Make the TU passes

vector/src/main/java/im/vector/riotx/core/utils/Emoji.kt

@@ -113,3 +113,39 @@ fun containsOnlyEmojis(str: String?): Boolean {
 
     return res
 }
+
+/**
+ * Same as split, but considering emojis
+ */
+fun CharSequence.splitEmoji(): List<CharSequence> {
+    val result = mutableListOf<CharSequence>()
+
+    var index = 0
+
+    while (index < length) {
+        val firstChar = get(index)
+
+        if (firstChar.toInt() == 0x200e) {
+            // Left to right mark. What should I do with it?
+        } else if (firstChar.toInt() in 0xD800..0xDBFF && index + 1 < length) {
+            // We have the start of a surrogate pair
+            val secondChar = get(index + 1)
+
+            if (secondChar.toInt() in 0xDC00..0xDFFF) {
+                // We have an emoji
+                result.add("$firstChar$secondChar")
+                index++
+            } else {
+                // Not sure what we have here...
+                result.add("$firstChar")
+            }
+        } else {
+            // Regular char
+            result.add("$firstChar")
+        }
+
+        index++
+    }
+
+    return result
+}

vector/src/main/java/im/vector/riotx/features/home/room/detail/composer/rainbow/RainbowGenerator.kt

@@ -16,6 +16,7 @@
 
 package im.vector.riotx.features.home.room.detail.composer.rainbow
 
+import im.vector.riotx.core.utils.splitEmoji
 import javax.inject.Inject
 import kotlin.math.abs
 import kotlin.math.roundToInt
@@ -30,9 +31,10 @@ class RainbowGenerator @Inject constructor() {
         val frequency = 360f / text.length
 
         return text
+                .splitEmoji()
                 .mapIndexed { idx, letter ->
                     // Do better than React-Sdk: Avoid adding font color for spaces
-                    if (letter == ' ') {
+                    if (letter == " ") {
                         "$letter"
                     } else {
                         val dashColor = hueToRGB(idx * frequency, 1.0f, 0.5f).toDashColor()

vector/src/test/java/im/vector/riotx/features/home/room/detail/composer/rainbow/RainbowGeneratorTest.kt

@@ -64,7 +64,7 @@ class RainbowGeneratorTest {
 
     @Test
     fun testEmoji1() {
-        assertEquals("""<font color="#ff0000">\uD83E\uDD1E</font>""", rainbowGenerator.generate("\uD83E\uDD1E")) // 🤞
+        assertEquals("""<font color="#ff0000">🤞</font>""", rainbowGenerator.generate("\uD83E\uDD1E")) // 🤞
     }
 
     @Test
@@ -75,24 +75,20 @@ class RainbowGeneratorTest {
     @Test
     fun testEmojiMix() {
         val expected = """
-            <font color="#ff0000">T</font>
-            <font color="#ff5500">h</font>
-            <font color="#ffaa00">i</font>
-            <font color="#ffff00">s</font>
+            <font color="#ff0000">H</font>
+            <font color="#ff6600">e</font>
+            <font color="#ffcc00">l</font>
+            <font color="#ccff00">l</font>
+            <font color="#66ff00">o</font>
              
-            <font color="#55ff00">i</font>
-            <font color="#00ff00">s</font>
+            <font color="#00ff66">🤞</font>
              
-            <font color="#00ffaa">a</font>
-             
-            <font color="#00aaff">r</font>
-            <font color="#0055ff">a</font>
-            <font color="#0000ff">i</font>
-            <font color="#5500ff">n</font>
-            <font color="#aa00ff">b</font>
-            <font color="#ff00ff">o</font>
-            <font color="#ff00aa">w</font>
-            <font color="#ff0055">!</font>
+            <font color="#00ccff">w</font>
+            <font color="#0066ff">o</font>
+            <font color="#0000ff">r</font>
+            <font color="#6600ff">l</font>
+            <font color="#cc00ff">d</font>
+            <font color="#ff00cc">!</font>
         """
                 .trimIndent()
                 .replace("\n", "")