Add QR code to file viewer

res/include/script/file_viewer/QRCodeWindow.js

@@ -0,0 +1,35 @@
+function QRCodeWindow(viewer) {
+	this.viewer = viewer
+	this.visible = false
+	this.modal = new Modal(
+		document.getElementById("file_viewer"),
+		() => { this.toggle() },
+		"QR code", "500px", "auto",
+	)
+
+	this.img = document.createElement("img")
+	this.img.style.display = "block"
+	this.img.style.width = "100%"
+	this.modal.setBody(this.img)
+
+	this.btnQRCode = document.getElementById("btn_qr_code")
+	this.btnQRCode.addEventListener("click", () => { this.toggle() })
+
+	this.setFile()
+}
+
+QRCodeWindow.prototype.toggle = function () {
+	if (this.visible) {
+		this.modal.close()
+		this.btnQRCode.classList.remove("button_highlight")
+		this.visible = false
+	} else {
+		this.modal.open()
+		this.btnQRCode.classList.add("button_highlight")
+		this.visible = true
+	}
+}
+
+QRCodeWindow.prototype.setFile = function () {
+	this.img.src = "/api/misc/qr?text=" + encodeURIComponent(window.location.href)
+}