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

chrome/renderer/print_web_view_helper.cc

 // 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.
 
 #include "chrome/renderer/print_web_view_helper.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 479 matching lines @@
     if (WebFrame* web_frame = web_view_->mainFrame())
       web_frame->setScrollOffset(prev_scroll_offset_);
   }
 }
 
 PrintWebViewHelper::PrintWebViewHelper(RenderView* render_view)
     : RenderViewObserver(render_view),
       RenderViewObserverTracker<PrintWebViewHelper>(render_view),
       print_web_view_(NULL),
       is_preview_(switches::IsPrintPreviewEnabled()),
+      is_print_ready_metafile_sent_(false),
       user_cancelled_scripted_print_count_(0),
       notify_browser_of_print_failure_(true) {
 }
 
 PrintWebViewHelper::~PrintWebViewHelper() {}
 
 // Prints |frame| which called window.print().
 void PrintWebViewHelper::PrintPage(WebKit::WebFrame* frame) {
   DCHECK(frame);
 
@@ skipping 139 matching lines @@
     preview_params.reuse_existing_data = true;
     preview_params.data_size = 0;
     preview_params.document_cookie =
         print_pages_params_->params.document_cookie;
     preview_params.expected_pages_count =
         print_preview_context_.total_page_count();
     preview_params.modifiable = print_preview_context_.IsModifiable();
     preview_params.preview_request_id =
         print_pages_params_->params.preview_request_id;
 
-    Send(new PrintHostMsg_PagesReadyForPreview(routing_id(), preview_params));
+    Send(new PrintHostMsg_MetafileReadyForPrinting(routing_id(),
+                                                   preview_params));
     return;
   }
   // Always clear |old_print_pages_params_| before rendering the pages.
   old_print_pages_params_.reset();
+  is_print_ready_metafile_sent_ = false;
 
   // PDF printer device supports alpha blending.
   print_pages_params_->params.supports_alpha_blend = true;
+
+  bool generate_draft_pages = false;
+  if (!settings.GetBoolean(printing::kSettingGenerateDraftData,
+                           &generate_draft_pages)) {
+    NOTREACHED();
+  }
+  print_preview_context_.set_generate_draft_pages(generate_draft_pages);
+
   if (CreatePreviewDocument()) {
     DidFinishPrinting(OK);
   } else {
     if (notify_browser_of_print_failure_)
       LOG(ERROR) << "CreatePreviewDocument failed";
     DidFinishPrinting(FAIL_PREVIEW);
   }
 }
 
 bool PrintWebViewHelper::CreatePreviewDocument() {
   PrintMsg_Print_Params print_params = print_pages_params_->params;
   const std::vector<int>& pages = print_pages_params_->pages;
   if (!print_preview_context_.CreatePreviewDocument(&print_params, pages))
     return false;
   PrintHostMsg_DidGetPreviewPageCount_Params params;
   params.page_count = print_preview_context_.total_page_count();
   params.is_modifiable = print_preview_context_.IsModifiable();
   params.document_cookie = print_pages_params_->params.document_cookie;
   params.preview_request_id = print_pages_params_->params.preview_request_id;
+  params.clear_preview_data = print_preview_context_.generate_draft_pages();
   Send(new PrintHostMsg_DidGetPreviewPageCount(routing_id(), params));
   if (CheckForCancel())
     return false;
 
   int page_number;
   while ((page_number = print_preview_context_.GetNextPageNumber()) >= 0) {
     if (!RenderPreviewPage(page_number))
       return false;
     if (CheckForCancel())
       return false;
-  };
-
-  // Finished generating preview. Finalize the document.
-  if (!FinalizePreviewDocument())
-    return false;
+    if (print_preview_context_.IsLastPageOfPrintReadyMetafile()) {
+      // Finished generating preview. Finalize the document.
+      if (!FinalizePrintReadyDocument())
+        return false;
+    }
+  }
+  print_preview_context_.AllPagesRendered();
   print_preview_context_.Finished();
   return true;
 }
 
-bool PrintWebViewHelper::FinalizePreviewDocument() {
-  print_preview_context_.FinalizePreviewDocument();
+bool PrintWebViewHelper::FinalizePrintReadyDocument() {
+  DCHECK(!is_print_ready_metafile_sent_);
+  print_preview_context_.FinalizePrintReadyDocument();
 
   // Get the size of the resulting metafile.
   printing::PreviewMetafile* metafile = print_preview_context_.metafile();
   uint32 buf_size = metafile->GetDataSize();
   DCHECK_GT(buf_size, 0u);
 
   PrintHostMsg_DidPreviewDocument_Params preview_params;
   preview_params.reuse_existing_data = false;
   preview_params.data_size = buf_size;
   preview_params.document_cookie = print_pages_params_->params.document_cookie;
   preview_params.expected_pages_count =
       print_preview_context_.total_page_count();
   preview_params.modifiable = print_preview_context_.IsModifiable();
   preview_params.preview_request_id =
       print_pages_params_->params.preview_request_id;
 
