Simplify text direction

app/src/main/java/eu/faircode/email/Helper.java

@@ -957,31 +957,6 @@ public class Helper {
     }
     // https://issuetracker.google.com/issues/37054851
 
-    static boolean isRtl(String text) {
-        if (TextUtils.isEmpty(text))
-            return false;
-
-        int rtl = 0;
-        int ltr = 0;
-        for (int i = 0; i < text.length(); i++)
-            switch (Character.getDirectionality(text.charAt(i))) {
-                case java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT:
-                case java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT_ARABIC:
-                case java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT_EMBEDDING:
-                case java.lang.Character.DIRECTIONALITY_RIGHT_TO_LEFT_OVERRIDE:
-                    rtl++;
-                    break;
-
-                case java.lang.Character.DIRECTIONALITY_LEFT_TO_RIGHT:
-                case java.lang.Character.DIRECTIONALITY_LEFT_TO_RIGHT_EMBEDDING:
-                case java.lang.Character.DIRECTIONALITY_LEFT_TO_RIGHT_OVERRIDE:
-                    ltr++;
-                    break;
-            }
-
-        return (rtl > ltr);
-    }
-
     static DateFormat getTimeInstance(Context context) {
         return getTimeInstance(context, SimpleDateFormat.MEDIUM);
     }

app/src/main/java/eu/faircode/email/HtmlHelper.java

@@ -36,6 +36,7 @@ import android.text.Layout;
 import android.text.Spannable;
 import android.text.SpannableStringBuilder;
 import android.text.Spanned;
+import android.text.TextDirectionHeuristics;
 import android.text.TextPaint;
 import android.text.TextUtils;
 import android.text.style.AlignmentSpan;
@@ -2260,7 +2261,7 @@ public class HtmlHelper {
                                 case "text-align":
                                     // https://developer.mozilla.org/en-US/docs/Web/CSS/text-align
                                     Layout.Alignment alignment = null;
-                                    boolean rtl = Helper.isRtl(ssb.subSequence(start, ssb.length()).toString());
+                                    boolean rtl = TextDirectionHeuristics.FIRSTSTRONG_LTR.isRtl(ssb, start, ssb.length() - start);
                                     switch (value) {
                                         case "left":
                                         case "start":