Merge pull request #1057 from edx/usman/lms-1114-pdf-arrows

Disables the previous/next arrows on pdf books on the first/last pages

common/static/js/pdfviewer.js

@@ -200,6 +200,18 @@ PDFJS.disableWorker = true;
             document.getElementById('numPages').textContent = 'of ' + pdfDocument.numPages;
             $("#pageNumber").max = pdfDocument.numPages;
             $("#pageNumber").val(pageNum);
+
+            // Enable/disable the previous/next buttons
+            if (pageNum <= 1) {
+              $("#previous").addClass("is-disabled");
+            } else {
+              $("#previous").removeClass("is-disabled");
+            }
+            if (pageNum >= pdfDocument.numPages) {
+              $("#next").addClass("is-disabled");
+            } else {
+              $("#next").removeClass("is-disabled");
+            }
         }
 
         // Go to previous page

lms/static/sass/course/_textbook.scss

@@ -163,10 +163,13 @@ div.book-wrapper {
 
             &:hover {
               opacity: 1.0;
-              filter: alpha(opacity=100);
+            }
+
+            &.is-disabled {
+              display:none;
             }
           }
-
+          
           &.last {
             left: 0;