Print preview page selection should not require a rerendering of draft pages.

chrome/renderer/print_web_view_helper.cc

Index: chrome/renderer/print_web_view_helper.cc
diff --git a/chrome/renderer/print_web_view_helper.cc b/chrome/renderer/print_web_view_helper.cc
index 1735d90b7e661e1a46a8eebc778efd4688d310ab..541ae857d167acc6e71e3cf06354f0a658d70a99 100644
--- a/chrome/renderer/print_web_view_helper.cc
+++ b/chrome/renderer/print_web_view_helper.cc
@@ -177,6 +177,7 @@ PrintWebViewHelper::PrintWebViewHelper(RenderView* render_view)
       RenderViewObserverTracker<PrintWebViewHelper>(render_view),
       print_web_view_(NULL),
       is_preview_(switches::IsPrintPreviewEnabled()),
+      is_complete_metafile_already_sent_(false),
       user_cancelled_scripted_print_count_(0),
       notify_browser_of_print_failure_(true) {
 }
@@ -339,9 +340,18 @@ void PrintWebViewHelper::OnPrintPreview(const DictionaryValue& settings) {
   }
   // Always clear |old_print_pages_params_| before rendering the pages.
   old_print_pages_params_.reset();
+  is_complete_metafile_already_sent_ = false;
 
   // PDF printer device supports alpha blending.
   print_pages_params_->params.supports_alpha_blend = true;
+
+  bool generate_draft_pages;
+  if (!settings.GetBoolean(printing::kSettingGenerateDraftData,
+                           &generate_draft_pages)) {
+    NOTREACHED();
+  }
+  print_preview_context_.set_generate_draft_pages(generate_draft_pages);

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

If you like, you could make set_generate_draft_pages take settings, and do the
work of extracting the value in the setter.

[kmadhusu, 2011/08/05 22:55:22]

I prefer the existing code.

+
   if (!CreatePreviewDocument())
     DidFinishPrinting(FAIL_PREVIEW);
 }
@@ -354,37 +364,38 @@ bool PrintWebViewHelper::CreatePreviewDocument() {
   int page_count = print_preview_context_.total_page_count();
   bool is_modifiable = print_preview_context_.IsModifiable();
   int document_cookie = print_pages_params_->params.document_cookie;
-  Send(new PrintHostMsg_DidGetPreviewPageCount(routing_id(), document_cookie,
-                                               page_count, is_modifiable));
+  Send(new PrintHostMsg_DidGetPreviewPageCount(
+    routing_id(),

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

nit: 4 space indent.

[kmadhusu, 2011/08/05 22:55:22]

Done.

+    document_cookie,
+    page_count,
+    is_modifiable,
+    print_preview_context_.generate_draft_pages()));
   PreviewPageRendered(printing::INVALID_PAGE_INDEX, NULL);
   return true;
 }
 
-void PrintWebViewHelper::OnContinuePreview(int requested_preview_page_index) {
+void PrintWebViewHelper::OnContinuePreview() {
   // Spurious message. We already finished/cancelled/aborted the print preview.
   if (!print_preview_context_.IsBusy())
     return;
-  int page_number;
-#if defined(USE_SKIA)
-  if (requested_preview_page_index >= printing::FIRST_PAGE_INDEX) {
-    page_number = requested_preview_page_index;
-  } else
-#endif
-  {
-    page_number = print_preview_context_.GetNextPageNumber();
-  }
-
+  int page_number = print_preview_context_.GetNextPageNumber();
   if (page_number >= printing::FIRST_PAGE_INDEX) {
     // Continue generating the print preview.
     RenderPreviewPage(page_number);
-    return;
+    if (!print_preview_context_.IsLastPageOfCompleteMetafile())

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

This is still a bit confusing/interwoven...  I suggest adding method to pp
context to tell you if you're done (like GetNextPageNumber, but const) and
removing the early return in this block and then:
if (done) {PreviewPageRenderered()}
if (LastPageOfCompleteMF()) {Finalize()}
if (page_num is invalid) {Finished(), DidFinishPrinting(OK)}

[kmadhusu, 2011/08/05 22:55:22]

Done.

