage());
      }
      }
     
      @Override
      public void setSurfaceTexture(SurfaceTexture surfaceTexture) {
      super.setSurfaceTexture(surfaceTexture);
      afterSetSurfaceTexture();
      }
     
      private void afterSetSurfaceTexture() {
      LoggerFactory.getTraceLogger().debug(TAG, "afterSetSurfaceTexture Build.VERSION.SDK_INT:" + Build.VERSION.SDK_INT);
      if (Build.VERSION.SDK_INT < 16 || Build.VERSION.SDK_INT > 20) {
      return;
      }
     
      try {
      if (mSurfaceField == null) {
      mSurfaceField = TextureView.class.getDeclaredField("mSurface");
      mSurfaceField.setAccessible(true);
      }
     
      SurfaceTexture innerSurface = (SurfaceTexture) mSurfaceField.get(this);
      if (innerSurface != null) {
      if (!(innerSurface instanceof APSurfaceTexture)) {
      APSurfaceTexture wrapSurface = new APSurfaceTexture();
      wrapSurface.mSurface = innerSurface;
      mSurfaceField.set(this, wrapSurface);
      LoggerFactory.getTraceLogger().debug(TAG, "afterSetSurfaceTexture wrap mSurface");
      }
      }
      } catch (Exception ex) {
      LoggerFactory.getTraceLogger().error(TAG, "afterSetSurfaceTexture exception:" + ex.getMessage());
      }
      }
     }

在 com.example.custom 包中创建 Utils 类，实现图片的转换。

    
     public class Utils {
     
      private static String TAG = "Utils";
     
      public static void toast(Context context, String msg) {
      Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
      }
     
      public static Bitmap changeBitmapColor(Bitmap bitmap, int color) {
      int bitmap_w = bitmap.getWidth();
      int bitmap_h = bitmap.getHeight();
      int[] arrayColor = new int[bitmap_w * bitmap_h];
     
      int count = 0;
      for (int i = 0; i < bitmap_h; i++) {
      for (int j = 0; j < bitmap_w; j++) {
     
      int originColor = bitmap.getPixel(j, i);
      // 非透明区域
      if (originColor != 0) {
      originColor = color;
      }
     
      arrayColor[count] = originColor;
      count++;
      }
      }
      return Bitmap.createBitmap(arrayColor, bitmap_w, bitmap_h, Bitmap.Config.ARGB_8888);
      }
     
      public static Bitmap uri2Bitmap(Context context, Uri uri) {
      Bitmap bitmap = null;
      InputStream in;
      try {
      in = context.getContentResolver().openInputStream(uri);
      if (in != null) {
      bitmap = BitmapFactory.decodeStream(in);
      in.close();
      }
      } catch (Exception e) {
      LoggerFactory.getTraceLogger().error(TAG, "uri2Bitmap: Exception " + e.getMessage());
      }
      return bitmap;
      }
     }

右键点击 custom > New > Directory。
在弹出框中输入 res，创建 res 文件夹。
右键点击 custom 的 res > New > Directory。
在弹出框中输入 values，创建 values 文件夹。
右键点击 custom 的 values > New > File。
在弹出框中输入 attrs.xml，创建 attrs.xml 文件。

在 attrs.xml 文件中添加如下代码。

    
     <?xml version="1.0" encoding="utf-8"?>
     <resources>
      <declare-styleable name="scan">
      <attr name="shadowColor" format="color" />
      </declare-styleable>
     </resources>

右键点击 custom 的 res > New > Directory。
在弹出框中输入 drawable，创建 drawable 文件夹。
向 drawable 文件夹中粘贴如下资源文件。

