Show toast to user when trying to draw without a document open

src/js/drawtools.js

@@ -44,7 +44,11 @@ function makeStampImage(callback) {
 }
 
 function activateTextTool() {
-    var text = prompt("");
+    if (!canUseDrawTools()) {
+        showToast("Please open a document first.");
+        return;
+    }
+    var text = prompt("Enter a line of text to add to the document:");
     if (text == "") {
         return;
     }
@@ -69,6 +73,10 @@ function activateTextTool() {
 }
 
 function activateStampDrawTool() {
+    if (!canUseDrawTools()) {
+        showToast("Please open a document first.");
+        return;
+    }
     makeStampImage(function (image) {
         activeDrawImage = image;
         enableGuideBox(image);
@@ -76,6 +84,10 @@ function activateStampDrawTool() {
 }
 
 function activateNotarySignatureTool() {
+    if (!canUseDrawTools()) {
+        showToast("Please open a document first.");
+        return;
+    }
     if (!inStorage("notary_signature")) {
         showAlert("Please set a notary signature in the settings.");
         return;
@@ -91,6 +103,10 @@ function activateNotarySignatureTool() {
 }
 
 function activateNotaryCertificateTool() {
+    if (!canUseDrawTools()) {
+        showToast("Please open a document first.");
+        return;
+    }
     initCertificateBuilder();
 
     certificateBuilderCallback = function () {
@@ -108,6 +124,10 @@ function activateNotaryCertificateTool() {
 }
 
 function activateClientSignaturePad() {
+    if (!canUseDrawTools()) {
+        showToast("Please open a document first.");
+        return;
+    }
     initSignaturePad();
     signaturePadCallback = function () {
         if (clientSignatureSvg != "" && signaturePad.isEmpty()) {
@@ -228,6 +248,14 @@ function getMousePos(canvas, evt) {
     }
 }
 
+/**
+ * Returns true if drawing tools should be available (i.e. there's a document to draw on)
+ * @returns {Boolean}
+ */
+function canUseDrawTools() {
+    return $("#page-canvas-container .page-canvas").length > 0;
+}
+
 // Hide it at start
 // doesn't work in CSS because of reasons
 disableGuideBox();

src/js/pdf.js

@@ -386,6 +386,10 @@ function getNewCanvas(pagenumber) {
 }
 
 function addPage() {
+    if ($("#page-canvas-container .page-canvas").length == 0) {
+        showToast("Please open a document first.");
+        return;
+    }
     pageNumber++;
     var canvas = getNewCanvas(pageNumber);
     var prevPageCanvas = $("#page-canvas-container .page-canvas#pdf-canvas-page-" + (pageNumber - 1))[0];