When an emoji is used as the 'initial' for an avatar, use the whole emoji (#4277)

* When an emoji is used as the 'initial' for an avatar, use the whole emoji

Use `BreakIterator.getCharacterInstance()` for a simpler solution.

libraries/designsystem/build.gradle.kts

@@ -33,6 +33,7 @@ android {
         implementation(libs.vanniktech.blurhash)
         implementation(projects.features.enterprise.api)
         implementation(projects.libraries.architecture)
+        implementation(projects.libraries.core)
         implementation(projects.libraries.preferences.api)
         implementation(projects.libraries.testtags)
         implementation(projects.libraries.uiStrings)

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/AvatarData.kt

@@ -8,6 +8,8 @@
 package io.element.android.libraries.designsystem.components.avatar
 
 import androidx.compose.runtime.Immutable
+import io.element.android.libraries.core.data.tryOrNull
+import java.text.BreakIterator
 
 @Immutable
 data class AvatarData(
@@ -27,24 +29,36 @@ data class AvatarData(
                     startIndex++
                 }
 
-                var length = 1
+                var next = dn[startIndex]
-                var first = dn[startIndex]
 
                 // LEFT-TO-RIGHT MARK
-                if (dn.length >= 2 && 0x200e == first.code) {
+                if (dn.length >= 2 && 0x200e == next.code) {
                     startIndex++
-                    first = dn[startIndex]
+                    next = dn[startIndex]
                 }
 
-                // check if it’s the start of a surrogate pair
+                while (next.isWhitespace()) {
-                if (first.code in 0xD800..0xDBFF && dn.length > startIndex + 1) {
+                    if (dn.length > startIndex + 1) {
-                    val second = dn[startIndex + 1]
+                        startIndex++
-                    if (second.code in 0xDC00..0xDFFF) {
+                        next = dn[startIndex]
-                        length++
+                    } else {
+                        break
                     }
                 }
 
-                dn.substring(startIndex, startIndex + length)
+                val fullCharacterIterator = BreakIterator.getCharacterInstance()
+                fullCharacterIterator.setText(dn)
+                val glyphBoundary = tryOrNull { fullCharacterIterator.following(startIndex) }
+                    ?.takeIf { it in startIndex..dn.length }
+
+                when {
+                    // Use the found boundary
+                    glyphBoundary != null -> dn.substring(startIndex, glyphBoundary)
+                    // If no boundary was found, default to the next char if possible
+                    startIndex + 1 < dn.length -> dn.substring(startIndex, startIndex + 1)
+                    // Return a fallback character otherwise
+                    else -> "#"
+                }
             }
             .uppercase()
     }

libraries/designsystem/src/test/kotlin/io/element/android/libraries/designsystem/components/avatar/AvatarDataTest.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.designsystem.components.avatar
+
+import com.google.common.truth.Truth.assertThat
+import org.junit.Test
+
+class AvatarDataTest {
+    @Test
+    fun `initial with text should get the first char, uppercased`() {
+        val data = AvatarData("id", "test", null, AvatarSize.InviteSender)
+        assertThat(data.initial).isEqualTo("T")
+    }
+
+    @Test
+    fun `initial with leading whitespace should get the first non-whitespace char, uppercased`() {
+        val data = AvatarData("id", " test", null, AvatarSize.InviteSender)
+        assertThat(data.initial).isEqualTo("T")
+    }
+
+    @Test
+    fun `initial with long emoji should get the full emoji`() {
+        val data = AvatarData("id", "\uD83C\uDFF3\uFE0F\u200D\uD83C\uDF08 Test", null, AvatarSize.InviteSender)
+        assertThat(data.initial).isEqualTo("\uD83C\uDFF3\uFE0F\u200D\uD83C\uDF08")
+    }
+
+    @Test
+    fun `initial with short emoji should get the emoji`() {
+        val data = AvatarData("id", "✂ Test", null, AvatarSize.InviteSender)
+        assertThat(data.initial).isEqualTo("✂")
+    }
+
+    @Test
+    fun `initial with a single letter should take that letter`() {
+        val data = AvatarData("id", "T", null, AvatarSize.InviteSender)
+        assertThat(data.initial).isEqualTo("T")
+    }
+}