自定义二维码扫描

前言

项目中需要对二维码进行扫描，第一个想到的自然就是Zxing。于是去查看了Google的官方Demo：Github：Zxing Demo

发现Demo中包含的元素实在是过多，于是决定自己搭建一个简易的二维码扫描工具，方便实现自己的需求，可能其中很多优化都没有去做，但是胜在简和易。

多简易？直接拉到最底部，看下使用文档吧。

正文

二维码扫描的逻辑应当是：

1. 打开摄像头并获取摄像头加载的图像流数据
2. 不断的截取图像中扫描框内的数据（扫描框其实是为了提高二维码的精度和识别率）
3. 将二维码数据进行灰度处理
4. 解析数据

绘制扫描框

1. 创建自定义View

   /**
    * 二维码解析的view
    * Created by yooking on 2020/6/28.
    * Copyright (c) 2020 yooking. All rights reserved.
    */
   public class ZXingView extends View{}

2. 重写

   public ZXingView(Context context) {
       super(context);
   }
   
   public ZXingView(Context context, @Nullable AttributeSet attrs) {
       super(context, attrs);
       initView(context, attrs);
   }
   
   public ZXingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
       super(context, attrs, defStyleAttr);
       initView(context, attrs);
   }

3. 其中initView(Context context, @Nullable AttributeSet attrs)方法用于加载自定义布局

   private void initView(Context context, @Nullable AttributeSet attrs) {
       TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ZXingView);
       //扫描框 宽度
       decodeWidth = typedArray.getDimension(R.styleable.ZXingView_decode_width, decodeWidth);
       //扫描框 高度
       decodeHeight = typedArray.getDimension(R.styleable.ZXingView_decode_height, decodeHeight);
       //扫描框 左上角 Y轴点坐标
       decodeTop = typedArray.getDimension(R.styleable.ZXingView_decode_top, decodeTop);
       //扫描框 左上角 X轴点坐标
       decodeLeft = typedArray.getDimension(R.styleable.ZXingView_decode_left, decodeLeft);
   
       //扫描框 线条 长度
       frameLength = typedArray.getDimension(R.styleable.ZXingView_frame_length, frameLength);
       //扫描框 线条 宽度
       frameWidth = typedArray.getDimension(R.styleable.ZXingView_frame_width, frameWidth);
       //扫描框 线条 颜色
       frameColor = typedArray.getColor(R.styleable.ZXingView_frame_color, frameColor);
   
       //扫描线条 宽度
       scanLineWidth = typedArray.getDimension(R.styleable.ZXingView_line_width,scanLineWidth);
       //扫描线条 模糊度（越大越模糊）
       scanLineRadius = typedArray.getDimension(R.styleable.ZXingView_line_radius,scanLineRadius);
       
       typedArray.recycle();
   }

4. 界面初始化完毕后，定义各项数值（重写onMeasure）

   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
       super.onMeasure(widthMeasureSpec, heightMeasureSpec);
       if (getMeasuredWidth() != 0) {
           measuredWidth = getMeasuredWidth();
           measuredHeight = getMeasuredHeight();
   
           //当扫描框宽度大于整体布局宽度 或者扫描框宽度为0时，扫描框宽度为整体布局的3/4
           if (decodeWidth == 0f || decodeWidth > measuredWidth) {
               decodeWidth = measuredWidth * 3 / 4f;
           }
           //当扫描框高度为0时，扫描框高度与宽度相等
           if (decodeHeight == 0f) {
               decodeHeight = decodeWidth * 1f;
           }
           //当扫描框高度超过整体布局高度时，扫描框高度为整体布局的3/4
           if (decodeHeight > measuredHeight) {
               decodeHeight = measuredHeight * 3 / 4f;
           }
   
           //当扫描框与左边间距为-1时，扫描框居中
           if (decodeLeft == -1f) {
               decodeLeft = (measuredWidth - decodeWidth) / 2f;
           }
   
           //当扫描框超出整体布局宽度时，扫描框居中
           if (decodeLeft + decodeWidth > measuredWidth) {
               decodeWidth = measuredWidth * 3 / 4f;
               decodeLeft = (measuredWidth - decodeWidth) / 2f;
           }
   
           //当扫描框与上方间距为-1时，扫描框距离上方为1/6整体高度
           if (decodeTop == -1f) {
               decodeTop = measuredHeight / 6f;
           }
   
           //当扫描框超出整体布局高度时，扫描框距离上方为1/6整体高度
           if (decodeTop + decodeHeight > measuredHeight) {
               decodeHeight = measuredHeight * 3 / 4f;
               decodeTop = (measuredHeight - decodeHeight) / 2f;
           }
       }
   }

5. 开始绘制扫描框：

   初始化画笔：

   private void initPaint() {
       if (paint == null) {
           paint = new Paint();
           paint.setColor(frameColor);
   //        paint.setStrokeWidth(frameWidth);
       }
   
       if (maskPaint == null) {
           maskPaint = new Paint();
           maskPaint.setColor(getResources().getColor(R.color.color_aa000000));
       }
   
       if (scanPaint == null) {
           scanPaint = new Paint();
           scanPaint.setColor(frameColor);
           scanPaint.setShadowLayer(scanLineRadius, 0F, 0F, frameColor);
       }
   }

   界面绘制

   @Override
   protected void onDraw(Canvas canvas) {
       super.onDraw(canvas);
       initPaint();
   
       //绘制上方蒙版部分
       canvas.drawRect(0, 0, measuredWidth, decodeTop, maskPaint);
       //绘制左侧蒙版部分
       canvas.drawRect(0, decodeTop, decodeLeft, decodeTop + decodeHeight, maskPaint);
       //绘制右侧蒙版部分
       canvas.drawRect(decodeLeft + decodeWidth, decodeTop, measuredWidth, decodeTop + decodeHeight, maskPaint);
       //绘制下方蒙版部分
       canvas.drawRect(0, decodeTop + decodeHeight, measuredWidth, measuredHeight, maskPaint);
   
