DeltaSpan.java

/*
 * Copyright (c) 2011, 2012 Roberto Tyley
 *
 * This file is part of 'Agit' - an Android Git client.
 *
 * Agit 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.
 *
 * Agit 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/ .
 */

package com.madgag.agit.diff;

import static java.lang.Math.max;
import static java.lang.Math.round;
import android.text.TextPaint;
import android.text.style.MetricAffectingSpan;

public class DeltaSpan extends MetricAffectingSpan {

    private final static int insertColour = 0x00c2ffc2, deleteColour = 0x00FFE6E6;

    private final float magnitude;
    private final int alpha;
    private final boolean insertNotDelete;

    public DeltaSpan(boolean insertNotDelete, float progress) {
        this.insertNotDelete = insertNotDelete;
        this.magnitude = max(0.01f, (insertNotDelete ? progress : (1 - progress))); // TODO max is HACK!

        alpha = round(magnitude * 0xff);
    }

    public int describeContents() {
        return 0;
    }

    @Override
    public void updateDrawState(TextPaint textPaint) {
        textPaint.setTextSize(textPaint.getTextSize() * magnitude);
        textPaint.setAlpha(alpha);
        textPaint.bgColor = (insertNotDelete ? insertColour : deleteColour) + (alpha << 24);
    }

    @Override
    public void updateMeasureState(TextPaint ds) {
        ds.setTextSize(ds.getTextSize() * magnitude);
    }
}