Android 二维码扫描框 加四个角及中间横线自动下滑

红色为加四个角  黄色为扫描线自动下滑

/*
 * Copyright (C) 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.zxing.view;

import java.util.Collection;
import java.util.HashSet;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;

import com.bawei.zxingdemo.R;
import com.google.zxing.ResultPoint;
import com.zxing.camera.CameraManager;

/**
 * This view is overlaid on top of the camera preview. It adds the viewfinder
 * rectangle and partial transparency outside it, as well as the laser scanner
 * animation and result points. 锟皆讹拷锟斤拷锟絍iew锟斤拷锟斤拷锟斤拷时锟叫硷拷锟斤拷示锟斤拷
 */
public final class ViewfinderView extends View {

    private static final int[] SCANNER_ALPHA = { 0, 64, 128, 192, 255, 192,
            128, 64 };
    private static final long ANIMATION_DELAY = 100L;
    private static final int OPAQUE = 0xFF;

    private final Paint paint;
    private Bitmap resultBitmap;
    private final int maskColor;
    private final int resultColor;
    private final int frameColor;
    private final int laserColor;
    private final int resultPointColor;
    private int scannerAlpha;
    /**
     * 四个绿色边角对应的长度
     */
    private int ScreenRate;  

    /**
     * 四个绿色边角对应的宽度
     */
    private static final int CORNER_WIDTH = 10;
    /**
     * 手机的屏幕密度
     */
    private static float density;
    private Collection<ResultPoint> possibleResultPoints;
    private Collection<ResultPoint> lastPossibleResultPoints;
    int  count=0;
    // This constructor is used when the class is built from an XML resource.
    public ViewfinderView(Context context, AttributeSet attrs) {
        super(context, attrs);

        // Initialize these once for performance rather than calling them every
        // time in onDraw().
        paint = new Paint();
        Resources resources = getResources();
        maskColor = resources.getColor(R.color.viewfinder_mask);
        resultColor = resources.getColor(R.color.result_view);
        frameColor = resources.getColor(R.color.viewfinder_frame);
        laserColor = resources.getColor(R.color.viewfinder_laser);
        resultPointColor = resources.getColor(R.color.possible_result_points);
        scannerAlpha = 0;
        possibleResultPoints = new HashSet<ResultPoint>(5);
          density = context.getResources().getDisplayMetrics().density;
            //将像素转换成dp
            ScreenRate = (int)(20 * density);
    }

    @Override
    public void onDraw(Canvas canvas) {
        // 涓棿鐨勬壂鎻忔锛屼綘瑕佷慨鏀规壂鎻忔鐨勫ぇ灏忥紝鍘籆ameraManager閲岄潰淇敼
        Rect frame = CameraManager.get().getFramingRect();
        if (frame == null) {
            return;
        }
        // 鑾峰彇灞忓箷鐨勫鍜岄珮
        int width = canvas.getWidth();
        int height = canvas.getHeight();

        // Draw the exterior (i.e. outside the framing rect) darkened
        //鐢诲嚭鎵弿妗嗗闈㈢殑闃村奖閮ㄥ垎锛屽叡鍥涗釜閮ㄥ垎锛屾壂鎻忔鐨勪笂闈㈠埌灞忓箷涓婇潰锛屾壂鎻忔鐨勪笅闈㈠埌灞忓箷涓嬮潰
        //鎵弿妗嗙殑宸﹁竟闈㈠埌灞忓箷宸﹁竟锛屾壂鎻忔鐨勫彸杈瑰埌灞忓箷鍙宠竟
        paint.setColor(resultBitmap != null ? resultColor : maskColor);
        canvas.drawRect(0, 0, width, frame.top, paint);
        canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, paint);
        canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1,
                paint);
        canvas.drawRect(0, frame.bottom + 1, width, height, paint);

        if (resultBitmap != null) {
            // Draw the opaque result bitmap over the scanning rectangle
            paint.setAlpha(OPAQUE);
            canvas.drawBitmap(resultBitmap, frame.left, frame.top, paint);
        } else {

