1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
5 * except in compliance with the License. You may obtain a copy of the License at
6 *
7 *      http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the
10 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
11 * KIND, either express or implied. See the License for the specific language governing
12 * permissions and limitations under the License.
13 */
14
15package com.android.egg.octo;
16
17import android.graphics.Canvas;
18import android.graphics.Paint;
19import android.graphics.Path;
20import android.graphics.PathMeasure;
21import android.os.Debug;
22
23import java.util.Arrays;
24
25public class TaperedPathStroke {
26    static float sMinStepPx = 4f;
27    static PathMeasure pm = new PathMeasure();
28    static float[] pos = {0,0};
29    static float[] tan = {0,0};
30    static float lerp(float t, float a, float b) {
31        return a + t*(b-a);
32    }
33    public static void setMinStep(float px) {
34        sMinStepPx = px;
35    }
36
37    // it's the variable-width brush algorithm from the Markers app, basically
38    public static void drawPath(Canvas c, Path p, float r1, float r2, Paint pt) {
39        pm.setPath(p,false);
40        final float len = pm.getLength();
41        float t=0;
42        boolean last=false;
43        while (true) {
44            if (t>=len) {
45                t=len;
46                last=true;
47            }
48            pm.getPosTan(t, pos, tan);
49            float r = len > 0 ? lerp(t/len, r1, r2) : r1;
50            c.drawCircle(pos[0], pos[1], r, pt);
51            t += Math.max(r*0.25f, sMinStepPx); // walk forward 1/4 radius, not too small though
52            if (last) break;
53        }
54    }
55}
56