在 custom 的 widget 包中添加 FinderView 类，让其继承 View 类，并添加如下代码。实现扫码窗口、边角及周边阴影的绘制功能。

    
     public class FinderView extends View {
     
     private static final int DEFAULT_SHADOW_COLOR = 0x96000000;
     
     private int scanWindowLeft, scanWindowTop, scanWindowRight, scanWindowBottom;
     private Bitmap leftTopCorner, rightTopCorner, leftBottomCorner, rightBottomCorner;
     private Paint paint;
     private int shadowColor;
     
     public FinderView(Context context, AttributeSet attrs, int defStyle) {
      super(context, attrs, defStyle);
      init(context, attrs);
     }
     
     public FinderView(Context context, AttributeSet attrs) {
      super(context, attrs);
      init(context, attrs);
     }
     
     private void init(Context context, AttributeSet attrs) {
      applyConfig(context, attrs);
      setVisibility(INVISIBLE);
      initCornerBitmap(context);
     
      paint = new Paint();
      paint.setAntiAlias(true);
     }
     
     private void applyConfig(Context context, AttributeSet attrs) {
      if (attrs != null) {
      TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.scan);
      shadowColor = typedArray.getColor(R.styleable.scan_shadowColor, DEFAULT_SHADOW_COLOR);
      typedArray.recycle();
      }
     }
     //初始化扫码窗口边角样式
     private void initCornerBitmap(Context context) {
      Resources res = context.getResources();
      leftTopCorner = BitmapFactory.decodeResource(res, R.drawable.scan_window_corner_left_top);
      rightTopCorner = BitmapFactory.decodeResource(res, R.drawable.scan_window_corner_right_top);
      leftBottomCorner = BitmapFactory.decodeResource(res, R.drawable.scan_window_corner_left_bottom);
      rightBottomCorner = BitmapFactory.decodeResource(res, R.drawable.scan_window_corner_right_bottom);
     }
     
     @Override
     public void draw(Canvas canvas) {
      super.draw(canvas);
      drawShadow(canvas);
      drawCorner(canvas);
     }
     //绘制扫码窗口边角样式
     private void drawCorner(Canvas canvas) {
      paint.setAlpha(255);
      canvas.drawBitmap(leftTopCorner, scanWindowLeft, scanWindowTop, paint);
      canvas.drawBitmap(rightTopCorner, scanWindowRight - rightTopCorner.getWidth(), scanWindowTop, paint);
      canvas.drawBitmap(leftBottomCorner, scanWindowLeft, scanWindowBottom - leftBottomCorner.getHeight(), paint);
      canvas.drawBitmap(rightBottomCorner, scanWindowRight - rightBottomCorner.getWidth(), scanWindowBottom - rightBottomCorner.getHeight(), paint);
     }
     //绘制扫码周边阴影
     private void drawShadow(Canvas canvas) {
      paint.setColor(shadowColor);
      canvas.drawRect(0, 0, getWidth(), scanWindowTop, paint);
      canvas.drawRect(0, scanWindowTop, scanWindowLeft, scanWindowBottom, paint);
      canvas.drawRect(scanWindowRight, scanWindowTop, getWidth(), scanWindowBottom, paint);
      canvas.drawRect(0, scanWindowBottom, getWidth(), getHeight(), paint);
     }
     
     /**
      * 根据 RayView 的位置决定扫码窗口的位置
      */
     public void setScanWindowLocation(int left, int top, int right, int bottom) {
      scanWindowLeft = left;
      scanWindowTop = top;
      scanWindowRight = right;
      scanWindowBottom = bottom;
      invalidate();
      setVisibility(VISIBLE);
     }
     
     public void setShadowColor(int shadowColor) {
      this.shadowColor = shadowColor;
     }
     //设置扫码窗口边角颜色
     public void setCornerColor(int angleColor) {
      leftTopCorner = Utils.changeBitmapColor(leftTopCorner, angleColor);
      rightTopCorner = Utils.changeBitmapColor(rightTopCorner, angleColor);
      leftBottomCorner = Utils.changeBitmapColor(leftBottomCorner, angleColor);
      rightBottomCorner = Utils.changeBitmapColor(rightBottomCorner, angleColor);
     }
     }

在 custom 的 widget 包中添加 RayView 类，让其继承 ImageView 类，并添加如下代码。实现扫描射线的绘制功能。

    
     public class RayView extends ImageView {
     
     private FinderView mFinderView;
     private ScaleAnimation scanAnimation;
     private int[] location = new int[2];
     
     public RayView(Context context, AttributeSet attrs) {
      super(context, attrs);
     }
     
     public RayView(Context context) {
      super(context);
     }
     
     @Override
     protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
      super.onLayout(changed, left, top, right, bottom);
     