            //鐢绘壂鎻忔杈逛笂鐨勮锛屾�诲叡8涓儴鍒�
            // Draw a two pixel solid black border inside the framing rect
            paint.setColor(frameColor);
            canvas.drawRect(frame.left, frame.top, frame.right + 1,
                    frame.top + 2, paint);
            canvas.drawRect(frame.left, frame.top + 2, frame.left + 2,
                    frame.bottom - 1, paint);
            canvas.drawRect(frame.right - 1, frame.top, frame.right + 1,
                    frame.bottom - 1, paint);
            canvas.drawRect(frame.left, frame.bottom - 1, frame.right + 1,
                    frame.bottom + 1, paint);

            // Draw a red "laser scanner" line through the middle to show
            // decoding is active
             //鐢绘壂鎻忔涓嬮潰鐨勫瓧
            paint.setColor(laserColor);
            paint.setAlpha(SCANNER_ALPHA[scannerAlpha]);
            scannerAlpha = (scannerAlpha + 1) % SCANNER_ALPHA.length;
            int middle = count%frame.height()  + frame.top;
            canvas.drawRect(frame.left + 2, middle - 1, frame.right - 1,
                    middle + 2, paint);
              count+=3;

            //画扫描框边上的角，总共8个部分
             paint.setColor(Color.GREEN);
              canvas.drawRect(frame.left, frame.top, frame.left + ScreenRate,
                      frame.top + CORNER_WIDTH, paint);
              canvas.drawRect(frame.left, frame.top, frame.left + CORNER_WIDTH, frame.top
                      + ScreenRate, paint);
              canvas.drawRect(frame.right - ScreenRate, frame.top, frame.right,
                      frame.top + CORNER_WIDTH, paint);
              canvas.drawRect(frame.right - CORNER_WIDTH, frame.top, frame.right, frame.top
                      + ScreenRate, paint);
              canvas.drawRect(frame.left, frame.bottom - CORNER_WIDTH, frame.left
                      + ScreenRate, frame.bottom, paint);
              canvas.drawRect(frame.left, frame.bottom - ScreenRate,
                      frame.left + CORNER_WIDTH, frame.bottom, paint);
              canvas.drawRect(frame.right - ScreenRate, frame.bottom - CORNER_WIDTH,
                      frame.right, frame.bottom, paint);
              canvas.drawRect(frame.right - CORNER_WIDTH, frame.bottom - ScreenRate,
                      frame.right, frame.bottom, paint);  

            Collection<ResultPoint> currentPossible = possibleResultPoints;
            Collection<ResultPoint> currentLast = lastPossibleResultPoints;
            if (currentPossible.isEmpty()) {
                lastPossibleResultPoints = null;
            } else {
                possibleResultPoints = new HashSet<ResultPoint>(5);
                lastPossibleResultPoints = currentPossible;
                paint.setAlpha(OPAQUE);
                paint.setColor(resultPointColor);
                for (ResultPoint point : currentPossible) {
                    canvas.drawCircle(frame.left + point.getX(), frame.top
                            + point.getY(), 6.0f, paint);
                }
            }
            if (currentLast != null) {
                paint.setAlpha(OPAQUE / 2);
                paint.setColor(resultPointColor);
                for (ResultPoint point : currentLast) {
                    canvas.drawCircle(frame.left + point.getX(), frame.top
                            + point.getY(), 3.0f, paint);
                }
            }

            // Request another update at the animation interval, but only
            // repaint the laser line,
            // not the entire viewfinder mask.
            //鍙埛鏂版壂鎻忔鐨勫唴瀹癸紝鍏朵粬鍦版柟涓嶅埛鏂�
            postInvalidateDelayed(ANIMATION_DELAY, frame.left, frame.top,
                    frame.right, frame.bottom);
        }
    }

    public void drawViewfinder() {
        resultBitmap = null;
        invalidate();
    }

    /**
     * Draw a bitmap with the result points highlighted instead of the live
     * scanning display.
     *
     * @param barcode
     *            An image of the decoded barcode.
     */
    public void drawResultBitmap(Bitmap barcode) {
        resultBitmap = barcode;
        invalidate();
    }

    public void addPossibleResultPoint(ResultPoint point) {
        possibleResultPoints.add(point);
    }

}