SimpleChatTCRV:Vision: DataUrl helpers

Move all dataUrl handling into helper functions.

So that its manipulation is done in a controlled manner, as well as
in future, changes to the semantic can be easily carried out by
updating the helper functions suitably and inturn updating the caller
as needed.

For now avoid push and pop and work with 0th index directly, given
that currently the logic is setup for handling only a single image
with the ai model. This keeps things simple. It can be changed if
required in future easily.

tools/server/public_simplechat/simplechat.js

@@ -972,9 +972,8 @@ class MultiChatUI {
             console.log(`DBUG:InFileX:${f0?.name}`)
             let fR = new FileReader()
             fR.onload = () => {
-                if ((fR.result) && (typeof(fR.result) == 'string')) {
-                    this.me.dataURLs.push(fR.result)
-                    this.elInFileX.elImg.src = fR.result
+                if (fR.result) {
+                    this.dataurl_plus_add(fR.result)
                     console.log(`INFO:InFileX:Loaded file ${f0.name}`)
                 }
             }
@@ -1034,9 +1033,31 @@ class MultiChatUI {
         }
     }
 
+    /**
+     * Add a dataUrl, as well as show Image.
+     * @param {string | ArrayBuffer | null} dataUrl
+     */
+    dataurl_plus_add(dataUrl) {
+        if (typeof(dataUrl) == 'string') {
+            //this.me.dataURLs.push(dataUrl)
+            this.me.dataURLs[0] = dataUrl
+            this.elInFileX.elImg.src = dataUrl
+        }
+    }
+
+    /**
+     * Get the stored dataUrl
+     */
+    dataurl_get() {
+        //this.me.dataURLs.pop()
+        return /** @type{string} */(this.me.dataURLs[0])
+    }
+
+    /**
+     * Clear dataUrls, as well as clear Image.
+     */
     dataurl_plus_clear() {
         this.elInFileX.elImg.src = "";
-        //this.me.dataURLs.pop()
         this.me.dataURLs.length = 0;
     }
 
@@ -1368,7 +1389,7 @@ class MultiChatUI {
             try {
                 let image = undefined
                 if (this.me.dataURLs.length > 0) {
-                    image = /** @type{string} */(this.me.dataURLs[0])
+                    image = this.dataurl_get()
                 }
                 chat.add(new ChatMessageEx(new NSChatMessage(Roles.User, content, undefined, undefined, undefined, undefined, image)))
             } catch (err) {