Print Preview: Make print preview tab modal.

chrome/renderer/print_web_view_helper.cc

Index: chrome/renderer/print_web_view_helper.cc
===================================================================
--- chrome/renderer/print_web_view_helper.cc	(revision 105826)
+++ chrome/renderer/print_web_view_helper.cc	(working copy)
@@ -8,6 +8,7 @@
 
 #include "base/command_line.h"
 #include "base/logging.h"
+#include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
@@ -467,8 +468,21 @@
   IncrementScriptedPrintCount();
 
   if (is_preview_) {
+    // Ignore window.print() if this view is already doing window.print().
+    if (print_preview_context_.in_nested_message_loop())
+      return;
+
     print_preview_context_.InitWithFrame(frame);
     RequestPrintPreview();
+
+    WebView::willEnterModalLoop();
+    MessageLoop* message_loop = MessageLoop::current();
+    print_preview_context_.set_in_nested_message_loop(true);
+    bool old_state = message_loop->NestableTasksAllowed();
+    message_loop->SetNestableTasksAllowed(true);
+    message_loop->Run();
+    message_loop->SetNestableTasksAllowed(old_state);
+    WebView::didExitModalLoop();
   } else {
     Print(frame, WebNode());
   }
@@ -489,6 +503,8 @@
                         ResetScriptedPrintCount)
     IPC_MESSAGE_HANDLER(PrintMsg_PreviewPrintingRequestCancelled,
                         DisplayPrintJobError)
+    IPC_MESSAGE_HANDLER(PrintMsg_PrintPreviewDone,
+                        OnPrintPreviewDone)
     IPC_MESSAGE_UNHANDLED(handled = false)
     IPC_END_MESSAGE_MAP()
   return handled;
@@ -1259,6 +1275,13 @@
       l10n_util::GetStringUTF16(IDS_PRINT_SPOOL_FAILED_ERROR_TEXT));
 }
 
+void PrintWebViewHelper::OnPrintPreviewDone() {
+  if (print_preview_context_.in_nested_message_loop()) {
+    print_preview_context_.set_in_nested_message_loop(false);
+    MessageLoop::current()->QuitNow();
+  }
+}
+
 void PrintWebViewHelper::RequestPrintPreview() {
   old_print_pages_params_.reset();
   Send(new PrintHostMsg_RequestPrintPreview(routing_id()));
@@ -1317,6 +1340,7 @@
 
 PrintWebViewHelper::PrintPreviewContext::PrintPreviewContext()
     : frame_(NULL),
+      in_nested_message_loop_(false),
       total_page_count_(0),
       current_page_index_(0),
       generate_draft_pages_(true),
@@ -1490,6 +1514,12 @@
   error_ = error;
 }
 
+void PrintWebViewHelper::PrintPreviewContext::set_in_nested_message_loop(
+    bool nested) {
+  CHECK(!nested || !in_nested_message_loop_);
+  in_nested_message_loop_ = nested;
+}
+
 WebKit::WebFrame* PrintWebViewHelper::PrintPreviewContext::frame() const {
   return frame_;
 }
@@ -1498,6 +1528,10 @@
   return node_;
 }
 
+bool PrintWebViewHelper::PrintPreviewContext::in_nested_message_loop() const {
+  return in_nested_message_loop_;

[darin (slow to review), 2011/10/17 22:16:33]

can you explain why you need this member variable?  do you receive spurious
calls to OnPrintPreviewDone?

[Lei Zhang, 2011/10/17 22:26:05]

Yes, it is possible to receive spurious calls to OnPrintPreviewDone.

Also, a webpage that contains JS code like window.onresize = function(event) {
window.print(); } will hit the check at line 472.

+}
+
 int PrintWebViewHelper::PrintPreviewContext::total_page_count() const {
   DCHECK(IsReadyToRender());
   return total_page_count_;