如何在自定义UI下使用扫码功能_移动开发平台 mPaaS(mPaaS)-阿里云帮助中心

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。

如需在自定义 UI 下使用扫码功能，请参考代码示例。

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

单击 File > New > New Module。
选择 Android Library，单击 Next。
输入 Module name，单击 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;
 }
}

在 custom 中创建 res > values > attrs.xml 文件并添加如下代码。

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

在 custom 的 res > 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;
}
}

在 custom 的 res 中创建 layout > File > view_scan.xml 文件，并添加如下代码，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;
}
}

在 custom 的 layout 文件夹中创建 activity_custom_scan.xml 文件并添加如下代码。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);

 }
}

实现打开手机相册的功能。

在 CustomScanActivity 中创建 pickImageFromGallery 方法。

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

onCreate 方法中添加 gallery 的单击事件，并调用 pickImageFromGallery 方法。

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

实现切换手电开关的功能。

在 CustomScanActivity 中创建 switchTorch 方法。

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

onCreate 方法中添加 mTorchBtn 的单击事件，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，onBackPressed 中调用 notifyScanResult 方法。

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

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

在 CustomScanActivity 的 onCreate 方法中添加 back 的单击事件，并调用 onBackPressed 方法。

     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);
}

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));
                }
            });
        }
    }
});

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、checkCameraPermission 方法和 scanFromUri 方法。

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

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();
    }
}

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>
        <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 按钮的单击事件。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) {
                         // 扫码界面单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();
                 }
             });
         }
     });

编译运行工程后，单击 自定义 UI 下使用扫一扫 后即可使用自定义 UI 下的扫码功能。
扫描二维码，会弹出该二维码的信息。