max out emoji enlargment at 42 emojis

src/main/java/eu/siacs/conversations/ui/adapter/MessageAdapter.java

@@ -203,7 +203,7 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
 		return 4;
 	}
 
-	public int getItemViewType(Message message) {
+	private int getItemViewType(Message message) {
 		if (message.getType() == Message.TYPE_STATUS) {
 			if (DATE_SEPARATOR_BODY.equals(message.getBody())) {
 				return DATE_SEPARATOR;
@@ -222,7 +222,7 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
 		return this.getItemViewType(getItem(position));
 	}
 
-	public int getMessageTextColor(boolean onDark, boolean primary) {
+	private int getMessageTextColor(boolean onDark, boolean primary) {
 		if (onDark) {
 			return ContextCompat.getColor(activity, primary ? R.color.white : R.color.white70);
 		} else {
@@ -390,7 +390,7 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
 		viewHolder.messageBody.setText(EmojiWrapper.transform(span));
 	}
 
-	private int applyQuoteSpan(SpannableStringBuilder body, int start, int end, boolean darkBackground) {
+	private void applyQuoteSpan(SpannableStringBuilder body, int start, int end, boolean darkBackground) {
 		if (start > 1 && !"\n\n".equals(body.subSequence(start - 2, start).toString())) {
 			body.insert(start++, "\n");
 			body.setSpan(new DividerSpan(false), start - 2, start, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
@@ -404,7 +404,6 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
 				: ContextCompat.getColor(activity, R.color.green700_desaturated);
 		DisplayMetrics metrics = getContext().getResources().getDisplayMetrics();
 		body.setSpan(new QuoteSpan(color, metrics), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
-		return 0;
 	}
 
 	/**
@@ -536,7 +535,7 @@ public class MessageAdapter extends ArrayAdapter<Message> implements CopyTextVie
 					}
 				}
 			}
-			Matcher matcher = Emoticons.generatePattern(body).matcher(body);
+			Matcher matcher = Emoticons.getEmojiPattern(body).matcher(body);
 			while (matcher.find()) {
 				if (matcher.start() < matcher.end()) {
 					body.setSpan(new RelativeSizeSpan(1.2f), matcher.start(), matcher.end(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

src/main/java/eu/siacs/conversations/utils/Emoticons.java

@@ -29,8 +29,12 @@
 
 package eu.siacs.conversations.utils;
 
+import android.util.LruCache;
+
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.regex.Pattern;
 
@@ -71,12 +75,16 @@ public class Emoticons {
 			ENCLOSED_IDEOGRAPHIC_SUPPLEMENT,
 			MISC_TECHNICAL);
 
+	private static final int MAX_EMOIJS = 42;
+
 	private static final int ZWJ = 0x200D;
 	private static final int VARIATION_16 = 0xFE0F;
 	private static final int COMBINING_ENCLOSING_KEYCAP = 0x20E3;
 	private static final int BLACK_FLAG = 0x1F3F4;
 	private static final UnicodeRange FITZPATRICK = new UnicodeRange(0x1F3FB,0x1F3FF);
 
+	private static final LruCache<CharSequence,Pattern> CACHE = new LruCache<>(256);
+
 	private static List<Symbol> parse(String input) {
 		List<Symbol> symbols = new ArrayList<>();
 		Builder builder = new Builder();
@@ -99,15 +107,32 @@ public class Emoticons {
 		return symbols;
 	}
 
-	public static Pattern generatePattern(CharSequence input) {
+	public static Pattern getEmojiPattern(CharSequence input) {
-		final StringBuilder pattern = new StringBuilder();
+		Pattern pattern = CACHE.get(input);
+		if (pattern == null) {
+			pattern = generatePattern(input);
+			CACHE.put(input, pattern);
+		}
+		return pattern;
+	}
+
+	private static Pattern generatePattern(CharSequence input) {
+		final HashSet<String> emojis = new HashSet<>();
+		int i = 0;
 		for(Symbol symbol : parse(input.toString())) {
 			if (symbol instanceof Emoji) {
+				emojis.add(symbol.toString());
+				if (++i >= MAX_EMOIJS) {
+					return Pattern.compile("");
+				}
+			}
+		}
+		final StringBuilder pattern = new StringBuilder();
+		for(String emoji : emojis) {
 			if (pattern.length() != 0) {
 				pattern.append('|');
 			}
-				pattern.append(Pattern.quote(symbol.toString()));
+			pattern.append(Pattern.quote(emoji));
-			}
 		}
 		return Pattern.compile(pattern.toString());
 	}