      // 设置 FinderView 中扫码窗口的位置
      getLocationOnScreen(location);
      if (mFinderView != null) {
      mFinderView.setScanWindowLocation(location[0], location[1], location[0] + getWidth(), location[1] + getHeight());
      }
     }
     
     public void startScanAnimation() {
      setVisibility(VISIBLE);
      if (scanAnimation == null) {
      scanAnimation = new ScaleAnimation(1.0f, 1.0f, 0.0f, 1.0f);
      scanAnimation.setDuration(3000L);
      scanAnimation.setFillAfter(true);
      scanAnimation.setRepeatCount(Animation.INFINITE);
      scanAnimation.setInterpolator(new AccelerateDecelerateInterpolator());
      }
      startAnimation(scanAnimation);
     }
     
     public void stopScanAnimation() {
      setVisibility(INVISIBLE);
      if (scanAnimation != null) {
      this.clearAnimation();
      scanAnimation = null;
      }
     }
     
     public void setFinderView(FinderView FinderView) {
      mFinderView = FinderView;
     }
     }

右键点击 custom 的 res > New > Directory。
在弹出框中输入 layout，创建 layout 文件夹。
右键点击 custom 的 layout > New > File。
在弹出框中输入 view_scan.xml，创建 view_scan.xml 文件。

在 view_scan.xml 文件中添加如下代码，绘制扫描页面的布局界面。

    
     <?xml version="1.0" encoding="utf-8"?>
     <merge xmlns:android="http://schemas.android.com/apk/res/android">
     
      <com.example.custom.widget.FinderView
      android:id="@+id/finder_view"
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
     
      <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="20dp"
      android:gravity="center_vertical"
      android:orientation="horizontal">
     
      <ImageView
      android:id="@+id/back"
      android:layout_width="48dp"
      android:layout_height="48dp"
      android:scaleType="center"
      android:src="@drawable/icon_back" />
     
      <TextView
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_weight="1"
      android:gravity="center"
      android:text="@string/custom_title"
      android:textColor="#ffffff"
      android:textSize="16sp" />
     
      <ImageView
      android:id="@+id/gallery"
      android:layout_width="34dp"
      android:layout_height="34dp"
      android:layout_marginEnd="10dp"
      android:layout_marginRight="10dp"
      android:scaleType="fitXY"
      android:src="@drawable/selector_scan_from_gallery" />
     
      <ImageView
      android:id="@+id/torch"
      android:layout_width="34dp"
      android:layout_height="34dp"
      android:layout_marginEnd="10dp"
      android:layout_marginRight="10dp"
      android:scaleType="fitXY"
      android:src="@drawable/selector_torch" />
      </LinearLayout>
     
      <com.example.custom.widget.RayView
      android:id="@+id/ray_view"
      android:layout_width="270dp"
      android:layout_height="280dp"
      android:layout_centerInParent="true"
      android:background="@drawable/custom_scan_ray" />
     
      <TextView
      android:id="@+id/tip_tv"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/ray_view"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="10dp"
      android:includeFontPadding="false"
      android:text="@string/scan_tip"
      android:textColor="#7fffffff"
      android:textSize="14sp" />
     
     </merge>

在 widget 包中添加 ScanView 类，让其继承 RelativeLayout 类，并添加如下代码。实现扫码相关的 View 与扫码引擎的交互功能。

    
     public class ScanView extends RelativeLayout {
     
     private RayView mRayView;
     
     public ScanView(Context context) {
      super(context);
      init(context);
     }
     
     public ScanView(Context context, AttributeSet attrs) {
      super(context, attrs);
      init(context);
     }
     
     public ScanView(Context context, AttributeSet attrs, int defStyle) {
      super(context, attrs, defStyle);
      init(context);
     }
     
     private void init(Context ctx) {
      LayoutInflater.from(ctx).inflate(R.layout.view_scan, this, true);
      FinderView finderView = (FinderView) findViewById(R.id.finder_view);
      mRayView = (RayView) findViewById(R.id.ray_view);
      mRayView.setFinderView(finderView);
     }
     
