add memory optimization and UTF-8 safety

Author: GREENRAT-K405

src/graph-builder/graph-core/5-load-save.js

@@ -43,8 +43,11 @@ class GraphLoadSave extends GraphUndoRedo {
         }
         if (format === 'PNG-EMBEDDED') {
             const b64Uri = this.cy.png({ full: true });
-            const b64Data = b64Uri.split(',')[1];
-            const buffer = new Uint8Array(window.atob(b64Data).split('').map((c) => c.charCodeAt(0)));
+            const binaryString = window.atob(b64Uri.split(',')[1]);
+            const buffer = new Uint8Array(binaryString.length);
+            for (let i = 0; i < binaryString.length; i += 1) {
+                buffer[i] = binaryString.charCodeAt(i);
+            }
             const chunks = extractChunks(buffer);
             chunks.splice(-1, 0, textChunk.encode('graphml', this.getGraphML()));
             const newBuffer = new Uint8Array(encodeChunks(chunks));
@@ -54,8 +57,11 @@ class GraphLoadSave extends GraphUndoRedo {
         }
         if (format === 'JPG-EMBEDDED') {
             const b64Uri = this.cy.jpg({ full: true });
-            const b64Data = b64Uri.split(',')[1];
-            const buffer = new Uint8Array(window.atob(b64Data).split('').map((c) => c.charCodeAt(0)));
+            const binaryString = window.atob(b64Uri.split(',')[1]);
+            const buffer = new Uint8Array(binaryString.length);
+            for (let i = 0; i < binaryString.length; i += 1) {
+                buffer[i] = binaryString.charCodeAt(i);
+            }
             const graphMLStr = this.getGraphML();
             const graphMLBytes = new TextEncoder().encode(graphMLStr);
 

src/toolbarActions/toolbarFunctions.js

@@ -223,18 +223,30 @@ const readFile = async (state, setState, file, fileHandle) => {
                 try {
                     const buffer = new Uint8Array(x.target.result);
                     let pos = 2; // skip SOI
-                    let graphMLData = '';
+                    const comSegments = [];
                     while (pos < buffer.length) {
                         if (buffer[pos] !== 0xFF) break;
                         const marker = buffer[pos + 1];
                         if (marker === 0xDA) break; // SOS - Start of Scan
                         const len = (buffer[pos + 2] * 256) + buffer[pos + 3];
                         if (marker === 0xFE) { // COM Comment segment
-                            graphMLData += new TextDecoder().decode(buffer.slice(pos + 4, pos + 2 + len));
+                            comSegments.push(buffer.slice(pos + 4, pos + 2 + len));
                         }
                         pos += 2 + len;
                     }
 
+                    let graphMLData = '';
+                    if (comSegments.length > 0) {
+                        const totalLength = comSegments.reduce((sum, seg) => sum + seg.length, 0);
+                        const allBytes = new Uint8Array(totalLength);
+                        let offset = 0;
+                        for (let i = 0; i < comSegments.length; i += 1) {
+                            allBytes.set(comSegments[i], offset);
+                            offset += comSegments[i].length;
+                        }
+                        graphMLData = new TextDecoder().decode(allBytes);
+                    }
+
                     if (graphMLData) {
                         parser(graphMLData).then(({ authorName }) => {
                             setState({