Android Open Source - ParticlePlay Alpha Pattern Drawable

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Back to project page ParticlePlay.
License

The source code is released under:
GNU General Public License
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Java Source Code

package com.droidinteractive.particleplay.preferences;
/*//from  w  ww  .  j ava 2  s . c o m
 * Copyright (c) 2010 Ragdoll Games
 * Copyright (c) 2010-2014 Droid Interactive
 * 
 * This file is part of Particle Play.
 * 
 * Particle Play 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.
 * 
 * Particle Play 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 Particle Play. If not, see <http://www.gnu.org/licenses/>.
 */
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;

/**
 * This drawable that draws a simple white and gray chessboard pattern.
 * It's pattern you will often see as a background behind a
 * partly transparent image in many applications.
 */
public class AlphaPatternDrawable extends Drawable {

  private int mRectangleSize = 10;

  private Paint mPaint = new Paint();
  private Paint mPaintWhite = new Paint();
  private Paint mPaintGray = new Paint();

  private int numRectanglesHorizontal;
  private int numRectanglesVertical;

  /**
   * Bitmap in which the pattern will be cahched.
   */
  private Bitmap    mBitmap;

  public AlphaPatternDrawable(int rectangleSize) {
    mRectangleSize = rectangleSize;
    mPaintWhite.setColor(0xffffffff);
    mPaintGray.setColor(0xffcbcbcb);
  }

  @Override
  public void draw(Canvas canvas) {
    canvas.drawBitmap(mBitmap, null, getBounds(), mPaint);
  }

  @Override
  public int getOpacity() {
    return 0;
  }

  @Override
  public void setAlpha(int alpha) {
    throw new UnsupportedOperationException("Alpha is not supported by this drawwable.");
  }

  @Override
  public void setColorFilter(ColorFilter cf) {
    throw new UnsupportedOperationException("ColorFilter is not supported by this drawwable.");
  }

  @Override
  protected void onBoundsChange(Rect bounds) {
    super.onBoundsChange(bounds);

    int height = bounds.height();
    int width = bounds.width();

    numRectanglesHorizontal = (int) Math.ceil((width / mRectangleSize));
    numRectanglesVertical = (int) Math.ceil(height / mRectangleSize);

    generatePatternBitmap();

  }

  /**
   * This will generate a bitmap with the pattern
   * as big as the rectangle we were allow to draw on.
   * We do this to chache the bitmap so we don't need to
   * recreate it each time draw() is called since it
   * takes a few milliseconds.
   */
  private void generatePatternBitmap(){

    if(getBounds().width() <= 0 || getBounds().height() <= 0){
      return;
    }
    
    mBitmap = Bitmap.createBitmap(getBounds().width(), getBounds().height(), Config.ARGB_8888);
    Canvas canvas = new Canvas(mBitmap);

    Rect r = new Rect();
    boolean verticalStartWhite = true;
    for (int i = 0; i <= numRectanglesVertical; i++) {

      boolean isWhite = verticalStartWhite;
      for (int j = 0; j <= numRectanglesHorizontal; j++) {

        r.top = i * mRectangleSize;
        r.left = j * mRectangleSize;
        r.bottom = r.top + mRectangleSize;
        r.right = r.left + mRectangleSize;

        canvas.drawRect(r, isWhite ? mPaintWhite : mPaintGray);

        isWhite = !isWhite;
      }

      verticalStartWhite = !verticalStartWhite;

    }

  }

}
Java Source Code List
