src/com/ectrip/trips/view/ViewfinderViewHandset.java

/*
 * 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.ectrip.trips.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.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.view.View;
import com.ectrip.trips.check.R;
import com.google.zxing.ResultPoint;
/**
 * 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 ViewfinderViewHandset extends View {
	private static final String TAG = "log";
	/**
	 * 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 = 10;
	/**
	 * 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 ViewfinderViewHandset(Context context, AttributeSet attrs) {
		super(context, attrs);
		density = context.getResources().getDisplayMetrics().density;
		//将像素转换成dp
		ScreenRate = (int)(20 * 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<ResultPoint>(5);
	}
	@Override
	public void onDraw(Canvas canvas) {
		// 获取屏幕的宽和高
		int width = canvas.getWidth();
		int height = canvas.getHeight();
		Rect frame = null;
		if(width>height){
			int top=height/6;
			int left=(width-(height-top*2))/2;
			int bottom=height/6*5;
			int right=width-left;
			frame = new Rect(left,top,right,bottom);
		}else{
			int left=width/6;
			int top=(height-(width-left*2))/2;
			int right=width/6*5;
			int bottom=height-top;
			frame = new Rect(left,top,right,bottom);
		}
		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;
		}
		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;
			}
			//将icon图像转换为Bitmap对象
			Bitmap iconbit = BitmapFactory.decodeResource(getResources(), R.drawable.handset_code);
			canvas.drawBitmap(iconbit, null,frame, paint);
			canvas.drawRect(frame.left + MIDDLE_LINE_PADDING, slideTop - MIDDLE_LINE_WIDTH/2, frame.right - MIDDLE_LINE_PADDING,slideTop + MIDDLE_LINE_WIDTH/2, paint);
			//画扫描框下面的字
			paint.setColor(Color.BLACK);
			paint.setTextSize(TEXT_SIZE * density);
			paint.setAlpha(0x40);
			paint.setTypeface(Typeface.create("System", Typeface.BOLD));
			canvas.drawText(getResources().getString(R.string.scan_handset_text), frame.left, (float) (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<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);
				}
			}
			//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);
	}
}