     public void onStartScan() {
      mRayView.startScanAnimation();
     }
     
     public void onStopScan() {
      mRayView.stopScanAnimation();
     }
     
     public float getCropWidth() {
      return mRayView.getWidth() * 1.1f;
     }
     
     public Rect getScanRect(Camera camera, int previewWidth, int previewHeight) {
      if (camera == null) {
      return null;
      }
      int[] location = new int[2];
      mRayView.getLocationOnScreen(location);
      Rect r = new Rect(location[0], location[1],
      location[0] + mRayView.getWidth(), location[1] + mRayView.getHeight());
      Camera.Size size;
      try {
      size = camera.getParameters().getPreviewSize();
      } catch (Exception e) {
      return null;
      }
      if (size == null) {
      return null;
      }
      double rateX = (double) size.height / (double) previewWidth;
      double rateY = (double) size.width / (double) previewHeight;
      // 裁剪框大小 = 网格动画框大小＊1.1
      int expandX = (int) (mRayView.getWidth() * 0.05);
      int expandY = (int) (mRayView.getHeight() * 0.05);
      Rect resRect = new Rect(
      (int) ((r.top - expandY) * rateY),
      (int) ((r.left - expandX) * rateX),
      (int) ((r.bottom + expandY) * rateY),
      (int) ((r.right + expandX) * rateX));
     
      Rect finalRect = new Rect(
      resRect.left < 0 ? 0 : resRect.left,
      resRect.top < 0 ? 0 : resRect.top,
      resRect.width() > size.width ? size.width : resRect.width(),
      resRect.height() > size.height ? size.height : resRect.height());
     
      Rect rect1 = new Rect(
      finalRect.left / 4 * 4,
      finalRect.top / 4 * 4,
      finalRect.right / 4 * 4,
      finalRect.bottom / 4 * 4);
     
      int max = Math.max(rect1.right, rect1.bottom);
      int diff = Math.abs(rect1.right - rect1.bottom) / 8 * 4;
     
      Rect rect2;
      if (rect1.right > rect1.bottom) {
      rect2 = new Rect(rect1.left, rect1.top - diff, max, max);
      } else {
      rect2 = new Rect(rect1.left - diff, rect1.top, max, max);
      }
      return rect2;
     }
     }

右键点击 custom 的 layout > New > File。
在弹出框中输入 activity_custom_scan.xml，创建 activity_custom_scan.xml 文件。

在 activity_custom_scan.xml 文件中添加如下代码。绘制自定义扫码功能的主界面。

    
     <?xml version="1.0" encoding="utf-8"?>
     <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="match_parent">
     
      <com.mpaas.aar.demo.custom.widget.APTextureView
      android:id="@+id/surface_view"
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
     
      <com.mpaas.aar.demo.custom.widget.ScanView
      android:id="@+id/scan_view"
      android:layout_width="match_parent"
      android:layout_height="match_parent" />
     
     </FrameLayout>

在依赖工程中使用扫码功能

在 custom 的 com.example.custom 包中添加 ScanHelper 类，并添加如下代码。调用扫码功能以及获取扫码结果的回调结果。

    
     public class ScanHelper {
     
      private static class Holder {
      private static ScanHelper instance = new ScanHelper();
      }
     
      private ScanCallback scanCallback;
     
      private ScanHelper() {
      }
     
      public static ScanHelper getInstance() {
      return Holder.instance;
      }
     
      public void scan(Context context, ScanCallback scanCallback) {
      if (context == null) {
      return;
      }
      this.scanCallback = scanCallback;
      context.startActivity(new Intent(context, CustomScanActivity.class));
      }
     
      void notifyScanResult(boolean isProcessed, Intent resultData) {
      if (scanCallback != null) {
      scanCallback.onScanResult(isProcessed, resultData);
      scanCallback = null;
      }
      }
     
      public interface ScanCallback {
      void onScanResult(boolean isProcessed, Intent result);
      }
     }

