Print Preview: Fixing behavior of event listeners.

chrome/browser/resources/print_preview/print_preview.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // require: cr/ui/print_preview_cloud.js
 
 var localStrings = new LocalStrings();
 
 // If useCloudPrint is true we attempt to connect to cloud print
 // and populate the list of printers with cloud print printers.
@@ skipping 18 matching lines @@
 
 // The name of the default or last used printer.
 var defaultOrLastUsedPrinterName = '';
 
 // True when a pending print preview request exists.
 var hasPendingPreviewRequest = false;
 
 // The ID of the last preview request.
 var lastPreviewRequestID = -1;
 
+// The ID of the initial preview request.
+var initialPreviewRequestID = -1;
+
 // True when a pending print file request exists.
 var hasPendingPrintDocumentRequest = false;
 
 // True when preview tab is hidden.
 var isTabHidden = false;
 
 // Object holding all the pages related settings.
 var pageSettings;
 
 // Object holding all the copies related settings.
@@ skipping 24 matching lines @@
 
 // The maximum number of cloud printers to allow in the dropdown.
 const maxCloudPrinters = 10;
 
 /**
  * Window onload handler, sets up the page and starts print preview by getting
  * the printer list.
  */
 function onLoad() {
   cr.enablePlatformSpecificCSSRules();
+  initialPreviewRequestID = getRandomIntegerWithinRange(0, 32000);

[Lei Zhang, 2011/08/06 00:52:57]

Is this so if we reload the page, we have a unique starting point, whereas 0 can
be confused with the preview tab's request from before the reload?

[dpapad, 2011/08/06 01:21:20]

Exactly. This was happening when reloading the page repeatedly (several requests
with the same id=0 in flight). Also I stop the range to 32000, because I want to
make sure that it fits in a c integer (I could increase it a little bit more
though).

+  lastPreviewRequestID = initialPreviewRequestID;
 
   if (!checkCompatiblePluginExists()) {
     disableInputElementsInSidebar();
     displayErrorMessageWithButton(localStrings.getString('noPlugin'),
                                   localStrings.getString('launchNativeDialog'),
                                   launchNativePrintDialog);
     $('mainview').parentElement.removeChild($('dummy-viewer'));
     return;
   }
 
   $('system-dialog-link').addEventListener('click', onSystemDialogLinkClicked);
   $('mainview').parentElement.removeChild($('dummy-viewer'));
 
   $('printer-list').disabled = true;
 
   printHeader = print_preview.PrintHeader.getInstance();
   pageSettings = print_preview.PageSettings.getInstance();
   copiesSettings = print_preview.CopiesSettings.getInstance();
   layoutSettings = print_preview.LayoutSettings.getInstance();
   colorSettings = print_preview.ColorSettings.getInstance();
   printHeader.addEventListeners();
   pageSettings.addEventListeners();
   copiesSettings.addEventListeners();
   layoutSettings.addEventListeners();
   colorSettings.addEventListeners();
+  $('printer-list').onchange = updateControlsWithSelectedPrinterCapabilities;
 
   showLoadingAnimation();
   chrome.send('getDefaultPrinter');
 }
 
 /**
- * Adds event listeners to the settings controls.
- */
-function addEventListeners() {
-  // Controls that require preview rendering.
-  $('printer-list').onchange = updateControlsWithSelectedPrinterCapabilities;
-}
-
-/**
- * Removes event listeners from the settings controls.
- */
-function removeEventListeners() {
-  if (pageSettings)
-    clearTimeout(pageSettings.timerId_);
-
-  // Controls that require preview rendering
-  $('printer-list').onchange = null;
-}
-
-/**
  * Disables the input elements in the sidebar.
  */
 function disableInputElementsInSidebar() {
   var els = $('sidebar').querySelectorAll('input, button, select');
   for (var i = 0; i < els.length; i++)
     els[i].disabled = true;
 }
 
 /**
  * Disables the controls in the sidebar, shows the throbber and instructs the
@@ skipping 161 matching lines @@
   var settings =
       {'deviceName': deviceName,
        'pageRange': pageSettings.selectedPageRanges,
        'printAll': pageSettings.allPagesRadioButton.checked,
        'duplex': copiesSettings.duplexMode,
        'copies': copiesSettings.numberOfCopies,
        'collate': copiesSettings.isCollated(),
        'landscape': layoutSettings.isLandscape(),
        'color': colorSettings.isColor(),
        'printToPDF': printToPDF,
+       'isFirstRequst' : false,
        'requestID': 0};
 
   var printerList = $('printer-list');
   var selectedPrinter = printerList.selectedIndex;
   if (cloudprint.isCloudPrint(printerList.options[selectedPrinter])) {
     settings['cloudPrintID'] =
         printerList.options[selectedPrinter].value;
   }
   return settings;
 }
 
