A custom ColorDrawable that can easily be implemented as a progress bar.

ProgressDrawable.java

/*
 * Copyright 2013 Andrew Neal
 *
 * 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.andrew.apollo.drawable;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;

/**
 * A custom {@link Drawable} that can easily be used as a progress bar.
 * 
 * @author Andrew Neal (andrew@seeingpixels.org)
 */
public class ProgressDrawable extends ColorDrawable {

    /** The drawable's bounds Rect */
    private final Rect mBounds = getBounds();
    /** Used to draw the progress bar */
    private final Paint mProgressPaint = new Paint();

    /** The upper range of the progress bar */
    public int max = 100;
    /** The current progress */
    public int progress;

    /**
     * Constructor for <code>ProgessDrawable</code>
     * 
     * @param color The color to use
     */
    public ProgressDrawable(int color) {
        mProgressPaint.setColor(color);
        mProgressPaint.setAntiAlias(true);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void draw(Canvas canvas) {
        final int right = mBounds.right * progress / max;
        canvas.drawRect(mBounds.left, mBounds.top, right, mBounds.bottom, mProgressPaint);
    }

    /**
     * Set the range of the progress bar, 0 - max
     * 
     * @param max The upper range of this progress bar
     */
    public void setMax(int max) {
        this.max = max;
        invalidateSelf();
    }

    /**
     * Set the current progress to the specified value
     * 
     * @param progress The new progress, between 0 and {@link #mMax}
     */
    public void setProgress(int progress) {
        this.progress = progress;
        invalidateSelf();
    }

}

ProgressDrawableExample.java

        // Initialize the ProgressDrawable
        final int bugDroid = Color.parseColor("#A4C639");
        final ProgressDrawable progressDrawable = new ProgressDrawable(bugDroid);

        // Initialize the ActionBar
        final ActionBar actionBar = getActionBar();
        actionBar.setBackgroundDrawable(progressDrawable);
        actionBar.setTitle("0%");

        // Attach a progress listener
        final SeekBar seekBar = (SeekBar) findViewById(android.R.id.progress);
        seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                // Update the ProgressDrawable
                progressDrawable.setProgress(progress);
                // Update the ActionBar title
                actionBar.setTitle(progress + "%");
            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                // Nothing to do
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
                // Nothing to do
            }
            
        });

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