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      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      */
     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 
     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      */
     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