Use native invite.png QR

sites/+components/qr_modals.php

@@ -4,7 +4,26 @@
 		return "$QR_CODES/$room_id.png";
 	}
 
-	 /*
+	/*
+	 * Takes join URL and derives the invite.png path from it
+	 */
+	function room_qr_code_native($join_url) {
+		// Ex.: https://open.getsession.org/session?public_key=[...]
+		// Goal: https://open.getsession.org/r/session/invite.png
+		// Note: No @legacy support (Ex.: https://reccacon.com/view/Ukraine/invite.png)
+		// TODO: How does this behave with unreliable connections to Chinese servers?
+		$exploded = explode("/", explode("?", $join_url)[0]); // everything before "?"
+		$png_url =
+			$exploded[0] . "//" .         // https://
+			$exploded[2] . "/r/" .        // open.getsession.org/r/
+			$exploded[3] . "/invite.png"; // session/invite.png
+
+//		fwrite(STDERR, "PNG URL: " . $png_url . PHP_EOL);
+		return $png_url;
+	}
+
+	/*
+	 * @Deprecated
 	 * Use Google API to generate QR codes and encode them as base64
 	 */
 	function base64_qr_code($room_id, $join_url, $size = "512x512") {
@@ -37,10 +56,20 @@
 		<span class="qr-code-modal-close" onclick='hideQRModal("<?=$id?>")'>
 			&times;
 		</span>
+		<!--
 		<img 
 			src="data:image/png;base64,<?=base64_qr_code($id, $room->join_link)?>"
 			alt="Community join link encoded as QR code"
 			class="qr-code"
+			loading="lazy"
+		>
+		-->
+		<img
+			src="<?=room_qr_code_native($room->join_link)?>"
+			alt="Community join link encoded as QR code"
+			class="qr-code"
+			loading="lazy"
+			referrerpolicy="no-referrer"
 		>
 	</div>
 </div>