1/*
2 * Copyright (C) 2008 ZXing authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.zxing.client.android;
18
19import com.google.zxing.ResultPoint;
20import com.google.zxing.client.android.camera.CameraManager;
21
22import android.content.Context;
23import android.content.res.Resources;
24import android.graphics.Bitmap;
25import android.graphics.Canvas;
26import android.graphics.Paint;
27import android.graphics.Rect;
28import android.util.AttributeSet;
29import android.view.View;
30
31import java.util.ArrayList;
32import java.util.List;
33
34/**
35 * This view is overlaid on top of the camera preview. It adds the viewfinder rectangle and partial
36 * transparency outside it, as well as the laser scanner animation and result points.
37 *
38 * @author dswitkin@google.com (Daniel Switkin)
39 */
40public final class ViewfinderView extends View {
41
42  private static final int[] SCANNER_ALPHA = {0, 64, 128, 192, 255, 192, 128, 64};
43  private static final long ANIMATION_DELAY = 80L;
44  private static final int CURRENT_POINT_OPACITY = 0xA0;
45  private static final int MAX_RESULT_POINTS = 20;
46  private static final int POINT_SIZE = 6;
47
48  private CameraManager cameraManager;
49  private final Paint paint;
50  private Bitmap resultBitmap;
51  private final int maskColor;
52  private final int resultColor;
53  private final int frameColor;
54  private final int laserColor;
55  private final int resultPointColor;
56  private int scannerAlpha;
57  private List<ResultPoint> possibleResultPoints;
58  private List<ResultPoint> lastPossibleResultPoints;
59
60  // This constructor is used when the class is built from an XML resource.
61  public ViewfinderView(Context context, AttributeSet attrs) {
62    super(context, attrs);
63
64    // Initialize these once for performance rather than calling them every time in onDraw().
65    paint = new Paint(Paint.ANTI_ALIAS_FLAG);
66    Resources resources = getResources();
67    maskColor = resources.getColor(R.color.viewfinder_mask);
68    resultColor = resources.getColor(R.color.result_view);
69    frameColor = resources.getColor(R.color.viewfinder_frame);
70    laserColor = resources.getColor(R.color.viewfinder_laser);
71    resultPointColor = resources.getColor(R.color.possible_result_points);
72    scannerAlpha = 0;
73    possibleResultPoints = new ArrayList<ResultPoint>(5);
74    lastPossibleResultPoints = null;
75  }
76
77  public void setCameraManager(CameraManager cameraManager) {
78    this.cameraManager = cameraManager;
79  }
80
81  @Override
82  public void onDraw(Canvas canvas) {
83    Rect frame = cameraManager.getFramingRect();
84    if (frame == null) {
85      return;
86    }
87    int width = canvas.getWidth();
88    int height = canvas.getHeight();
89
90    // Draw the exterior (i.e. outside the framing rect) darkened
91    paint.setColor(resultBitmap != null ? resultColor : maskColor);
92    canvas.drawRect(0, 0, width, frame.top, paint);
93    canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, paint);
94    canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1, paint);
95    canvas.drawRect(0, frame.bottom + 1, width, height, paint);
96
97    if (resultBitmap != null) {
98      // Draw the opaque result bitmap over the scanning rectangle
99      paint.setAlpha(CURRENT_POINT_OPACITY);
100      canvas.drawBitmap(resultBitmap, null, frame, paint);
101    } else {
102
103      // Draw a two pixel solid black border inside the framing rect
104      paint.setColor(frameColor);
105      canvas.drawRect(frame.left, frame.top, frame.right + 1, frame.top + 2, paint);
106      canvas.drawRect(frame.left, frame.top + 2, frame.left + 2, frame.bottom - 1, paint);
107      canvas.drawRect(frame.right - 1, frame.top, frame.right + 1, frame.bottom - 1, paint);
108      canvas.drawRect(frame.left, frame.bottom - 1, frame.right + 1, frame.bottom + 1, paint);
109
110      // Draw a red "laser scanner" line through the middle to show decoding is active
111      paint.setColor(laserColor);
112      paint.setAlpha(SCANNER_ALPHA[scannerAlpha]);
113      scannerAlpha = (scannerAlpha + 1) % SCANNER_ALPHA.length;
114      int middle = frame.height() / 2 + frame.top;
115      canvas.drawRect(frame.left + 2, middle - 1, frame.right - 1, middle + 2, paint);
116
117      Rect previewFrame = cameraManager.getFramingRectInPreview();
118      float scaleX = frame.width() / (float) previewFrame.width();
119      float scaleY = frame.height() / (float) previewFrame.height();
120
121      List<ResultPoint> currentPossible = possibleResultPoints;
122      List<ResultPoint> currentLast = lastPossibleResultPoints;
123      int frameLeft = frame.left;
124      int frameTop = frame.top;
125      if (currentPossible.isEmpty()) {
126        lastPossibleResultPoints = null;
127      } else {
128        possibleResultPoints = new ArrayList<ResultPoint>(5);
129        lastPossibleResultPoints = currentPossible;
130        paint.setAlpha(CURRENT_POINT_OPACITY);
131        paint.setColor(resultPointColor);
132        synchronized (currentPossible) {
133          for (ResultPoint point : currentPossible) {
134            canvas.drawCircle(frameLeft + (int) (point.getX() * scaleX),
135                              frameTop + (int) (point.getY() * scaleY),
136                              POINT_SIZE, paint);
137          }
138        }
139      }
140      if (currentLast != null) {
141        paint.setAlpha(CURRENT_POINT_OPACITY / 2);
142        paint.setColor(resultPointColor);
143        synchronized (currentLast) {
144          for (ResultPoint point : currentLast) {
145            canvas.drawCircle(frameLeft + (int) (point.getX() * scaleX),
146                              frameTop + (int) (point.getY() * scaleY),
147                              POINT_SIZE / 2, paint);
148          }
149        }
150      }
151
152      // Request another update at the animation interval, but only repaint the laser line,
153      // not the entire viewfinder mask.
154      postInvalidateDelayed(ANIMATION_DELAY,
155                            frame.left - POINT_SIZE,
156                            frame.top - POINT_SIZE,
157                            frame.right + POINT_SIZE,
158                            frame.bottom + POINT_SIZE);
159    }
160  }
161
162  public void drawViewfinder() {
163    Bitmap resultBitmap = this.resultBitmap;
164    this.resultBitmap = null;
165    if (resultBitmap != null) {
166      resultBitmap.recycle();
167    }
168    invalidate();
169  }
170
171  /**
172   * Draw a bitmap with the result points highlighted instead of the live scanning display.
173   *
174   * @param barcode An image of the decoded barcode.
175   */
176  public void drawResultBitmap(Bitmap barcode) {
177    resultBitmap = barcode;
178    invalidate();
179  }
180
181  public void addPossibleResultPoint(ResultPoint point) {
182    List<ResultPoint> points = possibleResultPoints;
183    synchronized (point) {
184      points.add(point);
185      int size = points.size();
186      if (size > MAX_RESULT_POINTS) {
187        // trim it
188        points.subList(0, size - MAX_RESULT_POINTS / 2).clear();
189      }
190    }
191  }
192
193}
194