content: /*
   * 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.google.zxing.zxing.view;
  
  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.graphics.Typeface;
  import android.graphics.drawable.BitmapDrawable;
  import android.util.AttributeSet;
  import android.view.View;
  
  import com.example.qr_codescan.R;
  import com.google.zxing.ResultPoint;
  import com.google.zxing.zxing.camera.CameraManager;
  
  import java.util.Collection;
  import java.util.HashSet;
  
  /**
   * 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.
   *
   */
  public final class ViewfinderView extends View {
  	/**
  	 * 刷新界面的时间
  	 */
  	private static final long ANIMATION_DELAY = 10L;
  	private static final int OPAQUE = 0xFF;
  
  	/**
  	 * 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 = 5;
  	/**
  	 * 扫描框中的中间线的宽度
  	 */
  	private static final int MIDDLE_LINE_WIDTH = 6;
  
  	/**
  	 * 扫描框中的中间线的与扫描框左右的间隙
  	 */
  	private static final int MIDDLE_LINE_PADDING = 5;
  
  	/**
  	 * 中间那条线每次刷新移动的距离
  	 */
  	private static final int SPEEN_DISTANCE = 5;
  
  	/**
  	 * 手机的屏幕密度
  	 */
  	private static float density;
  	/**
  	 * 字体大小
  	 */
  	private static final int TEXT_SIZE = 16;
  	/**
  	 * 字体距离扫描框下面的距离
  	 */
  	private static final int TEXT_PADDING_TOP = 30;
  
  	/**
  	 * 画笔对象的引用
  	 */
  	private Paint paint;
  
  	/**
  	 * 中间滑动线的最顶端位置
  	 */
  	private int slideTop;
  
  	/**
  	 * 中间滑动线的最底端位置
  	 */
  	private int slideBottom;
  
  	/**
  	 * 将扫描的二维码拍下来，这里没有这个功能，暂时不考虑
  	 */
  	private Bitmap resultBitmap;
  	private final int maskColor;
  	private final int resultColor;
  
  	private final int resultPointColor;
  	private Collection<ResultPoint> possibleResultPoints;
  	private Collection<ResultPoint> lastPossibleResultPoints;
  
  	boolean isFirst;
  
  	public ViewfinderView(Context context, AttributeSet attrs) {
  		super(context, attrs);
  
  		density = context.getResources().getDisplayMetrics().density;
  		//将像素转换成dp
  		ScreenRate = (int)(15 * density);
  
  		paint = new Paint();
  		Resources resources = getResources();
  		maskColor = resources.getColor(R.color.viewfinder_mask);
  		resultColor = resources.getColor(R.color.result_view);
  
  		resultPointColor = resources.getColor(R.color.possible_result_points);
  		possibleResultPoints = new HashSet<>(5);
  	}
  
  	@Override
  	public void onDraw(Canvas canvas) {
  		//中间的扫描框，你要修改扫描框的大小，去CameraManager里面修改
  		Rect frame = CameraManager.get().getFramingRect();
  		if (frame == null) {
  			return;
  		}
  
  		//初始化中间线滑动的最上边和最下边
  		if(!isFirst){
  			isFirst = true;
  			slideTop = frame.top;
  			slideBottom = frame.bottom;
  		}
  
  		//获取屏幕的宽和高
  		int width = canvas.getWidth();
  		int height = canvas.getHeight();
  
  		paint.setColor(resultBitmap != null ? resultColor : maskColor);
  
  		//画出扫描框外面的阴影部分，共四个部分，扫描框的上面到屏幕上面，扫描框的下面到屏幕下面
  		//扫描框的左边面到屏幕左边，扫描框的右边到屏幕右边
  		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 {
  
  			//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);
  
  
  			//绘制中间的线,每次刷新界面，中间的线往下移动SPEEN_DISTANCE
  
  			slideTop += SPEEN_DISTANCE;
  			if(slideTop >= frame.bottom){
  				slideTop = frame.top;
  			}
  			Rect lineRect = new Rect();
  			lineRect.left = frame.left;
  			lineRect.right = frame.right;
  			lineRect.top = slideTop;
  			lineRect.bottom = slideTop + 18;
  			canvas.drawBitmap(((BitmapDrawable)(getResources().getDrawable(R.drawable.qrcode_scan_line))).getBitmap(), null, lineRect, paint);
  
  			//画扫描框下面的字
  			paint.setColor(Color.WHITE);
  			paint.setTextSize(TEXT_SIZE * density);
  			paint.setAlpha(0x40);
  			paint.setTypeface(Typeface.create("System", Typeface.BOLD));
  			String text = getResources().getString(R.string.scan_text);
  			float textWidth = paint.measureText(text);
  
  			canvas.drawText(text, (width - textWidth)/2, frame.bottom + (float)TEXT_PADDING_TOP *density, paint);
  
  			Collection<ResultPoint> currentPossible = possibleResultPoints;
  			Collection<ResultPoint> currentLast = lastPossibleResultPoints;
  			if (currentPossible.isEmpty()) {
  				lastPossibleResultPoints = null;
  			} else {
  				possibleResultPoints = new HashSet<>(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);
  				}
  			}
  
  			//只刷新扫描框的内容，其他地方不刷新
  			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);
  	}
  
  }