[GENERIC viewer] Re-factor the fileInput initialization

*This is yet another installment in a never-ending series of patches that attempt to simplify and improve old code.*

The `fileInput`-element is used to support the "Open file"-button in the `GENERIC` viewer, however this is very old code.
Rather than creating the element dynamically in JavaScript, we can simply define it conditionally in the HTML code thanks to the pre-processor. Furthermore, the `fileInput`-element currently has a number of unnecessary CSS rules, since the element is *purposely* never made visibly.

Note that with these changes, the `fileInput`-element will now *always* have `display: none;` set. This shouldn't matter, since we can still trigger the `click`-event of the element just fine (via JavaScript) and this patch has been successfully tested in both Mozilla Firefox and Google Chrome.

web/app.js

@@ -2142,7 +2142,7 @@ function reportPageStatsPDFBug({ pageNumber }) {
 }
 
 function webViewerInitialized() {
-  const appConfig = PDFViewerApplication.appConfig;
+  const { appConfig, eventBus } = PDFViewerApplication;
   let file;
   if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
     const queryString = document.location.search.substring(1);
@@ -2156,13 +2156,7 @@ function webViewerInitialized() {
   }
 
   if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
-    const fileInput = document.createElement("input");
+    const fileInput = appConfig.openFileInput;
-    fileInput.id = appConfig.openFileInputName;
-    fileInput.className = "fileInput";
-    fileInput.setAttribute("type", "file");
-    fileInput.oncontextmenu = noContextMenuHandler;
-    document.body.appendChild(fileInput);
-
     if (
       !window.File ||
       !window.FileReader ||
@@ -2176,11 +2170,11 @@ function webViewerInitialized() {
     }
 
     fileInput.addEventListener("change", function (evt) {
-      const files = evt.target.files;
+      const { files } = evt.target;
       if (!files || files.length === 0) {
         return;
       }
-      PDFViewerApplication.eventBus.dispatch("fileinputchange", {
+      eventBus.dispatch("fileinputchange", {
         source: this,
         fileInput: evt.target,
       });
@@ -2195,11 +2189,11 @@ function webViewerInitialized() {
     appConfig.mainContainer.addEventListener("drop", function (evt) {
       evt.preventDefault();
 
-      const files = evt.dataTransfer.files;
+      const { files } = evt.dataTransfer;
       if (!files || files.length === 0) {
         return;
       }
-      PDFViewerApplication.eventBus.dispatch("fileinputchange", {
+      eventBus.dispatch("fileinputchange", {
         source: this,
         fileInput: evt.dataTransfer,
       });
@@ -2234,7 +2228,7 @@ function webViewerInitialized() {
     "transitionend",
     function (evt) {
       if (evt.target === /* mainContainer */ this) {
-        PDFViewerApplication.eventBus.dispatch("resize", { source: this });
+        eventBus.dispatch("resize", { source: this });
       }
     },
     true
@@ -2460,8 +2454,8 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
   };
 
   webViewerOpenFile = function (evt) {
-    const openFileInputName = PDFViewerApplication.appConfig.openFileInputName;
+    const fileInput = PDFViewerApplication.appConfig.openFileInput;
-    document.getElementById(openFileInputName).click();
+    fileInput.click();
   };
 }
 

web/viewer.css

@@ -1364,16 +1364,6 @@ dialog :link {
   clear: both;
 }
 
-.fileInput {
-  background: rgba(255, 255, 255, 1);
-  color: rgba(0, 0, 0, 1);
-  margin-top: 5px;
-  visibility: hidden;
-  position: fixed;
-  right: 0;
-  top: 0;
-}
-
 #PDFBug {
   background: none repeat scroll 0 0 rgba(255, 255, 255, 1);
   border: 1px solid rgba(102, 102, 102, 1);
@@ -1537,10 +1527,6 @@ dialog :link {
     display: block;
   }
 
-  .fileInput {
-    display: none;
-  }
-
   /* Rules for browsers that support PDF.js printing */
   body[data-pdfjsprinting] #outerContainer {
     display: none;

web/viewer.html

@@ -448,5 +448,9 @@ See https://github.com/adobe-type-tools/cmap-resources
 
     </div> <!-- outerContainer -->
     <div id="printContainer"></div>
+
+<!--#if GENERIC -->
+    <input type="file" id="fileInput" class="hidden">
+<!--#endif-->
   </body>
 </html>

web/viewer.js

@@ -189,7 +189,10 @@ function getViewerConfiguration() {
     },
     errorWrapper,
     printContainer: document.getElementById("printContainer"),
-    openFileInputName: "fileInput",
+    openFileInput:
+      typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")
+        ? document.getElementById("fileInput")
+        : null,
     debuggerScriptPath: "./debugger.js",
   };
 }