Signal/Android
1
0
Fork 0
mirror of https://github.com/signalapp/Signal-Android.git synced 2026-04-24 10:51:27 +01:00
Code Issues Packages Projects Releases Wiki Activity

Improve handling of partially bi-directional text.

Browse Source
This commit is contained in:
Greyson Parrelli
2020-07-29 00:55:20 -04:00
parent e504ffa225
commit 8ed7fc894e
7 changed files with 108 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
app/src/main/java/org/thoughtcrime/securesms/util/GroupUtil.java
View File

@@ -125,7 +125,7 @@ public final class GroupUtil {
return description.toString();
}
String title = groupContext.getName();
String title = StringUtil.isolateBidi(groupContext.getName());
if (members != null && members.size() > 0) {
description.append("\n");

77
app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
View File

@@ -2,10 +2,12 @@ package org.thoughtcrime.securesms.util;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.text.BidiFormatter;
import com.google.android.collect.Sets;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.Set;
public final class StringUtil {
@@ -14,6 +16,27 @@ public final class StringUtil {
'\u200F', // right-to-left mark
'\u2007'); // figure space
private static final class Bidi {
/** Override text direction */
private static final Set<Integer> OVERRIDES = Sets.newHashSet("\u202a".codePointAt(0), /* LRE */
"\u202b".codePointAt(0), /* RLE */
"\u202d".codePointAt(0), /* LRO */
"\u202e".codePointAt(0) /* RLO */);
/** Set direction and isolate surrounding text */
private static final Set<Integer> ISOLATES = Sets.newHashSet("\u2066".codePointAt(0), /* LRI */
"\u2067".codePointAt(0), /* RLI */
"\u2068".codePointAt(0) /* FSI */);
/** Closes things in {@link #OVERRIDES} */
private static final int PDF = "\u202c".codePointAt(0);
/** Closes things in {@link #ISOLATES} */
private static final int PDI = "\u2069".codePointAt(0);
/** Auto-detecting isolate */
private static final int FSI = "\u2068".codePointAt(0);
}
private StringUtil() {
}
@@ -99,4 +122,58 @@ public final class StringUtil {
public static @NonNull String codePointToString(int codePoint) {
return new String(Character.toChars(codePoint));
}
/**
* Isolates bi-directional text from influencing surrounding text. You should use this whenever
* you're injecting user-generated text into a larger string.
*
* You'd think we'd be able to trust {@link BidiFormatter}, but unfortunately it just misses some
* corner cases, so here we are.
*
* The general idea is just to balance out the opening and closing codepoints, and then wrap the
* whole thing in FSI/PDI to isolate it.
*
* For more details, see:
* https://www.w3.org/International/questions/qa-bidi-unicode-controls
*/
public static @NonNull String isolateBidi(@NonNull String text) {
int overrideCount = 0;
int overrideCloseCount = 0;
int isolateCount = 0;
int isolateCloseCount = 0;
for (int i = 0, len = text.codePointCount(0, text.length()); i < len; i++) {
int codePoint = text.codePointAt(i);
if (Bidi.OVERRIDES.contains(codePoint)) {
overrideCount++;
} else if (codePoint == Bidi.PDF) {
overrideCloseCount++;
} else if (Bidi.ISOLATES.contains(codePoint)) {
isolateCount++;
} else if (codePoint == Bidi.PDI) {
isolateCloseCount++;
}
}
StringBuilder suffix = new StringBuilder();
while (overrideCount > overrideCloseCount) {
suffix.appendCodePoint(Bidi.PDF);
overrideCloseCount++;
}
while (isolateCount > isolateCloseCount) {
suffix.appendCodePoint(Bidi.FSI);
isolateCloseCount++;
}
StringBuilder out = new StringBuilder();
return out.appendCodePoint(Bidi.FSI)
.append(text)
.append(suffix)
.appendCodePoint(Bidi.PDI)
.toString();
}
}