ScannerView.java

package com.mygeopay.wallet.ui;

/*
 * Copyright 2012-2014 the original author or authors.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import javax.annotation.Nonnull;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;

import com.mygeopay.wallet.R;
import com.google.zxing.ResultPoint;

/**
 * @author Andreas Schildbach
 */
public class ScannerView extends View
{
    private static final long LASER_ANIMATION_DELAY_MS = 100l;
    private static final int DOT_OPACITY = 0xa0;
    private static final int DOT_SIZE = 8;
    private static final int DOT_TTL_MS = 500;

    private final Paint maskPaint;
    private final Paint laserPaint;
    private final Paint dotPaint;
    private Bitmap resultBitmap;
    private final int maskColor;
    private final int resultColor;
    private final Map<ResultPoint, Long> dots = new HashMap<ResultPoint, Long>(16);
    private Rect frame, framePreview;

    public ScannerView(final Context context, final AttributeSet attrs)
    {
        super(context, attrs);

        final Resources res = getResources();
        maskColor = res.getColor(R.color.scan_mask);
        resultColor = res.getColor(R.color.scan_result_view);
        final int laserColor = res.getColor(R.color.scan_laser);
        final int dotColor = res.getColor(R.color.scan_dot);

        maskPaint = new Paint();
        maskPaint.setStyle(Style.FILL);

        laserPaint = new Paint();
        laserPaint.setColor(laserColor);
        laserPaint.setStrokeWidth(DOT_SIZE);
        laserPaint.setStyle(Style.STROKE);

        dotPaint = new Paint();
        dotPaint.setColor(dotColor);
        dotPaint.setAlpha(DOT_OPACITY);
        dotPaint.setStyle(Style.STROKE);
        dotPaint.setStrokeWidth(DOT_SIZE);
        dotPaint.setAntiAlias(true);
    }

    public void setFraming(@Nonnull final Rect frame, @Nonnull final Rect framePreview)
    {
        this.frame = frame;
        this.framePreview = framePreview;

        invalidate();
    }

    public void drawResultBitmap(@Nonnull final Bitmap bitmap)
    {
        resultBitmap = bitmap;

        invalidate();
    }

    public void addDot(@Nonnull final ResultPoint dot)
    {
        dots.put(dot, System.currentTimeMillis());

        invalidate();
    }

    @Override
    public void onDraw(final Canvas canvas)
    {
        if (frame == null)
            return;

        final long now = System.currentTimeMillis();

        final int width = canvas.getWidth();
        final int height = canvas.getHeight();

        // draw mask darkened
        maskPaint.setColor(resultBitmap != null ? resultColor : maskColor);
        canvas.drawRect(0, 0, width, frame.top, maskPaint);
        canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, maskPaint);
        canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1, maskPaint);
        canvas.drawRect(0, frame.bottom + 1, width, height, maskPaint);

        if (resultBitmap != null)
        {
            canvas.drawBitmap(resultBitmap, null, frame, maskPaint);
        }
        else
        {
            // draw red "laser scanner" to show decoding is active
            final boolean laserPhase = (now / 600) % 2 == 0;
            laserPaint.setAlpha(laserPhase ? 160 : 255);
            canvas.drawRect(frame, laserPaint);

            // draw points
            final int frameLeft = frame.left;
            final int frameTop = frame.top;
            final float scaleX = frame.width() / (float) framePreview.width();
            final float scaleY = frame.height() / (float) framePreview.height();

            for (final Iterator<Map.Entry<ResultPoint, Long>> i = dots.entrySet().iterator(); i.hasNext();)
            {
                final Map.Entry<ResultPoint, Long> entry = i.next();
                final long age = now - entry.getValue();
                if (age < DOT_TTL_MS)
                {
                    dotPaint.setAlpha((int) ((DOT_TTL_MS - age) * 256 / DOT_TTL_MS));

                    final ResultPoint point = entry.getKey();
                    canvas.drawPoint(frameLeft + (int) (point.getX() * scaleX), frameTop + (int) (point.getY() * scaleY), dotPaint);
                }
                else
                {
                    i.remove();
                }
            }

            // schedule redraw
            postInvalidateDelayed(LASER_ANIMATION_DELAY_MS);
        }
    }
}