+      return;
   }
 
-  // Finished generating preview. Finalize the document.
-  if (FinalizePreviewDocument()) {
+  if (is_complete_metafile_already_sent_ &&
+      page_number == printing::INVALID_PAGE_INDEX) {
+    print_preview_context_.PreviewPagesRendered();
     print_preview_context_.Finished();
     DidFinishPrinting(OK);
-  } else {
+    return;
+  }
+
+  // Finished generating preview. Finalize the document.
+  if (!FinalizePreviewDocument()) {
     DidFinishPrinting(FAIL_PREVIEW);
   }
 }
@@ -395,6 +406,7 @@ void PrintWebViewHelper::OnAbortPreview() {
 }
 
 bool PrintWebViewHelper::FinalizePreviewDocument() {
+  DCHECK(!is_complete_metafile_already_sent_);
   print_preview_context_.FinalizePreviewDocument();
 
   // Get the size of the resulting metafile.
@@ -417,6 +429,8 @@ bool PrintWebViewHelper::FinalizePreviewDocument() {
                                    &(preview_params.metafile_data_handle))) {
     return false;
   }
+  is_complete_metafile_already_sent_ = true;
+
   Send(new PrintHostMsg_PagesReadyForPreview(routing_id(), preview_params));
   return true;
 }
@@ -937,8 +951,9 @@ void PrintWebViewHelper::PreviewPageRendered(int page_number,
 PrintWebViewHelper::PrintPreviewContext::PrintPreviewContext()
     : frame_(NULL),
       total_page_count_(0),
-      actual_page_count_(0),
-      current_page_number_(0),
+      render_page_list_index_(-1),
+      generate_draft_pages_(true),
+      complete_metafile_page_count_(0),
       state_(UNINITIALIZED) {
 }
 
@@ -992,23 +1007,25 @@ bool PrintWebViewHelper::PrintPreviewContext::CreatePreviewDocument(
   if (total_page_count_ == 0)
     return false;
 
-  current_page_number_ = 0;
-  if (pages.empty()) {
-    actual_page_count_ = total_page_count_;
-    rendered_pages_ = std::vector<PreviewPageInfo>(total_page_count_,
-                                                   std::make_pair(false, -1));
+  int selected_page_count = pages.size();
+  render_page_list_index_ = -1;
+  complete_metafile_page_count_ = pages.empty() ? total_page_count_ :
+                                                  selected_page_count;
+  if (selected_page_count == 0) {
+    // When |pages| is empty, we always generate all draft pages.

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

I was hoping for a bit more here...  "And render_page_list_ will be populated by
the draft_page below." or something like that.

[kmadhusu, 2011/08/05 22:55:22]

Done.

+    DCHECK(generate_draft_pages_);
   } else {
-    actual_page_count_ = pages.size();
-    rendered_pages_ = std::vector<PreviewPageInfo>(total_page_count_,
-                                                   std::make_pair(true, -1));
-    for (int i = 0; i < actual_page_count_; ++i) {
-      int page_number = pages[i];
-      if (page_number < printing::FIRST_PAGE_INDEX ||
-          page_number >= total_page_count_) {
-        return false;
+    render_page_list_ = pages;

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

If you like, this can be done unconditionally - either before or after the if.

[kmadhusu, 2011/08/05 22:55:22]

Done.

+  }
+
+  if (generate_draft_pages_) {
+    int index = 0;

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

nit: pages_index ?

[kmadhusu, 2011/08/05 22:55:22]

Done.

+    for (int i = 0; i < total_page_count_; i++) {
+      if (index < selected_page_count && i == pages[index]) {
+        index++;
+        continue;
       }
-      rendered_pages_[page_number].first = false;
-      rendered_pages_[page_number].second = i;
+      render_page_list_.push_back(i);
     }
   }
 
@@ -1025,16 +1042,21 @@ void PrintWebViewHelper::PrintPreviewContext::RenderedPreviewPage(
   UMA_HISTOGRAM_TIMES("PrintPreview.RenderPDFPageTime", page_time);
 }
 