在 custom 的 com.example.custom 包中添加 CustomScanActivity 类，让其继承 Activity 类。设置界面沉浸模式并创建资源文件对应的 View 和 Button。

    
     public class CustomScanActivity extends Activity {
      private final String TAG = CustomScanActivity.class.getSimpleName();
      private static final int REQUEST_CODE_PERMISSION = 1;
      private static final int REQUEST_CODE_PHOTO = 2;
      private ImageView mTorchBtn;
      private APTextureView mTextureView;
      private ScanView mScanView;
      private boolean isFirstStart = true;
      private boolean isPermissionGranted;
      private boolean isScanning;
      private boolean isPaused;
      private Rect scanRect;
      private MPScanner mpScanner;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_custom_scan);
     
      // 设置沉浸模式
      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
      getWindow().setFlags(
      WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS,
      WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
      }
     
      mTextureView = findViewById(R.id.surface_view);
      mScanView = findViewById(R.id.scan_view);
      mTorchBtn = findViewById(R.id.torch);
     
      }
     
      @Override
      public void onPause() {
      super.onPause();
     
      }
     
      @Override
      public void onResume() {
      super.onResume();
     
      }
     
      @Override
      public void onDestroy() {
      super.onDestroy();
     
      }
     
      @Override
      public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
      super.onRequestPermissionsResult(requestCode, permissions, grantResults);
     
      }
      @Override
      public void onBackPressed() {
      super.onBackPressed();
     
      }
     
      @Override
      public void onActivityResult(int requestCode, int resultCode, Intent data) {
      super.onActivityResult(requestCode, resultCode, data);
     
      }
     }

在 CustomScanActivity 中创建 pickImageFromGallery 方法，实现打开手机相册的功能。

    
      private void pickImageFromGallery() {
      Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
      intent.setType("image/*");
      startActivityForResult(intent, REQUEST_CODE_PHOTO);
      }

在 CustomScanActivity 的 onCreate 方法中添加 _ _gallery 的点击事件，并调用 pickImageFromGallery 方法。

    
      findViewById(R.id.gallery).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
      pickImageFromGallery();
      }
      });

在 switchTorch 方法中实现切换手电开关的功能。

    
      private void switchTorch() {
      boolean torchOn = mpScanner.switchTorch();
      mTorchBtn.setSelected(torchOn);
      }

在 CustomScanActivity 的 onCreate 方法中添加 mTorchBtn 的点击事件，并调用 switchTorch 方法。

    
      mTorchBtn.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
      switchTorch();
      }
      });

在 CustomScanActivity 中创建 notifyScanResult 方法。

    
      private void notifyScanResult(boolean isProcessed, Intent resultData) {
      ScanHelper.getInstance().notifyScanResult(isProcessed, resultData);
      }

在 onBackPressed 中调用 notifyScanResult 方法。

    
      @Override
      public void onBackPressed() {
      super.onBackPressed();
      notifyScanResult(false, null);
      }

在 CustomScanActivity 的 onCreate 方法中添加 _ _back 的点击事件，并调用 onBackPressed 方法。“`java

    
      findViewById(R.id.back).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
      onBackPressed();
      }
      });

“

在 CustomScanActivity 中创建 initMPScanner 方法，并使用 mpScanner 对象的 setRecognizeType 方法设置识别码的类型。

    
     private void initMPScanner() { 
      mpScanner = new MPScanner(this);
      mpScanner.setRecognizeType(
      MPRecognizeType.QR_CODE,
      MPRecognizeType.BAR_CODE,
      MPRecognizeType.DM_CODE,
      MPRecognizeType.PDF417_CODE
      );
     }

在 CustomScanActivity 中创建 onScanSuccess 方法，并实现如下代码。

    
     private void onScanSuccess(final MPScanResult result) {
      runOnUiThread(new Runnable() {
      @Override
      public void run() {
      if (result == null) {
      notifyScanResult(true, null);
      } else {
      Intent intent = new Intent();
      intent.setData(Uri.parse(result.getText()));
      notifyScanResult(true, intent);
      }
      CustomScanActivity.this.finish();
      }
      });
     }