 /**
  * @return {number} The next unused preview request id.
  */
 function generatePreviewRequestID() {
   return ++lastPreviewRequestID;
 }
 
 /**
  * @return {boolean} True iff a preview has been requested.
  */
 function hasRequestedPreview() {
-  return lastPreviewRequestID > -1;
+  return lastPreviewRequestID != initialPreviewRequestID;
 }
 
 /**
+ * @return {boolean} True iff this is the |lastPreviewRequestID| corresponds
+ *     to the initial preview request.
+ */
+function isFirstPreviewRequest() {
+  return lastPreviewRequestID == initialPreviewRequestID + 1;
+}
+
+/**
  * Checks if |previewResponseId| matches |lastPreviewRequestId|. Used to ignore
  * obsolete preview data responses.
  * @param {number} previewResponseId The id to check.
  * @return {boolean} True if previewResponseId reffers to the expected response.
  */
 function isExpectedPreviewResponse(previewResponseId) {
   return lastPreviewRequestID == previewResponseId;
 }
 
 /**
@@ skipping 24 matching lines @@
      } else {
        isTabHidden = true;
        chrome.send('hidePreview');
      }
     return;
   }
 
   if (printToPDF) {
     sendPrintDocumentRequest();
   } else {
-    removeEventListeners();
     window.setTimeout(function() { sendPrintDocumentRequest(); }, 1000);
   }
 }
 
 /**
  * Asks the browser to print the pending preview PDF that just finished
  * loading.
  */
 function requestToPrintPendingDocument() {
   hasPendingPrintDocumentRequest = false;
@@ skipping 23 matching lines @@
                                   cloudprint.getData(printer)]);
   chrome.send('print', [JSON.stringify(getSettings()),
                         cloudprint.getPrintTicketJSON(printer)]);
 }
 
 /**
  * Asks the browser to generate a preview PDF based on current print settings.
  */
 function requestPrintPreview() {
   hasPendingPreviewRequest = true;
-  removeEventListeners();
   printSettings.save();
   if (!isTabHidden)
     showLoadingAnimation();
 
   var settings = getSettings();
   settings.requestID = generatePreviewRequestID();
+  settings.isFirstRequest = isFirstPreviewRequest();
   chrome.send('getPreview', [JSON.stringify(settings)]);
 }
 
 /**
  * Called from PrintPreviewUI::OnFileSelectionCancelled to notify the print
  * preview tab regarding the file selection cancel event.
  */
 function fileSelectionCancelled() {
   // TODO(thestig) re-enable controls here.
 }
@@ skipping 279 matching lines @@
 /**
  * Display an error message in the center of the preview area.
  * @param {string} errorMessage The error message to be displayed.
  */
 function displayErrorMessage(errorMessage) {
   $('print-button').disabled = true;
   $('overlay-layer').classList.remove('invisible');
   $('dancing-dots-text').classList.add('hidden');
   $('error-text').innerHTML = errorMessage;
   $('error-text').classList.remove('hidden');
-  removeEventListeners();
   var pdfViewer = $('pdf-viewer');
   if (pdfViewer)
     $('mainview').removeChild(pdfViewer);
 
   if (isTabHidden)
     cancelPendingPrintRequest();
 }
 
 /**
  * Display an error message in the center of the preview area followed by a
@@ skipping 22 matching lines @@
 function printPreviewFailed() {
   displayErrorMessage(localStrings.getString('previewFailed'));
 }
 
 /**
  * Called when the PDF plugin loads its document.
  */
 function onPDFLoad() {
   if (previewModifiable) {
     setPluginPreviewPageCount();
-    cr.dispatchSimpleEvent(document, 'updateSummary');
   }
   $('pdf-viewer').fitToHeight();
   cr.dispatchSimpleEvent(document, 'PDFLoaded');
   hideLoadingAnimation();
 }
 
 function setPluginPreviewPageCount() {
   $('pdf-viewer').printPreviewPageCount(
       pageSettings.previouslySelectedPages.length);
 }
 
