Adjust emoji advance and size.

Runtime/ui/txt/emoji.cs

 
         public const int rowCount = 36;
         public const int colCount = 37;
+        public static float advanceFactor = 1.3f;
+        public static float sizeFactor = 1.2f;
-            return Rect.fromLTWH(0, descent/2-fontSize, fontSize, fontSize);
+            return Rect.fromLTWH((advanceFactor - sizeFactor) / 2 * fontSize,
+                descent - fontSize * sizeFactor,
+                fontSize * sizeFactor,
+                fontSize * sizeFactor);
         }
 
         public static Rect getUVRect(int code) {

Runtime/ui/txt/layout.cs

             char startingChar = text[0];
             float totalWidth = 0;
             if (char.IsHighSurrogate(startingChar) || EmojiUtils.isSingleCharEmoji(startingChar)) {
-                float advance = style.fontSize + style.letterSpacing;
+                float advance = style.fontSize * EmojiUtils.advanceFactor + style.letterSpacing;
                 for (int i = 0; i < text.Length; i++) {
                     char ch = text[i];
                     if (char.IsHighSurrogate(ch) || EmojiUtils.isSingleCharNonEmptyEmoji(ch)) {
             char startingChar = text[start];
             float currentAdvance = offset;
             if (char.IsHighSurrogate(startingChar) || EmojiUtils.isSingleCharEmoji(startingChar)) {
-                float advance = style.fontSize + style.letterSpacing;
+                float advance = style.fontSize * EmojiUtils.advanceFactor + style.letterSpacing;
                 for (int i = 0; i < count; i++) {
                     char ch = text[start + i];
                     if (char.IsHighSurrogate(ch) || EmojiUtils.isSingleCharNonEmptyEmoji(ch)) {
             char startingChar = text[start];
             float totalWidths = 0;
             if (char.IsHighSurrogate(startingChar) || EmojiUtils.isSingleCharEmoji(startingChar)) {
-                float advance = style.fontSize + style.letterSpacing;
+                float advance = style.fontSize * EmojiUtils.advanceFactor + style.letterSpacing;
                 for (int i = 0; i < count; i++) {
                     char ch = text[start + i];
                     if (char.IsHighSurrogate(ch) || EmojiUtils.isSingleCharNonEmptyEmoji(ch)) {
                     x += letterSpaceHalfLeft;
                     advances[i] = letterSpaceHalfLeft;
 
-
+                    float advance = style.fontSize * EmojiUtils.advanceFactor;
-                    var maxX = style.fontSize + x;
-                    var minY = metrics.descent/2 - style.fontSize;
-                    var maxY = metrics.descent/2;
+                    var maxX = advance + x;
+                    var minY = -style.fontSize * EmojiUtils.sizeFactor;
+                    var maxY = metrics.descent;
-                    float advance = style.fontSize;
                     x += advance;
 
                     advances[i] += advance;