Do not allow emoji in image editing if device doesn't support it.

app/src/main/java/org/thoughtcrime/securesms/components/emoji/EmojiUtil.java

@@ -18,6 +18,7 @@ import java.util.regex.Pattern;
 
 public final class EmojiUtil {
   private static final Pattern EMOJI_PATTERN = Pattern.compile("^(?:(?:[\u00a9\u00ae\u203c\u2049\u2122\u2139\u2194-\u2199\u21a9-\u21aa\u231a-\u231b\u2328\u23cf\u23e9-\u23f3\u23f8-\u23fa\u24c2\u25aa-\u25ab\u25b6\u25c0\u25fb-\u25fe\u2600-\u2604\u260e\u2611\u2614-\u2615\u2618\u261d\u2620\u2622-\u2623\u2626\u262a\u262e-\u262f\u2638-\u263a\u2648-\u2653\u2660\u2663\u2665-\u2666\u2668\u267b\u267f\u2692-\u2694\u2696-\u2697\u2699\u269b-\u269c\u26a0-\u26a1\u26aa-\u26ab\u26b0-\u26b1\u26bd-\u26be\u26c4-\u26c5\u26c8\u26ce-\u26cf\u26d1\u26d3-\u26d4\u26e9-\u26ea\u26f0-\u26f5\u26f7-\u26fa\u26fd\u2702\u2705\u2708-\u270d\u270f\u2712\u2714\u2716\u271d\u2721\u2728\u2733-\u2734\u2744\u2747\u274c\u274e\u2753-\u2755\u2757\u2763-\u2764\u2795-\u2797\u27a1\u27b0\u27bf\u2934-\u2935\u2b05-\u2b07\u2b1b-\u2b1c\u2b50\u2b55\u3030\u303d\u3297\u3299\ud83c\udc04\ud83c\udccf\ud83c\udd70-\ud83c\udd71\ud83c\udd7e-\ud83c\udd7f\ud83c\udd8e\ud83c\udd91-\ud83c\udd9a\ud83c\ude01-\ud83c\ude02\ud83c\ude1a\ud83c\ude2f\ud83c\ude32-\ud83c\ude3a\ud83c\ude50-\ud83c\ude51\u200d\ud83c\udf00-\ud83d\uddff\ud83d\ude00-\ud83d\ude4f\ud83d\ude80-\ud83d\udeff\ud83e\udd00-\ud83e\uddff\udb40\udc20-\udb40\udc7f]|\u200d[\u2640\u2642]|[\ud83c\udde6-\ud83c\uddff]{2}|.[\u20e0\u20e3\ufe0f]+)+)+$");
+  private static final String  EMOJI_REGEX   = "[^\\p{L}\\p{M}\\p{N}\\p{P}\\p{Z}\\p{Cf}\\p{Cs}\\s]";
 
   private EmojiUtil() {}
 
@@ -84,4 +85,12 @@ public final class EmojiUtil {
 
     return (candidates != null && candidates.size() > 0) || EMOJI_PATTERN.matcher(text).matches();
   }
+
+  public static String stripEmoji(@Nullable String text) {
+    if (text == null) {
+      return text;
+    }
+
+    return text.replaceAll(EMOJI_REGEX, "");
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/scribbles/ImageEditorFragment.java

@@ -29,10 +29,12 @@ import com.bumptech.glide.request.RequestListener;
 import com.bumptech.glide.request.target.Target;
 import com.google.android.material.dialog.MaterialAlertDialogBuilder;
 
+import org.signal.core.util.FontUtil;
 import org.signal.core.util.concurrent.SignalExecutors;
 import org.signal.core.util.logging.Log;
 import org.signal.imageeditor.core.Bounds;
 import org.signal.imageeditor.core.ColorableRenderer;
+import org.signal.imageeditor.core.HiddenEditText;
 import org.signal.imageeditor.core.ImageEditorView;
 import org.signal.imageeditor.core.Renderer;
 import org.signal.imageeditor.core.SelectableRenderer;
@@ -44,6 +46,7 @@ import org.signal.imageeditor.core.renderers.MultiLineTextRenderer;
 import org.signal.libsignal.protocol.util.Pair;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.animation.ResizeAnimation;
+import org.thoughtcrime.securesms.components.emoji.EmojiUtil;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
 import org.thoughtcrime.securesms.fonts.FontTypefaceProvider;
 import org.thoughtcrime.securesms.keyvalue.SignalStore;
@@ -78,6 +81,8 @@ public final class ImageEditorFragment extends Fragment implements ImageEditorHu
 
   private static final String TAG = Log.tag(ImageEditorFragment.class);
 
