Rounded frame layout

RoundedCornerLayout.java

package com.soundconcepts.mybuilder.ui.widgets;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.widget.FrameLayout;

public class RoundedCornerLayout extends FrameLayout {
  private final static float CORNER_RADIUS = 6.0f;

  private Bitmap mMaskBitmap;
  private Paint mPaint, mMaskPaint;
  private float mCornerRadius;

  public RoundedCornerLayout(Context context) {
    super(context);
    init(context, null, 0);
  }

  public RoundedCornerLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context, attrs, 0);
  }

  public RoundedCornerLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init(context, attrs, defStyle);
  }

  private void init(Context context, AttributeSet attrs, int defStyle) {
    final DisplayMetrics metrics = context.getResources().getDisplayMetrics();
    mCornerRadius = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, CORNER_RADIUS, metrics);

    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

    mMaskPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
    mMaskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));

    setWillNotDraw(false);
  }

  @Override
  public void draw(Canvas canvas) {
    final Bitmap offscreenBitmap = Bitmap.createBitmap(canvas.getWidth(), canvas.getHeight(), Bitmap.Config.ARGB_8888);
    final Canvas offscreenCanvas = new Canvas(offscreenBitmap);

    super.draw(offscreenCanvas);

    if (mMaskBitmap == null) {
      mMaskBitmap = createMask(canvas.getWidth(), canvas.getHeight());
    }

    offscreenCanvas.drawBitmap(mMaskBitmap, 0f, 0f, mMaskPaint);
    canvas.drawBitmap(offscreenBitmap, 0f, 0f, mPaint);
  }

  private Bitmap createMask(int width, int height) {
    final Bitmap mask = Bitmap.createBitmap(width, height, Bitmap.Config.ALPHA_8);
    final Canvas canvas = new Canvas(mask);

    final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.WHITE);

    canvas.drawRect(0, 0, width, height, paint);

    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
    canvas.drawRoundRect(new RectF(0, 0, width, height), mCornerRadius, mCornerRadius, paint);

    return mask;
  }
}