在 CustomScanActivity 中创建 initScanRect 方法，初始化扫描功能。调用 mpScanner 对象的 getCamera 方法获取 Camera 对象并调用 mpScanner 对象的 setScanRegion 方法设置扫描区域。

    
     private void initScanRect() {
      if (scanRect == null) {
      scanRect = mScanView.getScanRect(
      mpScanner.getCamera(), mTextureView.getWidth(), mTextureView.getHeight());
     
      float cropWidth = mScanView.getCropWidth();
      LoggerFactory.getTraceLogger().debug(TAG, "cropWidth: " + cropWidth);
      if (cropWidth > 0) {
      // 预览放大 ＝ 屏幕宽 ／ 裁剪框宽
      WindowManager wm = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
      float screenWith = wm.getDefaultDisplay().getWidth();
      float screenHeight = wm.getDefaultDisplay().getHeight();
      float previewScale = screenWith / cropWidth;
      if (previewScale < 1.0f) {
      previewScale = 1.0f;
      }
      if (previewScale > 1.5f) {
      previewScale = 1.5f;
      }
      LoggerFactory.getTraceLogger().debug(TAG, "previewScale: " + previewScale);
      Matrix transform = new Matrix();
      transform.setScale(previewScale, previewScale, screenWith / 2, screenHeight / 2);
      mTextureView.setTransform(transform);
      }
      }
      mpScanner.setScanRegion(scanRect);
     }

在 initMPScanner 方法中使用 mpScanner 对象的 setMPScanListener 方法实现扫描监听器的功能。

    
     mpScanner.setMPScanListener(new MPScanListener() {
      @Override
      public void onConfiguration() {
      mpScanner.setDisplayView(mTextureView);
      }
     
      @Override
      public void onStart() {
      if (!isPaused) {
      runOnUiThread(new Runnable() {
      @Override
      public void run() {
      if (!isFinishing()) {
      initScanRect();
      mScanView.onStartScan();
      }
      }
      });
      }
      }
     
      @Override
      public void onSuccess(MPScanResult mpScanResult) {
      mpScanner.beep();
      onScanSuccess(mpScanResult);
      }
     
      @Override
      public void onError(MPScanError mpScanError) {
      if (!isPaused) {
      runOnUiThread(new Runnable() {
      @Override
      public void run() {
      Utils.toast(CustomScanActivity.this, getString(R.string.camera_open_error));
      }
      });
      }
      }
      });

在 initMPScanner 方法中使用 mpScanner 对象的 setMPImageGrayListener 方法实现识别图像灰度值的监听功能。

    
      mpScanner.setMPImageGrayListener(new MPImageGrayListener() {
      @Override
      public void onGetImageGray(int gray) {
      // 注意：该回调在昏暗环境下可能会连续多次执行
      if (gray < MPImageGrayListener.LOW_IMAGE_GRAY) {
      runOnUiThread(new Runnable() {
      @Override
      public void run() {
      Utils.toast(CustomScanActivity.this, "光线太暗，请打开手电筒");
      }
      });
      }
      }
      });
     }

在 CustomScanActivity 中分别创建 startScan 和 stopScan 方法，实现开启和关闭相机扫码权限。

    
     private void startScan() {
      try {
      mpScanner.openCameraAndStartScan();
      isScanning = true;
      } catch (Exception e) {
      isScanning = false;
      LoggerFactory.getTraceLogger().error(TAG, "startScan: Exception " + e.getMessage());
      }
     }
     
     private void stopScan() {
      mpScanner.closeCameraAndStopScan();
      mScanView.onStopScan();
      isScanning = false;
      if (isFirstStart) {
      isFirstStart = false;
      }
     }

在 CustomScanActivity 中创建 onPermissionGranted 方法。

    
     private void onPermissionGranted() {
      isPermissionGranted = true;
      startScan();
     }

在 CustomScanActivity 中创建 checkCameraPermission 方法。

    
     private void checkCameraPermission() {
      if (PermissionChecker.checkSelfPermission(
      this, Manifest.permission.CAMERA) != PermissionChecker.PERMISSION_GRANTED) {
      ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CODE_PERMISSION);
      } else {
      onPermissionGranted();
      }
     }

