Print Preview: Detecting plugin existence before generating the preview.

chrome/browser/resources/print_preview.js

Index: chrome/browser/resources/print_preview.js
diff --git a/chrome/browser/resources/print_preview.js b/chrome/browser/resources/print_preview.js
index 5c2bb573d08f23304ed4f05c38cf0c3fcf627f2b..e877410d4cb2de9f6f6da701cf06f65eb5b672ff 100644
--- a/chrome/browser/resources/print_preview.js
+++ b/chrome/browser/resources/print_preview.js
@@ -4,10 +4,6 @@
 
 var localStrings = new LocalStrings();
 
-// Whether or not the PDF plugin supports all the capabilities needed for
-// print preview.
-var hasCompatiblePDFPlugin = true;
-
 // The total page count of the previewed document regardless of which pages the
 // user has selected.
 var totalPageCount = -1;
@@ -48,10 +44,18 @@ const MANAGE_PRINTERS = 'Manage Printers';
  * the printer list.
  */
 function onLoad() {
+  $('system-dialog-link').addEventListener('click', showSystemDialog);
+  $('cancel-button').addEventListener('click', handleCancelButtonClick);
+  $('dummy-viewer').classList.add('hidden');
+
+  if(!checkCompatiblePluginExists()) {

[Lei Zhang, 2011/05/11 22:19:51]

nit: space after if

[dpapad, 2011/05/11 23:31:03]

Done.

+    displayErrorMessage(localStrings.getString('noPlugin'));
+    return;
+  }
+

[vandebo (ex-Chrome), 2011/05/11 22:13:54]

Should we remove the dummy-viewer is some way so that we aren't running two
instances of the plugin?

[dpapad, 2011/05/11 23:31:03]

The plugin is removed from the page on line 49. If there is a better way to
remove it sure, but I dont have something in mind.

   $('printer-list').disabled = true;
   $('print-button').disabled = true;
   $('print-button').addEventListener('click', printFile);
-  $('cancel-button').addEventListener('click', handleCancelButtonClick);
   $('all-pages').addEventListener('click', onPageSelectionMayHaveChanged);
   $('copies').addEventListener('input', copiesFieldChanged);
   $('print-pages').addEventListener('click', handleIndividualPagesCheckbox);
@@ -68,7 +72,6 @@ function onLoad() {
   $('bw').addEventListener('click', function() { setColor(false); });
   $('printer-list').addEventListener(
       'change', updateControlsWithSelectedPrinterCapabilities);
-  $('system-dialog-link').addEventListener('click', showSystemDialog);
   $('increment').addEventListener('click',
                                   function() { onCopiesButtonsClicked(1); });
   $('decrement').addEventListener('click',
@@ -323,7 +326,6 @@ function printFile() {
 function requestPrintPreview() {
   isPreviewStillLoading = true;
   setControlsDisabled(true);
-  $('dancing-dots').classList.remove('hidden');
   $('dancing-dots').classList.remove('invisible');
   chrome.send('getPreview', [getSettingsJSON()]);
 }
@@ -374,9 +376,6 @@ function addDestinationListOption(optionText, optionValue, is_default) {
  * @param {boolean} color is true if the PDF plugin should display in color.
  */
 function setColor(color) {
-  if (!hasCompatiblePDFPlugin) {
-    return;
-  }
   var pdfViewer = $('pdf-viewer');
   if (!pdfViewer) {
     return;
@@ -390,6 +389,7 @@ function setColor(color) {
  */
 function displayErrorMessage(errorMessage) {
   isPreviewStillLoading = false;
+  $('dancing-dots').classList.remove('invisible');
   $('dancing-dots-text').classList.add('hidden');
   $('error-text').innerHTML = errorMessage;
   $('error-text').classList.remove('hidden');
@@ -462,10 +462,6 @@ function updatePrintPreview(pageCount, jobTitle, mimeType) {
  * Create the PDF plugin or reload the existing one.
  */
 function createPDFPlugin() {
-  if (!hasCompatiblePDFPlugin) {
-    return;
-  }
-
   // Enable the print button.
   if (!$('printer-list').disabled) {
     $('print-button').disabled = false;
@@ -491,13 +487,6 @@ function createPDFPlugin() {
   pdfPlugin.setAttribute('src', 'chrome://print/print.pdf');
   var mainView = $('mainview');
   mainView.appendChild(pdfPlugin);
-
-  // Check to see if the PDF plugin is our PDF plugin. (or compatible)
-  if (!pdfPlugin.onload) {
-    hasCompatiblePDFPlugin = false;
-    displayErrorMessage(localStrings.getString('noPlugin'));
-    return;
-  }
   pdfPlugin.onload('onPDFLoad()');
 
   // Older version of the PDF plugin may not have this method.
@@ -510,6 +499,14 @@ function createPDFPlugin() {
 }
 
 /**
+ * Returns true if a compatible pdf plugin exists, false if it doesn't.
+ */
+function checkCompatiblePluginExists() {
+  var dummyPlugin = $('dummy-viewer')
+  return !!dummyPlugin.onload;
+}
+
+/**
  * Updates the state of print button depending on the user selection.
  * The button is enabled only when the following conditions are true.
  * 1) The selected page ranges are valid.