RippleView.java

package com.yelinaung.ottofit.widget;

import android.animation.Animator;
import android.animation.ObjectAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RadialGradient;
import android.graphics.Region;
import android.graphics.Shader;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.StateListDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.Button;
import com.yelinaung.ottofit.R;

/**
 * Ripple View from https://github.com/siriscac/RippleView
 */

public class RippleView extends Button {

  private float mDownX;
  private float mDownY;
  private float mAlphaFactor;

  private float mRadius;

  private int mRippleColor;
  private boolean isAnimating = false;

  private RadialGradient mRadialGradient;
  private Paint mPaint;

  public RippleView(Context context) {
    super(context);
    init();
  }

  public RippleView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init();
    TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RippleView);
    mRippleColor = a.getColor(R.styleable.RippleView_rippleColor, mRippleColor);
    mAlphaFactor = a.getFloat(R.styleable.RippleView_alphaFactor, mAlphaFactor);
    a.recycle();
  }

  public RippleView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
    TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RippleView);
    mRippleColor = a.getColor(R.styleable.RippleView_rippleColor, mRippleColor);
    mAlphaFactor = a.getFloat(R.styleable.RippleView_alphaFactor, mAlphaFactor);
    a.recycle();
  }

  public void init() {
    mPaint = new Paint();
    mPaint.setAlpha(100);
    setRippleColor(Color.BLACK, 0.2f);
    ShapeDrawable normal = new ShapeDrawable(new RectShape());
    normal.getPaint().setColor(Color.parseColor("#00FFFFFF"));
    StateListDrawable states = new StateListDrawable();

    states.addState(new int[] { android.R.attr.state_pressed, android.R.attr.state_enabled },
        normal);
    states.addState(new int[] { android.R.attr.state_focused, android.R.attr.state_enabled },
        normal);
    states.addState(new int[] { android.R.attr.state_enabled }, normal);
    states.addState(new int[] { -android.R.attr.state_enabled }, normal);
    setBackgroundDrawable(states);
  }

  public void setRippleColor(int rippleColor, float alphaFactor) {
    this.mRippleColor = rippleColor;
    this.mAlphaFactor = alphaFactor;
  }

  @Override
  public boolean onTouchEvent(final MotionEvent event) {
    if (event.getActionMasked() == MotionEvent.ACTION_DOWN && !isAnimating) {
      mDownX = event.getX();
      mDownY = event.getY();

      ObjectAnimator radAnim = ObjectAnimator.ofFloat(this, "radius", 0, getWidth() * 3.0f);
      radAnim.setDuration(500);
      radAnim.addListener(new Animator.AnimatorListener() {
        @Override
        public void onAnimationStart(Animator animator) {
          isAnimating = true;
        }

        @Override
        public void onAnimationEnd(Animator animator) {
          setRadius(0);
          setAlpha(1);
          isAnimating = false;
        }

        @Override
        public void onAnimationCancel(Animator animator) {

        }

        @Override
        public void onAnimationRepeat(Animator animator) {

        }
      });
      radAnim.start();
    }
    return super.onTouchEvent(event);
  }

  public int adjustAlpha(int color, float factor) {
    int alpha = Math.round(Color.alpha(color) * factor);
    int red = Color.red(color);
    int green = Color.green(color);
    int blue = Color.blue(color);
    return Color.argb(alpha, red, green, blue);
  }

  public void setRadius(final float radius) {
    mRadius = radius;
    if (mRadius > 0) {
      mRadialGradient =
          new RadialGradient(mDownX, mDownY, mRadius * 3, adjustAlpha(mRippleColor, mAlphaFactor),
              mRippleColor, Shader.TileMode.MIRROR);
      mPaint.setShader(mRadialGradient);
    }
    invalidate();
  }

  private Path mPath = new Path();
  private Path mPath2 = new Path();

  @Override
  protected void onDraw(final Canvas canvas) {
    super.onDraw(canvas);

    if (isInEditMode()) {
      return;
    }

    mPath2.reset();
    mPath2.addCircle(mDownX, mDownY, mRadius, Path.Direction.CW);

    canvas.clipPath(mPath2);

    mPath.reset();
    mPath.addCircle(mDownX, mDownY, mRadius / 3, Path.Direction.CW);

    canvas.clipPath(mPath, Region.Op.INTERSECT);
    canvas.drawCircle(mDownX, mDownY, mRadius, mPaint);
  }
}