+  public static final boolean CAN_RENDER_EMOJI = FontUtil.canRenderEmojiAtFontSize(1024);
+
   private static final float PORTRAIT_ASPECT_RATIO  = 9 / 16f;
 
   private static final String KEY_IMAGE_URI = "image_uri";
@@ -220,6 +225,9 @@ public final class ImageEditorFragment extends Fragment implements ImageEditorHu
     imageEditorView = view.findViewById(R.id.image_editor_view);
 
     imageEditorView.setTypefaceProvider(new FontTypefaceProvider());
+    if (!CAN_RENDER_EMOJI) {
+      imageEditorView.addTextInputFilter(new RemoveEmojiTextFilter());
+    }
 
     int width = getResources().getDisplayMetrics().widthPixels;
     int height = (int) ((16 / 9f) * width);

app/src/main/java/org/thoughtcrime/securesms/scribbles/RemoveEmojiTextFilter.java

@@ -0,0 +1,13 @@
+package org.thoughtcrime.securesms.scribbles;
+
+import androidx.annotation.NonNull;
+
+import org.signal.imageeditor.core.HiddenEditText;
+import org.thoughtcrime.securesms.components.emoji.EmojiUtil;
+
+class RemoveEmojiTextFilter implements HiddenEditText.TextFilter {
+  @Override
+  public String filter(@NonNull String text) {
+    return EmojiUtil.stripEmoji(text);
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/scribbles/TextEntryDialogFragment.kt

@@ -33,6 +33,9 @@ class TextEntryDialogFragment : KeyboardEntryDialogFragment(R.layout.v2_media_im
     controller = requireListener()
 
     hiddenTextEntry = HiddenEditText(requireContext())
+    if (!ImageEditorFragment.CAN_RENDER_EMOJI) {
+      hiddenTextEntry.addTextFilter(RemoveEmojiTextFilter())
+    }
     (view as ViewGroup).addView(hiddenTextEntry)
 
     view.setOnClickListener {

core-util/src/main/java/org/signal/core/util/FontUtil.kt

@@ -0,0 +1,40 @@
+package org.signal.core.util
+
+import android.graphics.Bitmap
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.graphics.PorterDuff
+import kotlin.math.abs
+
+
+object FontUtil {
+  private const val SAMPLE_EMOJI = "\uD83C\uDF0D" // 🌍
+
+  /**
+   * Certain platforms cannot render emoji above a certain font size.
+   *
+   * This will attempt to render an emoji at the specified font size and tell you if it's possible.
+   * It does this by rendering an emoji into a 1x1 bitmap and seeing if the resulting pixel is non-transparent.
+   *
+   * https://stackoverflow.com/a/50988748
+   */
+  @JvmStatic
+  fun canRenderEmojiAtFontSize(size: Float): Boolean {
+    val bitmap: Bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888)
+    val canvas = Canvas(bitmap)
+    val paint = Paint()
+
+    paint.textSize = size
+    paint.textAlign = Paint.Align.CENTER
+
+    val ascent: Float = abs(paint.ascent())
+    val descent: Float = abs(paint.descent())
+    val halfHeight = (ascent + descent) / 2.0f
+
+    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)
+    canvas.drawText(SAMPLE_EMOJI, 0.5f, 0.5f + halfHeight - descent, paint)
+
+    return bitmap.getPixel(0, 0) != 0
+  }
+}

core-util/src/main/java/org/signal/core/util/ListUtil.java

@@ -3,7 +3,9 @@ package org.signal.core.util;
 import androidx.annotation.NonNull;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
+import java.util.stream.Stream;
 
 public final class ListUtil {
   private ListUtil() {}
@@ -18,4 +20,15 @@ public final class ListUtil {
 
     return chunks;
   }
+
+  @SafeVarargs
+  public static <T> List<T> concat(Collection<T>... items) {
+    final List<T> concat = new ArrayList<>(Stream.of(items).map(Collection::size).reduce(0, Integer::sum));
+
+    for (Collection<T> list : items) {
+      concat.addAll(list);
+    }
+
+    return concat;
+  }
 }

image-editor/app/build.gradle

@@ -35,6 +35,7 @@ dependencies {
     implementation libs.androidx.core.ktx
     implementation libs.androidx.appcompat
     implementation libs.material.material
+    implementation project(':core-util')
     implementation project(':image-editor')
 
     implementation libs.glide.glide

image-editor/app/src/main/java/org/signal/imageeditor/app/MainActivity.java

@@ -70,6 +70,8 @@ public final class MainActivity extends AppCompatActivity {
 
     imageEditorView = findViewById(R.id.image_editor);
 
