1 /*
2  * Copyright (C) 2016 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 
17 package com.android.launcher3.graphics;
18 
19 import android.content.Context;
20 import android.graphics.Bitmap;
21 import android.graphics.Bitmap.Config;
22 import android.graphics.BlurMaskFilter;
23 import android.graphics.BlurMaskFilter.Blur;
24 import android.graphics.Canvas;
25 import android.graphics.Paint;
26 import android.graphics.RectF;
27 
28 import com.android.launcher3.LauncherAppState;
29 import com.android.launcher3.util.Preconditions;
30 
31 /**
32  * Utility class to add shadows to bitmaps.
33  */
34 public class ShadowGenerator {
35 
36     // Percent of actual icon size
37     private static final float HALF_DISTANCE = 0.5f;
38     public static final float BLUR_FACTOR = 0.5f/48;
39 
40     // Percent of actual icon size
41     private static final float KEY_SHADOW_DISTANCE = 1f/48;
42     public static final int KEY_SHADOW_ALPHA = 61;
43 
44     public static final int AMBIENT_SHADOW_ALPHA = 30;
45 
46     private static final Object LOCK = new Object();
47     // Singleton object guarded by {@link #LOCK}
48     private static ShadowGenerator sShadowGenerator;
49 
50     private final int mIconSize;
51 
52     private final Canvas mCanvas;
53     private final Paint mBlurPaint;
54     private final Paint mDrawPaint;
55 
ShadowGenerator(Context context)56     private ShadowGenerator(Context context) {
57         mIconSize = LauncherAppState.getIDP(context).iconBitmapSize;
58         mCanvas = new Canvas();
59         mBlurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
60         mBlurPaint.setMaskFilter(new BlurMaskFilter(mIconSize * BLUR_FACTOR, Blur.NORMAL));
61         mDrawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
62     }
63 
recreateIcon(Bitmap icon)64     public synchronized Bitmap recreateIcon(Bitmap icon) {
65         int[] offset = new int[2];
66         Bitmap shadow = icon.extractAlpha(mBlurPaint, offset);
67         Bitmap result = Bitmap.createBitmap(mIconSize, mIconSize, Config.ARGB_8888);
68         mCanvas.setBitmap(result);
69 
70         // Draw ambient shadow
71         mDrawPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
72         mCanvas.drawBitmap(shadow, offset[0], offset[1], mDrawPaint);
73 
74         // Draw key shadow
75         mDrawPaint.setAlpha(KEY_SHADOW_ALPHA);
76         mCanvas.drawBitmap(shadow, offset[0], offset[1] + KEY_SHADOW_DISTANCE * mIconSize, mDrawPaint);
77 
78         // Draw the icon
79         mDrawPaint.setAlpha(255);
80         mCanvas.drawBitmap(icon, 0, 0, mDrawPaint);
81 
82         mCanvas.setBitmap(null);
83         return result;
84     }
85 
createPillWithShadow(int rectColor, int width, int height)86     public static Bitmap createPillWithShadow(int rectColor, int width, int height) {
87 
88         float shadowRadius = height * 1f / 32;
89         float shadowYOffset = height * 1f / 16;
90 
91         int radius = height / 2;
92 
93         Canvas canvas = new Canvas();
94         Paint blurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
95         blurPaint.setMaskFilter(new BlurMaskFilter(shadowRadius, Blur.NORMAL));
96 
97         int centerX = Math.round(width / 2 + shadowRadius);
98         int centerY = Math.round(radius + shadowRadius + shadowYOffset);
99         int center = Math.max(centerX, centerY);
100         int size = center * 2;
101         Bitmap result = Bitmap.createBitmap(size, size, Config.ARGB_8888);
102         canvas.setBitmap(result);
103 
104         int left = center - width / 2;
105         int top = center - height / 2;
106         int right = center + width / 2;
107         int bottom = center + height / 2;
108 
109         // Draw ambient shadow, center aligned within size
110         blurPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
111         canvas.drawRoundRect(left, top, right, bottom, radius, radius, blurPaint);
112 
113         // Draw key shadow, bottom aligned within size
114         blurPaint.setAlpha(KEY_SHADOW_ALPHA);
115         canvas.drawRoundRect(left, top + shadowYOffset, right, bottom + shadowYOffset,
116                 radius, radius, blurPaint);
117 
118         // Draw the circle
119         Paint drawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
120         drawPaint.setColor(rectColor);
121         canvas.drawRoundRect(left, top, right, bottom, radius, radius, drawPaint);
122 
123         return result;
124     }
125 
getInstance(Context context)126     public static ShadowGenerator getInstance(Context context) {
127         Preconditions.assertNonUiThread();
128         synchronized (LOCK) {
129             if (sShadowGenerator == null) {
130                 sShadowGenerator = new ShadowGenerator(context);
131             }
132         }
133         return sShadowGenerator;
134     }
135 
136     /**
137      * Returns the minimum amount by which an icon with {@param bounds} should be scaled
138      * so that the shadows do not get clipped.
139      */
getScaleForBounds(RectF bounds)140     public static float getScaleForBounds(RectF bounds) {
141         float scale = 1;
142 
143         // For top, left & right, we need same space.
144         float minSide = Math.min(Math.min(bounds.left, bounds.right), bounds.top);
145         if (minSide < BLUR_FACTOR) {
146             scale = (HALF_DISTANCE - BLUR_FACTOR) / (HALF_DISTANCE - minSide);
147         }
148 
149         float bottomSpace = BLUR_FACTOR + KEY_SHADOW_DISTANCE;
150         if (bounds.bottom < bottomSpace) {
151             scale = Math.min(scale, (HALF_DISTANCE - bottomSpace) / (HALF_DISTANCE - bounds.bottom));
152         }
153         return scale;
154     }
155 }
156