Preserve maxLength for EmojiEditText

Addresses #3388
Closes #5649
// FREEBIE

src/org/thoughtcrime/securesms/components/emoji/EmojiEditText.java

@@ -3,6 +3,7 @@ package org.thoughtcrime.securesms.components.emoji;
 import android.content.Context;
 import android.graphics.drawable.Drawable;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.support.v7.widget.AppCompatEditText;
 import android.text.InputFilter;
 import android.util.AttributeSet;
@@ -26,7 +27,7 @@ public class EmojiEditText extends AppCompatEditText {
   public EmojiEditText(Context context, AttributeSet attrs, int defStyleAttr) {
     super(context, attrs, defStyleAttr);
     if (!TextSecurePreferences.isSystemEmojiPreferred(getContext())) {
-      setFilters(new InputFilter[]{ new EmojiFilter(this) });
+      setFilters(appendEmojiFilter(this.getFilters()));
     }
   }
 
@@ -38,8 +39,24 @@ public class EmojiEditText extends AppCompatEditText {
     setSelection(start + emoji.length());
   }
 
-  @Override public void invalidateDrawable(@NonNull Drawable drawable) {
+  @Override
+  public void invalidateDrawable(@NonNull Drawable drawable) {
     if (drawable instanceof EmojiDrawable) invalidate();
     else                                   super.invalidateDrawable(drawable);
   }
+
+  private InputFilter[] appendEmojiFilter(@Nullable InputFilter[] originalFilters) {
+    InputFilter[] result;
+
+    if (originalFilters != null) {
+      result = new InputFilter[originalFilters.length + 1];
+      System.arraycopy(originalFilters, 0, result, 1, originalFilters.length);
+    } else {
+      result = new InputFilter[1];
+    }
+
+    result[0] = new EmojiFilter(this);
+
+    return result;
+  }
 }