Make RoundedLine as top level class (Step 4)

                / params.mTrailLingerDuration, 0.0f);

    }

    static final class RoundedLine {

        // Input

        // Previous point (P1) coordinates and trail radius.

        public float p1x, p1y;

        public float r1;

        // Current point (P2) coordinates and trail radius.

        public float p2x, p2y;

        public float r2;

        // Closing point of arc at P1.

        private float p1ax, p1ay;

        // Opening point of arc at P1.

        private float p1bx, p1by;

        // Opening point of arc at P2.

        private float p2ax, p2ay;

        // Closing point of arc at P2.

        private float p2bx, p2by;

        // Start angle of the trail arcs.

        private float angle;

        // Sweep angle of the trail arc at P1.

        private float a1;

        private final RectF arc1 = new RectF();

        // Sweep angle of the trail arc at P2.

        private float a2;

        private final RectF arc2 = new RectF();

        private final Path path = new Path();

        private static final float RADIAN_TO_DEGREE = (float)(180.0d / Math.PI);

        private static final float RIGHT_ANGLE = (float)(Math.PI / 2.0d);

        public Path makePath() {

            final float dx = p2x - p1x;

            final float dy = p2y - p1y;

            // Distance of the points.

            final double l = Math.hypot(dx, dy);

            if (Double.compare(0.0d, l) == 0) {

                return null;

            }

            // Angle of the line p1-p2

            final float a = (float)Math.atan2(dy, dx);

            // Difference of trail cap radius.

            final float dr = r2 - r1;

            // Variation of angle at trail cap.

            final float ar = (float)Math.asin(dr / l);

            // The start angle of trail cap arc at P1.

            final float aa = a - (RIGHT_ANGLE + ar);

            // The end angle of trail cap arc at P2.

            final float ab = a + (RIGHT_ANGLE + ar);

            final float cosa = (float)Math.cos(aa);

            final float sina = (float)Math.sin(aa);

            final float cosb = (float)Math.cos(ab);

            final float sinb = (float)Math.sin(ab);

            p1ax = p1x + r1 * cosa;

            p1ay = p1y + r1 * sina;

            p1bx = p1x + r1 * cosb;

            p1by = p1y + r1 * sinb;

            p2ax = p2x + r2 * cosa;

            p2ay = p2y + r2 * sina;

            p2bx = p2x + r2 * cosb;

            p2by = p2y + r2 * sinb;

            angle = aa * RADIAN_TO_DEGREE;

            final float ar2degree = ar * 2.0f * RADIAN_TO_DEGREE;

            a1 = -180.0f + ar2degree;

            a2 = 180.0f + ar2degree;

            arc1.set(p1x, p1y, p1x, p1y);

            arc1.inset(-r1, -r1);

            arc2.set(p2x, p2y, p2x, p2y);

            arc2.inset(-r2, -r2);

            path.rewind();

            // Trail cap at P1.

            path.moveTo(p1x, p1y);

            path.arcTo(arc1, angle, a1);

            // Trail cap at P2.

            path.moveTo(p2x, p2y);

            path.arcTo(arc2, angle, a2);

            // Two trapezoids connecting P1 and P2.

            path.moveTo(p1ax, p1ay);

            path.lineTo(p1x, p1y);

            path.lineTo(p1bx, p1by);

            path.lineTo(p2bx, p2by);

            path.lineTo(p2x, p2y);

            path.lineTo(p2ax, p2ay);

            path.close();

            return path;

        }

    }

    private final RoundedLine mRoundedLine = new RoundedLine();

    /**

/*

 * Copyright (C) 2012 The Android Open Source Project

 *

 * 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.android.inputmethod.keyboard.internal;

import android.graphics.Path;

import android.graphics.RectF;

public final class RoundedLine {

    // Start point (P1) coordinates and trail radius.

    public float p1x, p1y;

    public float r1;

    // End point (P2) coordinates and trail radius.

    public float p2x, p2y;

    public float r2;

    // Closing point of arc at P1.

    private float p1ax, p1ay;

    // Opening point of arc at P1.

    private float p1bx, p1by;

    // Opening point of arc at P2.

    private float p2ax, p2ay;

    // Closing point of arc at P2.

    private float p2bx, p2by;

    // Start angle of the trail arcs.

    private float angle;

    // Sweep angle of the trail arc at P1.

    private float a1;

    private final RectF arc1 = new RectF();

    // Sweep angle of the trail arc at P2.

    private float a2;

    private final RectF arc2 = new RectF();

    private final Path path = new Path();

    private static final float RADIAN_TO_DEGREE = (float)(180.0d / Math.PI);

    private static final float RIGHT_ANGLE = (float)(Math.PI / 2.0d);

    public Path makePath() {

        final float dx = p2x - p1x;

        final float dy = p2y - p1y;

        // Distance of the points.

        final double l = Math.hypot(dx, dy);

        if (Double.compare(0.0d, l) == 0) {

            return null;

        }

        // Angle of the line p1-p2

        final float a = (float)Math.atan2(dy, dx);

        // Difference of trail cap radius.

        final float dr = r2 - r1;

        // Variation of angle at trail cap.

        final float ar = (float)Math.asin(dr / l);

        // The start angle of trail cap arc at P1.

        final float aa = a - (RIGHT_ANGLE + ar);

        // The end angle of trail cap arc at P2.

        final float ab = a + (RIGHT_ANGLE + ar);

        final float cosa = (float)Math.cos(aa);

        final float sina = (float)Math.sin(aa);

        final float cosb = (float)Math.cos(ab);

        final float sinb = (float)Math.sin(ab);

        p1ax = p1x + r1 * cosa;

        p1ay = p1y + r1 * sina;

        p1bx = p1x + r1 * cosb;

        p1by = p1y + r1 * sinb;

        p2ax = p2x + r2 * cosa;

        p2ay = p2y + r2 * sina;

        p2bx = p2x + r2 * cosb;

        p2by = p2y + r2 * sinb;

        angle = aa * RADIAN_TO_DEGREE;

        final float ar2degree = ar * 2.0f * RADIAN_TO_DEGREE;

        a1 = -180.0f + ar2degree;

        a2 = 180.0f + ar2degree;

        arc1.set(p1x, p1y, p1x, p1y);

        arc1.inset(-r1, -r1);

        arc2.set(p2x, p2y, p2x, p2y);

        arc2.inset(-r2, -r2);

        path.rewind();

        // Trail cap at P1.

        path.moveTo(p1x, p1y);

        path.arcTo(arc1, angle, a1);

        // Trail cap at P2.

        path.moveTo(p2x, p2y);

        path.arcTo(arc2, angle, a2);

        // Two trapezoids connecting P1 and P2.

        path.moveTo(p1ax, p1ay);

        path.lineTo(p1x, p1y);

        path.lineTo(p1bx, p1by);

        path.lineTo(p2bx, p2by);

        path.lineTo(p2x, p2y);

        path.lineTo(p2ax, p2ay);

        path.close();

        return path;

    }

}

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