LatinIME/java/src/com/android/inputmethod/keyboard/internal/RoundedLine.java

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/*
* 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.Rect;
import android.graphics.RectF;
public final class RoundedLine {
private final RectF mArc1 = new RectF();
private final RectF mArc2 = new RectF();
private final Path mPath = new Path();
private static final double RADIAN_TO_DEGREE = 180.0d / Math.PI;
private static final double RIGHT_ANGLE = Math.PI / 2.0d;
/**
* Make a rounded line path
*
* @param p1x the x-coordinate of the start point.
* @param p1y the y-coordinate of the start point.
* @param r1 the radius at the start point
* @param p2x the x-coordinate of the end point.
* @param p2y the y-coordinate of the end point.
* @param r2 the radius at the end point
* @return an instance of {@link Path} that holds the result rounded line, or an instance of
* {@link Path} that holds an empty path if the start and end points are equal.
*/
public Path makePath(final float p1x, final float p1y, final float r1,
final float p2x, final float p2y, final float r2) {
mPath.rewind();
final double dx = p2x - p1x;
final double dy = p2y - p1y;
// Distance of the points.
final double l = Math.hypot(dx, dy);
if (Double.compare(0.0d, l) == 0) {
return mPath; // Return an empty path
}
// Angle of the line p1-p2
final double a = Math.atan2(dy, dx);
// Difference of trail cap radius.
final double dr = r2 - r1;
// Variation of angle at trail cap.
final double ar = Math.asin(dr / l);
// The start angle of trail cap arc at P1.
final double aa = a - (RIGHT_ANGLE + ar);
// The end angle of trail cap arc at P2.
final double 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);
// Closing point of arc at P1.
final float p1ax = p1x + r1 * cosa;
final float p1ay = p1y + r1 * sina;
// Opening point of arc at P1.
final float p1bx = p1x + r1 * cosb;
final float p1by = p1y + r1 * sinb;
// Opening point of arc at P2.
final float p2ax = p2x + r2 * cosa;
final float p2ay = p2y + r2 * sina;
// Closing point of arc at P2.
final float p2bx = p2x + r2 * cosb;
final float p2by = p2y + r2 * sinb;
// Start angle of the trail arcs.
final float angle = (float)(aa * RADIAN_TO_DEGREE);
final float ar2degree = (float)(ar * 2.0d * RADIAN_TO_DEGREE);
// Sweep angle of the trail arc at P1.
final float a1 = -180.0f + ar2degree;
// Sweep angle of the trail arc at P2.
final float a2 = 180.0f + ar2degree;
mArc1.set(p1x, p1y, p1x, p1y);
mArc1.inset(-r1, -r1);
mArc2.set(p2x, p2y, p2x, p2y);
mArc2.inset(-r2, -r2);
// Trail cap at P1.
mPath.moveTo(p1x, p1y);
mPath.arcTo(mArc1, angle, a1);
// Trail cap at P2.
mPath.moveTo(p2x, p2y);
mPath.arcTo(mArc2, angle, a2);
// Two trapezoids connecting P1 and P2.
mPath.moveTo(p1ax, p1ay);
mPath.lineTo(p1x, p1y);
mPath.lineTo(p1bx, p1by);
mPath.lineTo(p2bx, p2by);
mPath.lineTo(p2x, p2y);
mPath.lineTo(p2ax, p2ay);
mPath.close();
return mPath;
}
public void getBounds(final Rect outBounds) {
// Reuse mArc1 as working variable
mPath.computeBounds(mArc1, true /* unused */);
mArc1.roundOut(outBounds);
}
}