1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License
15 */
16
17package android.support.wearable.view;
18
19import android.animation.ObjectAnimator;
20import android.animation.TimeInterpolator;
21import android.animation.ValueAnimator;
22import android.annotation.TargetApi;
23import android.graphics.Canvas;
24import android.graphics.ColorFilter;
25import android.graphics.Paint;
26import android.graphics.PixelFormat;
27import android.graphics.RectF;
28import android.graphics.drawable.Drawable;
29import android.os.Build;
30import android.util.Property;
31import android.view.animation.LinearInterpolator;
32
33/**
34 * Drawable for showing an indeterminate progress indicator.
35 *
36 * TODO: When Material progress drawable is available in the support library stop using this.
37 *
38 * @hide
39 */
40@TargetApi(Build.VERSION_CODES.KITKAT_WATCH)
41class ProgressDrawable extends Drawable {
42
43    private static Property<ProgressDrawable, Integer> LEVEL =
44            new Property<ProgressDrawable, Integer>(Integer.class, "level") {
45        @Override
46        public Integer get(ProgressDrawable drawable) {
47            return drawable.getLevel();
48        }
49
50        @Override
51        public void set(ProgressDrawable drawable, Integer value) {
52            drawable.setLevel(value);
53            drawable.invalidateSelf();
54        }
55    };
56    /** Max level for a level drawable, as specified in developer docs for {@link Drawable}. */
57    private static final int MAX_LEVEL = 10000;
58
59    /** How many different sections are there, five gives us the material style star. **/
60    private static final int NUMBER_OF_SEGMENTS = 5;
61
62    private static final int LEVELS_PER_SEGMENT = MAX_LEVEL / NUMBER_OF_SEGMENTS;
63    private static final float STARTING_ANGLE = -90f;
64    private static final long ANIMATION_DURATION = 6000;
65    private static final int FULL_CIRCLE = 360;
66    private static final int MAX_SWEEP = 306;
67    private static final int CORRECTION_ANGLE = FULL_CIRCLE - MAX_SWEEP;
68    /** How far through each cycle does the bar stop growing and start shrinking, half way. **/
69    private static final float GROW_SHRINK_RATIO = 0.5f;
70    // TODO: replace this with BakedBezierInterpolator when its available in support library.
71    private static final TimeInterpolator mInterpolator = Gusterpolator.INSTANCE;
72
73    private final RectF mInnerCircleBounds = new RectF();
74    private final Paint mPaint = new Paint();
75    private final ObjectAnimator mAnimator;
76    private float mCircleBorderWidth;
77    private int mCircleBorderColor;
78
79    public ProgressDrawable() {
80        mPaint.setAntiAlias(true);
81        mPaint.setStyle(Paint.Style.STROKE);
82        mAnimator = ObjectAnimator.ofInt(this, LEVEL, 0, MAX_LEVEL);
83        mAnimator.setRepeatCount(ValueAnimator.INFINITE);
84        mAnimator.setRepeatMode(ValueAnimator.RESTART);
85        mAnimator.setDuration(ANIMATION_DURATION);
86        mAnimator.setInterpolator(new LinearInterpolator());
87    }
88
89    public void setRingColor(int color) {
90        mCircleBorderColor = color;
91    }
92
93    public void setRingWidth(float width) {
94        mCircleBorderWidth = width;
95    }
96
97    public void startAnimation() {
98        mAnimator.start();
99    }
100
101    public void stopAnimation() {
102        mAnimator.cancel();
103    }
104
105    @Override
106    public void draw(Canvas canvas) {
107        canvas.save();
108        mInnerCircleBounds.set(getBounds());
109        mInnerCircleBounds.inset(mCircleBorderWidth / 2.0f, mCircleBorderWidth / 2.0f);
110        mPaint.setStrokeWidth(mCircleBorderWidth);
111        mPaint.setColor(mCircleBorderColor);
112
113        float sweepAngle = FULL_CIRCLE;
114        boolean growing = false;
115        float correctionAngle = 0;
116        int level = getLevel();
117
118        int currentSegment = level / LEVELS_PER_SEGMENT;
119        int offset = currentSegment * LEVELS_PER_SEGMENT;
120        float progress = (level - offset) / (float) LEVELS_PER_SEGMENT;
121
122        growing = progress < GROW_SHRINK_RATIO;
123        correctionAngle = CORRECTION_ANGLE * progress;
124
125        if (growing) {
126            sweepAngle = MAX_SWEEP * mInterpolator.getInterpolation(
127                    lerpInv(0f, GROW_SHRINK_RATIO, progress));
128        } else {
129            sweepAngle = MAX_SWEEP * (1.0f - mInterpolator.getInterpolation(
130                    lerpInv(GROW_SHRINK_RATIO, 1.0f, progress)));
131        }
132
133        sweepAngle = Math.max(1, sweepAngle);
134
135        canvas.rotate(
136                level * (1.0f / MAX_LEVEL) * 2 * FULL_CIRCLE + STARTING_ANGLE + correctionAngle,
137                mInnerCircleBounds.centerX(),
138                mInnerCircleBounds.centerY());
139        canvas.drawArc(mInnerCircleBounds,
140                growing ? 0 : MAX_SWEEP - sweepAngle,
141                sweepAngle,
142                false,
143                mPaint);
144        canvas.restore();
145    }
146
147    @Override
148    public void setAlpha(int i) {
149        // Not supported.
150    }
151
152    @Override
153    public void setColorFilter(ColorFilter colorFilter) {
154        // Not supported.
155    }
156
157    @Override
158    public int getOpacity() {
159        return PixelFormat.OPAQUE;
160    }
161
162    @Override
163    protected boolean onLevelChange(int level) {
164        return true; // Changing the level of this drawable does change its appearance.
165    }
166
167    /**
168     * Returns the interpolation scalar (s) that satisfies the equation:
169     * {@code value = }lerp(a, b, s)
170     *
171     * <p>If {@code a == b}, then this function will return 0.
172     */
173    private static float lerpInv(float a, float b, float value) {
174        return a != b ? ((value - a) / (b - a)) : 0.0f;
175    }
176}
177