       //绘制方框
   
       //左上
       canvas.drawRect(decodeLeft, decodeTop, decodeLeft + frameLength, decodeTop + frameWidth, paint);
       canvas.drawRect(decodeLeft, decodeTop, decodeLeft + frameWidth, decodeTop + frameLength, paint);
   
       //右上
       canvas.drawRect(decodeLeft + decodeWidth - frameLength, decodeTop, decodeLeft + decodeWidth, decodeTop + frameWidth, paint);
       canvas.drawRect(decodeLeft + decodeWidth - frameWidth, decodeTop, decodeLeft + decodeWidth, decodeTop + frameLength, paint);
   
       //左下
       canvas.drawRect(decodeLeft, decodeTop + decodeHeight - frameLength, decodeLeft + frameWidth, decodeTop + decodeHeight, paint);
       canvas.drawRect(decodeLeft, decodeTop + decodeHeight - frameWidth, decodeLeft + frameLength, decodeTop + decodeHeight, paint);
   
       //右下
       canvas.drawRect(decodeLeft + decodeWidth - frameWidth, decodeTop + decodeHeight - frameLength, decodeLeft + decodeWidth, decodeTop + decodeHeight, paint);
       canvas.drawRect(decodeLeft + decodeWidth - frameLength, decodeTop + decodeHeight - frameWidth, decodeLeft + decodeWidth, decodeTop + decodeHeight, paint);
   
       //在方框内绘制扫描线条
       float moveY = decodeHeight * updateDuration / scanDuration;
       if (scanLineY == 0) {
           scanLineY = decodeTop;
       }
       scanLineY += moveY;
       if (scanLineY > decodeTop + decodeHeight) {
           scanLineY = decodeTop;
       }
       canvas.drawRect(decodeLeft, scanLineY, decodeLeft + decodeWidth, scanLineY + scanLineWidth, scanPaint);
   
       postInvalidateDelayed(updateDuration, (int) decodeLeft, (int) decodeTop, (int) (decodeLeft + decodeWidth), (int) (decodeTop + decodeHeight));
   }

打造Activity

1. 创建AbstractZXingActivity抽象类

   /**
    * ZXing类 Activity类
    * Created by yooking on 2020/6/29.
    * Copyright (c) 2020 yooking. All rights reserved.
    */
   public abstract class AbstractZXingActivity extends Activity {
       @Override
       protected void onCreate(@Nullable Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(getLayoutId());
           surfaceView = findViewById(getSurfaceId());
           holder = surfaceView.getHolder();
   
           holder.addCallback(holderCallback() == null ? defHolderCallback() : holderCallback());
   
           initCreate(savedInstanceState);
       }
       
       /**
        * 抽象方法 获取布局Id
        */
       public abstract @LayoutRes
       int getLayoutId();
   
       /**
        * 抽象方法 获取SurfaceViewId
        */
       public abstract @IdRes
       int getSurfaceId();
       
       public abstract void initCreate(@Nullable Bundle savedInstanceState);
   
       /**
        * 如果需要，可以自定义SurfaceHolder.Callback
        */
       public abstract SurfaceHolder.Callback holderCallback();
       
       /**
        * 如无需要，{@link this#holderCallback} return null即可
        */
       public SurfaceHolder.Callback defHolderCallback() {
           return new SurfaceHolder.Callback() {
               @Override
               public void surfaceCreated(SurfaceHolder holder) {
                   CameraManager.getInstance().openCamera();
               }
   
               @Override
               public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                   try {
                       CameraManager.getInstance().bindHolder(holder);
                       CameraManager.getInstance().startPreview();
                       
                       //解析图像属于轻耗时操作，可能会导致界面卡顿，所以使用异步线程执行
                       CameraManager.getInstance().cameraPreviewCallback(new Camera.PreviewCallback() {
                           @Override
                           public void onPreviewFrame(final byte[] data, final Camera camera) {
                               if (!isNeedDecode) return;//如果不需要扫描直接return - （防止重复扫描同个二维码）
   
                               long now = new Date().getTime();
                               if (now - lastTime > shotDuration) {//设定经过duration时间后才会进行第二次二维码扫描（如果上次没成功的话）
                                   lastTime = now;
                                   AsyncTask.execute(new Runnable() {
                                       @Override
                                       public void run() {
                                           //图像的灰度处理
                                           Bitmap bitmap = BitmapUtils.toGrayScale(screenshot(data, camera));
                                           String decodeStr;
                                           try {
                                               //解析二维码
                                               decodeStr = ZXingUtils.decode2String(bitmap);
                                           } catch (Exception e) {
                                               e.printStackTrace();
                                               decodeStr = null;
                                           }
                                           //二维码解析成功，回收bitmap
                                           if (bitmap != null)
                                               bitmap.recycle();
                                           if (callback != null && decodeStr != null && !decodeStr.isEmpty()) {
                                               callback.success(decodeStr);
                                               isNeedDecode = false;
                                           } else {
                                               //扫描不到数据，相机重新对焦
                                               CameraManager.getInstance().startFocus();
                                           }
                                       }
                                   });
                               }
                           }
                       });
                   } catch (
                           IOException e) {
                       e.printStackTrace();
                   }
               }
   
               @Override
               public void surfaceDestroyed(SurfaceHolder holder) {
                   CameraManager.getInstance().release();
               }
           };
       }
   }

结语

余下代码请在Demo中查阅，如有疑问，欢迎留言，使用方法请查看github：ReadMe

Github：Zxing Demo By yooking