1 /*
2  * Copyright (C) 2017 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.util;
18 
19 import android.content.Context;
20 import android.content.res.TypedArray;
21 import android.graphics.Color;
22 import android.graphics.ColorMatrix;
23 import android.view.ContextThemeWrapper;
24 
25 /**
26  * Various utility methods associated with theming.
27  */
28 public class Themes {
29 
getColorAccent(Context context)30     public static int getColorAccent(Context context) {
31         return getAttrColor(context, android.R.attr.colorAccent);
32     }
33 
getColorPrimary(Context context, int theme)34     public static int getColorPrimary(Context context, int theme) {
35         return getAttrColor(new ContextThemeWrapper(context, theme), android.R.attr.colorPrimary);
36     }
37 
getAttrColor(Context context, int attr)38     public static int getAttrColor(Context context, int attr) {
39         TypedArray ta = context.obtainStyledAttributes(new int[]{attr});
40         int colorAccent = ta.getColor(0, 0);
41         ta.recycle();
42         return colorAccent;
43     }
44 
45     /**
46      * Returns the alpha corresponding to the theme attribute {@param attr}, in the range [0, 255].
47      */
getAlpha(Context context, int attr)48     public static int getAlpha(Context context, int attr) {
49         TypedArray ta = context.obtainStyledAttributes(new int[]{attr});
50         float alpha = ta.getFloat(0, 0);
51         ta.recycle();
52         return (int) (255 * alpha + 0.5f);
53     }
54 
55     /**
56      * Scales a color matrix such that, when applied to color R G B A, it produces R' G' B' A' where
57      * R' = r * R
58      * G' = g * G
59      * B' = b * B
60      * A' = a * A
61      *
62      * The matrix will, for instance, turn white into r g b a, and black will remain black.
63      *
64      * @param color The color r g b a
65      * @param target The ColorMatrix to scale
66      */
setColorScaleOnMatrix(int color, ColorMatrix target)67     public static void setColorScaleOnMatrix(int color, ColorMatrix target) {
68         target.setScale(Color.red(color) / 255f, Color.green(color) / 255f,
69                 Color.blue(color) / 255f, Color.alpha(color) / 255f);
70     }
71 }
72