+    imageEditorView.setTypefaceProvider(typefaceProvider);
+
     imageEditorView.setUndoRedoStackListener((undoAvailable, redoAvailable) -> {
       Log.d("ALAN", String.format("Undo/Redo available: %s, %s", undoAvailable ? "Y" : "N", redoAvailable ? "Y" : "N"));
       if (menu == null) return;

image-editor/lib/src/main/java/org/signal/imageeditor/core/HiddenEditText.java

@@ -17,6 +17,10 @@ import androidx.annotation.Nullable;
 import org.signal.imageeditor.core.model.EditorElement;
 import org.signal.imageeditor.core.renderers.MultiLineTextRenderer;
 
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+
 /**
  * Invisible {@link android.widget.EditText} that is used during in-image text editing.
  */
@@ -37,6 +41,8 @@ public final class HiddenEditText extends androidx.appcompat.widget.AppCompatEdi
   @Nullable
   private OnEditOrSelectionChange onEditOrSelectionChange;
 
+  private List<TextFilter> textFilters = new LinkedList<>();
+
   public HiddenEditText(Context context) {
     super(context);
     setAlpha(0);
@@ -54,7 +60,11 @@ public final class HiddenEditText extends androidx.appcompat.widget.AppCompatEdi
   protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
     super.onTextChanged(text, start, lengthBefore, lengthAfter);
     if (currentTextEntity != null) {
-      currentTextEntity.setText(text.toString());
+      String filtered = text.toString();
+      for (TextFilter filter : textFilters) {
+        filtered = filter.filter(filtered);
+      }
+      currentTextEntity.setText(filtered);
       postEditOrSelectionChange();
     }
   }
@@ -79,6 +89,18 @@ public final class HiddenEditText extends androidx.appcompat.widget.AppCompatEdi
     }
   }
 
+  public void addTextFilter(@NonNull TextFilter filter) {
+    textFilters.add(filter);
+  }
+
+  public void addTextFilters(@NonNull Collection<TextFilter> filters) {
+    textFilters.addAll(filters);
+  }
+
+  public void removeTextFilter(@NonNull TextFilter filter) {
+    textFilters.remove(filter);
+  }
+
   private void endEdit() {
     if (onEndEdit != null) {
       onEndEdit.run();
@@ -173,4 +195,11 @@ public final class HiddenEditText extends androidx.appcompat.widget.AppCompatEdi
   public interface OnEditOrSelectionChange {
     void onChange(@NonNull EditorElement editorElement, @NonNull MultiLineTextRenderer textRenderer);
   }
+
+  public interface TextFilter {
+    /**
+     * Given an input string, return a filtered version.
+     */
+    String filter(@NonNull String text);
+  }
 }

image-editor/lib/src/main/java/org/signal/imageeditor/core/ImageEditorView.java

@@ -24,6 +24,9 @@ import org.signal.imageeditor.core.renderers.BezierDrawingRenderer;
 import org.signal.imageeditor.core.renderers.MultiLineTextRenderer;
 import org.signal.imageeditor.core.renderers.TrashRenderer;
 
+import java.util.LinkedList;
+import java.util.List;
+
 /**
  * ImageEditorView
  * <p>
@@ -71,6 +74,8 @@ public final class ImageEditorView extends FrameLayout {
   @Nullable
   private DragListener dragListener;
 
+  private final List<HiddenEditText.TextFilter> textFilters = new LinkedList<>();
+
   private final Matrix viewMatrix      = new Matrix();
   private final RectF  viewPort        = Bounds.newFullBounds();
   private final RectF  visibleViewPort = Bounds.newFullBounds();
@@ -116,6 +121,8 @@ public final class ImageEditorView extends FrameLayout {
     editText.clearFocus();
     editText.setOnEndEdit(this::doneTextEditing);
     editText.setOnEditOrSelectionChange(this::zoomToFitText);
+    editText.addTextFilters(textFilters);
+
     return editText;
   }
 
@@ -150,6 +157,16 @@ public final class ImageEditorView extends FrameLayout {
     this.typefaceProvider = typefaceProvider;
   }
 
+  public void addTextInputFilter(@NonNull HiddenEditText.TextFilter inputFilter) {
+    textFilters.add(inputFilter);
+    editText = createAHiddenTextEntryField();
+  }
+
+  public void removeTextInputFilter(@NonNull HiddenEditText.TextFilter inputFilter) {
+    textFilters.remove(inputFilter);
+    editText = createAHiddenTextEntryField();
+  }
+
   @Override
   protected void onDraw(Canvas canvas) {
     if (rendererContext == null || rendererContext.canvas != canvas || rendererContext.typefaceProvider != typefaceProvider) {