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.settings.utils;
18 
19 import android.annotation.Nullable;
20 import android.content.Context;
21 import android.content.res.Resources;
22 import android.text.BidiFormatter;
23 import android.text.format.Formatter;
24 
25 /**
26  * Utility class to aid in formatting file sizes always with the same unit. This is modified from
27  * android.text.format.Formatter to fit this purpose.
28  */
29 public final class FileSizeFormatter {
30     public static final long KILOBYTE_IN_BYTES = 1000;
31     public static final long MEGABYTE_IN_BYTES = KILOBYTE_IN_BYTES * 1000;
32     public static final long GIGABYTE_IN_BYTES = MEGABYTE_IN_BYTES * 1000;
33 
34     /**
35      * Formats a content size to be in the form of bytes, kilobytes, megabytes, etc.
36      *
37      * <p>As of O, the prefixes are used in their standard meanings in the SI system, so kB = 1000
38      * bytes, MB = 1,000,000 bytes, etc.
39      *
40      * <p class="note">In {@link android.os.Build.VERSION_CODES#N} and earlier, powers of 1024 are
41      * used instead, with KB = 1024 bytes, MB = 1,048,576 bytes, etc.
42      *
43      * <p>If the context has a right-to-left locale, the returned string is wrapped in bidi
44      * formatting characters to make sure it's displayed correctly if inserted inside a
45      * right-to-left string. (This is useful in cases where the unit strings, like "MB", are
46      * left-to-right, but the locale is right-to-left.)
47      *
48      * @param context Context to use to load the localized units
49      * @param sizeBytes size value to be formatted, in bytes
50      * @param suffix String id for the unit suffix.
51      * @param mult Amount of bytes in the unit. * @return formatted string with the number
52      */
formatFileSize( @ullable Context context, long sizeBytes, int suffix, long mult)53     public static String formatFileSize(
54             @Nullable Context context, long sizeBytes, int suffix, long mult) {
55         if (context == null) {
56             return "";
57         }
58         final Formatter.BytesResult res =
59                 formatBytes(context.getResources(), sizeBytes, suffix, mult);
60         return BidiFormatter.getInstance()
61                 .unicodeWrap(context.getString(getFileSizeSuffix(context), res.value, res.units));
62     }
63 
getFileSizeSuffix(Context context)64     private static int getFileSizeSuffix(Context context) {
65         final Resources res = context.getResources();
66         return res.getIdentifier("fileSizeSuffix", "string", "android");
67     }
68 
69     /**
70      * A simplified version of the SettingsLib file size formatter. The primary difference is that
71      * this version always assumes it is doing a "short file size" and allows for a suffix to be
72      * provided.
73      *
74      * @param res Resources to fetch strings with.
75      * @param sizeBytes File size in bytes to format.
76      * @param suffix String id for the unit suffix.
77      * @param mult Amount of bytes in the unit.
78      */
formatBytes( Resources res, long sizeBytes, int suffix, long mult)79     private static Formatter.BytesResult formatBytes(
80             Resources res, long sizeBytes, int suffix, long mult) {
81         final boolean isNegative = (sizeBytes < 0);
82         float result = isNegative ? -sizeBytes : sizeBytes;
83         result = result / mult;
84         // Note we calculate the rounded long by ourselves, but still let String.format()
85         // compute the rounded value. String.format("%f", 0.1) might not return "0.1" due to
86         // floating point errors.
87         final int roundFactor;
88         final String roundFormat;
89         if (mult == 1) {
90             roundFactor = 1;
91             roundFormat = "%.0f";
92         } else if (result < 1) {
93             roundFactor = 100;
94             roundFormat = "%.2f";
95         } else if (result < 10) {
96             roundFactor = 10;
97             roundFormat = "%.1f";
98         } else { // 10 <= result < 100
99             roundFactor = 1;
100             roundFormat = "%.0f";
101         }
102 
103         if (isNegative) {
104             result = -result;
105         }
106         final String roundedString = String.format(roundFormat, result);
107 
108         // Note this might overflow if abs(result) >= Long.MAX_VALUE / 100, but that's like 80PB so
109         // it's okay (for now)...
110         final long roundedBytes = (((long) Math.round(result * roundFactor)) * mult / roundFactor);
111 
112         final String units = res.getString(suffix);
113 
114         return new Formatter.BytesResult(roundedString, units, roundedBytes);
115     }
116 }
117