-void PrintWebViewHelper::PrintPreviewContext::FinalizePreviewDocument() {
+void PrintWebViewHelper::PrintPreviewContext::PreviewPagesRendered() {
   DCHECK_EQ(RENDERING, state_);
   state_ = DONE;
+  prep_frame_view_->FinishPrinting();
+}
 
-  base::TimeTicks begin_time = base::TimeTicks::Now();
+void PrintWebViewHelper::PrintPreviewContext::FinalizePreviewDocument() {
+  DCHECK_EQ(RENDERING, state_);
+  if ((size_t)(render_page_list_index_ + 1) == render_page_list_.size())
+    PreviewPagesRendered();

[vandebo (ex-Chrome), 2011/08/04 21:45:02]

I think the reordering suggestion I made in OnContinuePreview above may make
this unnecessary ?

[kmadhusu, 2011/08/05 22:55:22]

Removed.

 
-  prep_frame_view_->FinishPrinting();
+  base::TimeTicks begin_time = base::TimeTicks::Now();
   metafile_->FinishDocument();
 
-  if (actual_page_count_ <= 0) {
+  if (complete_metafile_page_count_ <= 0) {
     NOTREACHED();
     return;
   }
@@ -1046,7 +1068,7 @@ void PrintWebViewHelper::PrintPreviewContext::FinalizePreviewDocument() {
   UMA_HISTOGRAM_MEDIUM_TIMES("PrintPreview.RenderAndGeneratePDFTime",
                              total_time);
   UMA_HISTOGRAM_MEDIUM_TIMES("PrintPreview.RenderAndGeneratePDFTimeAvgPerPage",
-                             total_time / actual_page_count_);
+                             total_time / render_page_list_.size());
 }
 
 void PrintWebViewHelper::PrintPreviewContext::Finished() {
@@ -1063,15 +1085,10 @@ void PrintWebViewHelper::PrintPreviewContext::Abort() {
 
 int PrintWebViewHelper::PrintPreviewContext::GetNextPageNumber() {
   DCHECK_EQ(RENDERING, state_);
-  for (int i = 0; i < total_page_count_; i++) {
-    if (!rendered_pages_[current_page_number_].first)
-      break;
-    current_page_number_ = (current_page_number_ + 1) % total_page_count_;
-  }
-  if (rendered_pages_[current_page_number_].first)
+  if ((size_t)(render_page_list_index_ + 1) >= render_page_list_.size())
     return printing::INVALID_PAGE_INDEX;
-  rendered_pages_[current_page_number_].first = true;
-  return current_page_number_;
+  render_page_list_index_++;
+  return render_page_list_[render_page_list_index_];
 }
 
 bool PrintWebViewHelper::PrintPreviewContext::IsReadyToRender() const {
@@ -1092,6 +1109,16 @@ bool PrintWebViewHelper::PrintPreviewContext::IsModifiable() const {
   return mime != "application/pdf";
 }
 
+bool PrintWebViewHelper::PrintPreviewContext::IsLastPageOfCompleteMetafile()
+    const {
+  return render_page_list_index_ == complete_metafile_page_count_ - 1;
+}
+
+void PrintWebViewHelper::PrintPreviewContext::set_generate_draft_pages(
+    bool generate_draft_pages) {
+  generate_draft_pages_ = generate_draft_pages;
+}
+
 WebKit::WebFrame* PrintWebViewHelper::PrintPreviewContext::frame() const {
   return frame_;
 }
@@ -1104,6 +1131,10 @@ int PrintWebViewHelper::PrintPreviewContext::total_page_count() const {
   return total_page_count_;
 }
 
+bool PrintWebViewHelper::PrintPreviewContext::generate_draft_pages() {
+  return generate_draft_pages_;
+}
+
 printing::Metafile* PrintWebViewHelper::PrintPreviewContext::metafile() const {
   return metafile_.get();
 }
@@ -1121,5 +1152,5 @@ PrintWebViewHelper::PrintPreviewContext::GetPrintCanvasSize() const {
 void PrintWebViewHelper::PrintPreviewContext::ClearContext() {
   prep_frame_view_.reset();
   metafile_.reset();
-  rendered_pages_.clear();
+  render_page_list_.clear();
 }