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/*
* Copyright (C) 2008 Google Inc.
*
* 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.android.barcodes;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
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 class ViewfinderView extends View {
private static final int[] SCANNER_ALPHA = {0, 64, 128, 192, 255, 192, 128, 64};
private static final int ANIMATION_DELAY = 100;
private Paint mPaint;
private Rect mBox;
private Point[] mResultPoints;
private int mMaskColor;
private int mFrameColor;
private int mPointsColor;
private int mLaserColor;
private int mScannerAlpha;
// 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().
mPaint = new Paint();
mBox = new Rect();
Resources resources = getResources();
mMaskColor = resources.getColor(R.color.viewfinder_mask);
mFrameColor = resources.getColor(R.color.viewfinder_frame);
mPointsColor = resources.getColor(R.color.result_points);
mLaserColor = resources.getColor(R.color.viewfinder_laser);
mScannerAlpha = 0;
}
@Override
public void onDraw(Canvas canvas) {
Rect frame = CameraManager.get().getFramingRect();
int width = canvas.getWidth();
int height = canvas.getHeight();
// Draw the exterior (i.e. outside the framing rect) darkened
mPaint.setColor(mMaskColor);
mBox.set(0, 0, width, frame.top);
canvas.drawRect(mBox, mPaint);
mBox.set(0, frame.top, frame.left, frame.bottom + 1);
canvas.drawRect(mBox, mPaint);
mBox.set(frame.right + 1, frame.top, width, frame.bottom + 1);
canvas.drawRect(mBox, mPaint);
mBox.set(0, frame.bottom + 1, width, height);
canvas.drawRect(mBox, mPaint);
// Draw a two pixel solid black border inside the framing rect
mPaint.setColor(mFrameColor);
mBox.set(frame.left, frame.top, frame.right + 1, frame.top + 2);
canvas.drawRect(mBox, mPaint);
mBox.set(frame.left, frame.top + 2, frame.left + 2, frame.bottom - 1);
canvas.drawRect(mBox, mPaint);
mBox.set(frame.right - 1, frame.top, frame.right + 1, frame.bottom - 1);
canvas.drawRect(mBox, mPaint);
mBox.set(frame.left, frame.bottom - 1, frame.right + 1, frame.bottom + 1);
canvas.drawRect(mBox, mPaint);
if (mResultPoints != null) {
// Superimpose a line for 1D or dots for 2D to highlight the key features of the barcode
mPaint.setColor(mPointsColor);
if (mResultPoints.length == 2) {
mPaint.setStrokeWidth(4);
canvas.drawLine(mResultPoints[0].x, mResultPoints[0].y, mResultPoints[1].x,
mResultPoints[1].y, mPaint);
} else {
mPaint.setStrokeWidth(10);
for (int x = 0; x < mResultPoints.length; x++) {
canvas.drawPoint(mResultPoints[x].x, mResultPoints[x].y, mPaint);
}
}
} else {
// Draw a red "laser scanner" line through the middle to show decoding is active
mPaint.setColor(mLaserColor);
mPaint.setAlpha(SCANNER_ALPHA[mScannerAlpha]);
mScannerAlpha = (mScannerAlpha + 1) % SCANNER_ALPHA.length;
int middle = frame.height() / 2 + frame.top;
mBox.set(frame.left + 2, middle - 1, frame.right - 1, middle + 2);
canvas.drawRect(mBox, mPaint);
// Request another update at the animation interval, but only repaint the laser line,
// not the entire viewfinder mask.
postInvalidateDelayed(ANIMATION_DELAY, mBox.left, mBox.top, mBox.right, mBox.bottom);
}
}
public void drawViewfinder() {
mResultPoints = null;
invalidate();
}
/**
* Draw a line for 1D barcodes (which return two points) or otherwise a set of points returned
* from the decoder to indicate what we found. For efficiency, convert these to drawable
* coordinates once here.
*
* @param resultPoints An array of points from the decoder, whose coordinates are expressed
* relative to the still image from the camera.
*/
public void drawResultPoints(ResultPoint[] resultPoints) {
mResultPoints = CameraManager.get().convertResultPoints(resultPoints);
invalidate();
}
}
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