Android 二维码扫描框 加四个角及中间横线自动下滑

/*
* 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);
}

}