From adba0073e398593a912368aa0ec41715f821abf7 Mon Sep 17 00:00:00 2001
From: Anton Lavrevov <lavrton@gmail.com>
Date: Mon, 23 Dec 2024 12:29:30 -0500
Subject: [PATCH] fixes in emoji rendering

---
 src/shapes/Text.ts     | 50 +++++++++++++++++++++++++++---------------
 test/unit/Text-test.ts | 29 ++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 18 deletions(-)

diff --git a/src/shapes/Text.ts b/src/shapes/Text.ts
index 284590ae..a54b1d6a 100644
--- a/src/shapes/Text.ts
+++ b/src/shapes/Text.ts
@@ -18,10 +18,15 @@ export function stringToArray(string: string): string[] {
   return [...string].reduce((acc, char, index, array) => {
     // Handle emoji with skin tone modifiers and ZWJ sequences
     if (/\p{Emoji}/u.test(char)) {
-      if (acc.length > 0 && /\p{Emoji}/u.test(acc[acc.length - 1])) {
-        // Combine with previous emoji if it's part of a sequence
-        acc[acc.length - 1] += char;
+      // Check if next character is a modifier or ZWJ sequence
+      const nextChar = array[index + 1];
+      if (nextChar && /\p{Emoji_Modifier}|\u200D/u.test(nextChar)) {
+        // If we have a modifier, combine with current emoji
+        acc.push(char + nextChar);
+        // Skip the next character since we've used it
+        array[index + 1] = '';
       } else {
+        // No modifier - treat as separate emoji
         acc.push(char);
       }
     }
@@ -36,7 +41,8 @@ export function stringToArray(string: string): string[] {
       acc[acc.length - 1] += char;
     }
     // Handle other characters
-    else {
+    else if (char) {
+      // Only push if not an empty string (skipped modifier)
       acc.push(char);
     }
     return acc;
@@ -520,13 +526,16 @@ export class Text extends Shape<TextConfig> {
            * that would fit in the specified width
            */
           let low = 0,
-            high = line.length,
+            high = stringToArray(line).length, // Convert to array for proper emoji handling
             match = '',
             matchWidth = 0;
           while (low < high) {
             const mid = (low + high) >>> 1,
-              substr = line.slice(0, mid + 1),
+              // Convert array indices to string
+              lineArray = stringToArray(line),
+              substr = lineArray.slice(0, mid + 1).join(''),
               substrWidth = this._getTextWidth(substr) + additionalWidth;
+
             if (substrWidth <= maxWidth) {
               low = mid + 1;
               match = substr;
@@ -544,20 +553,24 @@ export class Text extends Shape<TextConfig> {
             // a fitting substring was found
             if (wrapAtWord) {
               // try to find a space or dash where wrapping could be done
-              var wrapIndex;
-              const nextChar = line[match.length];
+              const lineArray = stringToArray(line);
+              const matchArray = stringToArray(match);
+              const nextChar = lineArray[matchArray.length];
               const nextIsSpaceOrDash = nextChar === SPACE || nextChar === DASH;
+
+              let wrapIndex;
               if (nextIsSpaceOrDash && matchWidth <= maxWidth) {
-                wrapIndex = match.length;
+                wrapIndex = matchArray.length;
               } else {
-                wrapIndex =
-                  Math.max(match.lastIndexOf(SPACE), match.lastIndexOf(DASH)) +
-                  1;
+                // Find last space or dash in the array
+                const lastSpaceIndex = matchArray.lastIndexOf(SPACE);
+                const lastDashIndex = matchArray.lastIndexOf(DASH);
+                wrapIndex = Math.max(lastSpaceIndex, lastDashIndex) + 1;
               }
+
               if (wrapIndex > 0) {
-                // re-cut the substring found at the space/dash position
                 low = wrapIndex;
-                match = match.slice(0, low);
+                match = lineArray.slice(0, low).join('');
                 matchWidth = this._getTextWidth(match);
               }
             }
@@ -578,13 +591,14 @@ export class Text extends Shape<TextConfig> {
                */
               break;
             }
-            line = line.slice(low);
-            line = line.trimLeft();
+
+            // Convert remaining text using array operations
+            const lineArray = stringToArray(line);
+            line = lineArray.slice(low).join('').trimLeft();
+
             if (line.length > 0) {
-              // Check if the remaining text would fit on one line
               lineWidth = this._getTextWidth(line);
               if (lineWidth <= maxWidth) {
-                // if it does, add the line and break out of the loop
                 this._addTextLine(line);
                 currentHeightPx += lineHeightPx;
                 textWidth = Math.max(textWidth, lineWidth);
diff --git a/test/unit/Text-test.ts b/test/unit/Text-test.ts
index 206fe0f2..b2d7ea52 100644
--- a/test/unit/Text-test.ts
+++ b/test/unit/Text-test.ts
@@ -161,6 +161,35 @@ describe('Text', function () {
     context.fillStyle = 'darkgrey';
     context.fillText('😬👧🏿', 10, 10 + 25);
 
+    compareLayerAndCanvas(layer, canvas, 254, 100);
+  });
+
+  it('check emoji rendering', function () {
+    var stage = addStage();
+    var layer = new Konva.Layer();
+
+    var text = new Konva.Text({
+      text: '😁😁😁',
+      x: 10,
+      y: 10,
+      fontSize: 20,
+      draggable: true,
+      width: 65,
+      fill: 'black',
+      scaleY: 0.9999999999999973,
+    });
+
+    layer.add(text);
+    stage.add(layer);
+
+    var canvas = createCanvas();
+    var context = canvas.getContext('2d');
+    context.textBaseline = 'middle';
+    context.font = 'normal normal 20px Arial';
+    context.fillStyle = 'black';
+    context.fillText('😁😁', 10, 10 + 10);
+    context.fillText('😁', 10, 10 + 30);
+
     compareLayerAndCanvas(layer, canvas, 254);
   });