 /**
  * Update the page count and check the page range.
  * Called from PrintPreviewUI::OnDidGetPreviewPageCount().
  * @param {number} pageCount The number of pages.
  * @param {boolean} isModifiable Indicates whether the previewed document can be
  *     modified.
+ * @param {number} previewResponseId The preview request id that resulted in
+ *     this response.
  */
-function onDidGetPreviewPageCount(pageCount, isModifiable) {
+function onDidGetPreviewPageCount(pageCount, isModifiable, previewResponseId) {
+  console.log("onDidGetPreviewPageCount " + previewResponseId);
+  if (!isExpectedPreviewResponse(previewResponseId))
+    return;
   pageSettings.updateState(pageCount);
   previewModifiable = isModifiable;
+  cr.dispatchSimpleEvent(document, 'updateSummary');
 }
 
 /**
  * Called when no pipelining previewed pages.
+ * @param {string} previewUid Preview unique identifier.
+ * @param {number} previewResponseId The preview request id that resulted in
+ *     this response.
  */
 function reloadPreviewPages(previewUid, previewResponseId) {
+  console.log("reloadPreviewPages " + previewResponseId);
   if (!isExpectedPreviewResponse(previewResponseId))
     return;
   hasPendingPreviewRequest = false;
 
   if (checkIfSettingsChangedAndRegeneratePreview())
     return;
-  cr.dispatchSimpleEvent(document, 'updateSummary');
   cr.dispatchSimpleEvent(document, 'updatePrintButton');
-  addEventListeners();
   hideLoadingAnimation();
   var pageSet = pageSettings.previouslySelectedPages;
   for (var i = 0; i < pageSet.length; i++)
     $('pdf-viewer').loadPreviewPage(getPageSrcURL(previewUid, pageSet[i]-1), i);
   // TODO(dpapad): handle pending print file requests.
 }
 
 /**
  * Notification that a print preview page has been rendered.
  * Check if the settings have changed and request a regeneration if needed.
  * Called from PrintPreviewUI::OnDidPreviewPage().
  * @param {number} pageNumber The page number, 0-based.
+ * @param {string} previewUid Preview unique identifier.
+ * @param {number} previewResponseId The preview request id that resulted in
+ *     this response.
  */
-function onDidPreviewPage(pageNumber, previewUid) {
+function onDidPreviewPage(pageNumber, previewUid, previewResponseId) {
+  console.log("onDidPreviewPage " + previewResponseId + " " + pageNumber);
+  if (!isExpectedPreviewResponse(previewResponseId))
+    return;
+
   // Refactor
   if (!previewModifiable)
     return;
 
   var pageIndex = pageSettings.previouslySelectedPages.indexOf(pageNumber + 1);
 
   if (checkIfSettingsChangedAndRegeneratePreview())
     return;
   if (pageIndex == 0)
     createPDFPlugin(previewUid);
 
   $('pdf-viewer').loadPreviewPage(
       getPageSrcURL(previewUid, pageNumber), pageIndex);
 }
 
 /**
  * Update the print preview when new preview data is available.
  * Create the PDF plugin as needed.
  * Called from PrintPreviewUI::PreviewDataIsAvailable().
  * @param {string} jobTitle The print job title.
  * @param {boolean} modifiable If the preview is modifiable.
  * @param {string} previewUid Preview unique identifier.
  * @param {number} previewResponseId The preview request id that resulted in
  *     this response.
  */
 function updatePrintPreview(jobTitle,
                             previewUid,
                             previewResponseId) {
+  console.log("updatePrintPreview" + previewResponseId);
   if (!isExpectedPreviewResponse(previewResponseId))
     return;
   hasPendingPreviewRequest = false;
 
   if (checkIfSettingsChangedAndRegeneratePreview())
     return;
 
   document.title = localStrings.getStringF('printPreviewTitleFormat', jobTitle);
 
   if (!previewModifiable) {
     // If the preview is not modifiable the plugin has not been created yet.
     createPDFPlugin(previewUid);
   }
 
-  cr.dispatchSimpleEvent(document, 'updateSummary');
   cr.dispatchSimpleEvent(document, 'updatePrintButton');
-  addEventListeners();
 
   if (hasPendingPrintDocumentRequest)
     requestToPrintPendingDocument();
 }
 
 /**
  * Check if any print settings changed and regenerate the preview if needed.
  * @return {boolean} true if a new preview is required.
  */
 function checkIfSettingsChangedAndRegeneratePreview() {
@@ skipping 76 matching lines @@
 }
 
 /**
  * Takes a snapshot of the print settings.
  */
 PrintSettings.prototype.save = function() {
   this.deviceName = getSelectedPrinterName();
   this.isLandscape = layoutSettings.isLandscape();
 }