CountdownIndicator.java

/*
 * Copyright 2011 Google Inc. All Rights Reserved.
 *
 * 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 net.coding.program.login.auth;

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

import net.coding.program.R;

/**
 * Circular countdown indicator. The indicator is a filled arc which starts as a full circle ({@code
 * 360} degrees) and shrinks to {@code 0} degrees the less time is remaining.
 *
 * @author klyubin@google.com (Alex Klyubin)
 */
public class CountdownIndicator extends View {
    private static final int DEFAULT_COLOR = 0xff666666;
    private final Paint mRemainingSectorPaint;
    private final Paint mBorderPaint;
    /**
     * Countdown phase starting with {@code 1} when a full cycle is remaining and shrinking to
     * {@code 0} the closer the countdown is to zero.
     */
    private double mPhase;

    public CountdownIndicator(Context context) {
        this(context, null);
    }

    public CountdownIndicator(Context context, AttributeSet attrs) {
        super(context, attrs);

        int color = DEFAULT_COLOR;
        Resources.Theme theme = context.getTheme();
        TypedArray appearance = theme.obtainStyledAttributes(
                attrs, R.styleable.CountdownIndicator, 0, 0);
        if (appearance != null) {
            int n = appearance.getIndexCount();
            for (int i = 0; i < n; i++) {
                int attr = appearance.getIndex(i);

                switch (attr) {
                    case R.styleable.CountdownIndicator_indicator_color:
                        color = appearance.getColor(attr, DEFAULT_COLOR);
                        break;
                }
            }
        }

        mBorderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mBorderPaint.setStrokeWidth(0); // hairline
        mBorderPaint.setStyle(Style.STROKE);
        mBorderPaint.setColor(color);
        mRemainingSectorPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mRemainingSectorPaint.setColor(mBorderPaint.getColor());
    }

    @Override
    protected void onDraw(Canvas canvas) {
        float remainingSectorSweepAngle = (float) (mPhase * 360);
        float remainingSectorStartAngle = 270 - remainingSectorSweepAngle;

        // Draw the sector/filled arc
        // We need to leave the leftmost column and the topmost row out of the drawingRect because
        // in anti-aliased mode drawArc and drawOval use these areas for some reason.
        RectF drawingRect = new RectF(1, 1, getWidth() - 1, getHeight() - 1);
        if (remainingSectorStartAngle < 360) {
            canvas.drawArc(
                    drawingRect,
                    remainingSectorStartAngle,
                    remainingSectorSweepAngle,
                    true,
                    mRemainingSectorPaint);
        } else {
            // 360 degrees is equivalent to 0 degrees for drawArc, hence the drawOval below.
            canvas.drawOval(drawingRect, mRemainingSectorPaint);
        }

        // Draw the outer border
//        canvas.drawOval(drawingRect, mBorderPaint);
    }

    /**
     * Sets the phase of this indicator.
     *
     * @param phase phase {@code [0, 1]}: {@code 1} when the maximum amount of time is remaining,
     *              {@code 0} when no time is remaining.
     */
    public void setPhase(double phase) {
        if ((phase < 0) || (phase > 1)) {
            throw new IllegalArgumentException("phase: " + phase);
        }

        mPhase = phase;
        invalidate();
    }
}