在 CustomScanActivity 中创建 scanFromUri 方法。

    
     private void scanFromUri(Uri uri) {
      final Bitmap bitmap = Utils.uri2Bitmap(this, uri);
      if (bitmap == null) {
      notifyScanResult(true, null);
      finish();
      } else {
      new Thread(new Runnable() {
      @Override
      public void run() {
      MPScanResult mpScanResult = mpScanner.scanFromBitmap(bitmap);
      mpScanner.beep();
      onScanSuccess(mpScanResult);
      }
      }, "scanFromUri").start();
      }
     }

在 CustomScanActivity 的 onCreate 方法中调用 checkCameraPermission 方法检查相机权限。
```
    
     checkCameraPermission();
    
```

在 CustomScanActivity 的 onPause、onResume、onDestroy、onRequestPermissionsResult 和 onActivityResult 方法中分别添加如下内容。

    
     @Override
     public void onPause() {
      super.onPause();
      isPaused = true;
      if (isScanning) {
      stopScan();
      }
     }
     
     @Override
     public void onResume() {
      super.onResume();
      isPaused = false;
      if (!isFirstStart && isPermissionGranted) {
      startScan();
      }
     }
     
     @Override
     public void onDestroy() {
      super.onDestroy();
      mpScanner.release();
     } 
     @Override
     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
      super.onRequestPermissionsResult(requestCode, permissions, grantResults);
      if (requestCode == REQUEST_CODE_PERMISSION) {
      int length = Math.min(permissions.length, grantResults.length);
      for (int i = 0; i < length; i++) {
      if (TextUtils.equals(permissions[i], Manifest.permission.CAMERA)) {
      if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
      Utils.toast(this, getString(R.string.camera_no_permission));
      } else {
      onPermissionGranted();
      }
      break;
      }
      }
      }
      @Override
      public void onActivityResult(int requestCode, int resultCode, Intent data) {
      super.onActivityResult(requestCode, resultCode, data);
      if (data == null) {
      return;
      }
      if (requestCode == REQUEST_CODE_PHOTO) {
      scanFromUri(data.getData());
      }
     }
     }

在 custom 的 AndroidManifest.xml 文件中设置 CustomScanActivity 为 custom 的主入口。

    
     <?xml version="1.0" encoding="utf-8"?>
     <manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.mpaas.aar.demo.custom">
     
      <application>
      <meta-data
      android:name="com.google.android.actions"
      android:resource="@xml/actions" />
     
      <activity
      android:name=".CustomScanActivity"
      android:configChanges="orientation|keyboardHidden|navigation"
      android:exported="false"
      android:launchMode="singleTask"
      android:screenOrientation="portrait"
      android:theme="@android:style/Theme.NoTitleBar"
      android:windowSoftInputMode="adjustResize|stateHidden" />
      </application>
     
     </manifest>

在主工程中调用自定义 UI 下的扫码功能

在 activity_main.xml 文件中，添加 Button，并设置 Button 的 id 为 custom_ui_btn。

    
      <Button
      android:id="@+id/custom_ui_btn"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="208dp"
      android:background="#108EE9"
      android:gravity="center"
      android:text="自定义 UI 下使用扫一扫"
      android:textColor="#ffffff"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintHorizontal_bias="0.0"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent" />

在 MainActivity 类中编写代码。添加 custom_ui_btn 按钮的点击事件。获取自定义 UI 界面，并使用自定义 UI 的扫码功能。代码如下所示：

    
     findViewById(R.id.custom_ui_btn).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
      ScanHelper.getInstance().scan(MainActivity.this, new ScanHelper.ScanCallback() {
      @Override
      public void onScanResult(boolean isProcessed, Intent result) {
      if (!isProcessed) {
      // 扫码界面点击物理返回键或左上角返回键
      return;
      }
     
      if (result == null || result.getData() == null) {
      Toast.makeText(MainActivity.this, "扫码失败，请重试！", Toast.LENGTH_SHORT).show();
      return;
      }
      new AlertDialog.Builder(MainActivity.this)
      .setMessage(result.getData().toString())
      .setPositiveButton(R.string.confirm, null)
      .create()
      .show();
      }
      });
      }
      });