   // Ask the browser to create the shared memory for us.
   if (!CopyMetafileDataToSharedMem(metafile,
                                    &(preview_params.metafile_data_handle))) {
     LOG(ERROR) << "CopyMetafileDataToSharedMem failed";
     return false;
   }
-  Send(new PrintHostMsg_PagesReadyForPreview(routing_id(), preview_params));
+  is_print_ready_metafile_sent_ = true;
+
+  Send(new PrintHostMsg_MetafileReadyForPrinting(routing_id(), preview_params));
   return true;
 }
 
 void PrintWebViewHelper::OnPrintingDone(bool success) {
   notify_browser_of_print_failure_ = false;
   if (!success)
     LOG(ERROR) << "Failure in OnPrintingDone";
   DidFinishPrinting(success ? OK : FAIL_PRINT);
 }
 
@@ skipping 507 matching lines @@
   if (cancel)
     notify_browser_of_print_failure_ = false;
   return cancel;
 }
 
 bool PrintWebViewHelper::PreviewPageRendered(int page_number,
                                              printing::Metafile* metafile) {
   DCHECK_GE(page_number, printing::FIRST_PAGE_INDEX);
 
   // For non-modifiable files, |metafile| should be NULL, so do not bother
-  // sending a message.
-  if (!print_preview_context_.IsModifiable()) {
+  // sending a message. If we don't generate draft metafiles, |metafile| is
+  // NULL.
+  if (!print_preview_context_.IsModifiable() ||
+      !print_preview_context_.generate_draft_pages()) {
     DCHECK(!metafile);
     return true;
   }
 
   if (!metafile) {
     NOTREACHED();
     return false;
   }
 
   PrintHostMsg_DidPreviewPage_Params preview_page_params;
@@ skipping 10 matching lines @@
   preview_page_params.preview_request_id =
       print_pages_params_->params.preview_request_id;
 
   Send(new PrintHostMsg_DidPreviewPage(routing_id(), preview_page_params));
   return true;
 }
 
 PrintWebViewHelper::PrintPreviewContext::PrintPreviewContext()
     : frame_(NULL),
       total_page_count_(0),
-      actual_page_count_(0),
       current_page_index_(0),
+      generate_draft_pages_(true),
+      print_ready_metafile_page_count_(0),
       state_(UNINITIALIZED) {
 }
 
 PrintWebViewHelper::PrintPreviewContext::~PrintPreviewContext() {
 }
 
 void PrintWebViewHelper::PrintPreviewContext::InitWithFrame(
     WebKit::WebFrame* web_frame) {
   DCHECK(web_frame);
   state_ = INITIALIZED;
@@ skipping 33 matching lines @@
                                                          node()));
   UpdatePrintableSizeInPrintParameters(frame_, node_.get(),
                                        prep_frame_view_.get(), print_params);
 
   total_page_count_ = prep_frame_view_->GetExpectedPageCount();
   if (total_page_count_ == 0) {
     LOG(ERROR) << "CreatePreviewDocument got 0 page count";
     return false;
   }
 
+  int selected_page_count = pages.size();
   current_page_index_ = 0;
-  if (pages.empty()) {
-    actual_page_count_ = total_page_count_;
-    for (int i = 0; i < actual_page_count_; ++i)
+  print_ready_metafile_page_count_ = selected_page_count;
+  pages_to_render_ = pages;
+
+  if (selected_page_count == 0) {
+    print_ready_metafile_page_count_ = total_page_count_;
+    // Render all pages.
+    for (int i = 0; i < total_page_count_; i++)

[Lei Zhang, 2011/09/01 05:16:51]

nit: ++i here and below.

[kmadhusu, 2011/09/01 20:21:16]

will submit a new CL to address this.

       pages_to_render_.push_back(i);
-  } else {
-    actual_page_count_ = pages.size();
-    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_) {
-        LOG(ERROR) << "CreatePreviewDocument got invalid page count "
-                << page_number << " at index " << i;
-        return false;
+  } else if (generate_draft_pages_) {
+    int pages_index = 0;

[Lei Zhang, 2011/09/01 05:16:51]

So if I understand this correctly, if the user opens a 1000 page document, then
immediately selects page 2, we'll generate a metafile for page 2, and then go
back and generate the other 999 pages immediately, rather than on-demand?

[kmadhusu, 2011/09/01 20:21:16]

Yes. We generate 999 draft pages only if required. If the browser has all the
required draft pages then we will generate only the complete metafile for the
selected page range. 

+    for (int i = 0; i < total_page_count_; i++) {
+      if (pages_index < selected_page_count && i == pages[pages_index]) {
+        pages_index++;
+        continue;
       }
-      pages_to_render_.push_back(page_number);
+      pages_to_render_.push_back(i);
     }
   }
 
   document_render_time_ = base::TimeDelta();
   begin_time_ = base::TimeTicks::Now();
 
   return true;
 }
 
 void PrintWebViewHelper::PrintPreviewContext::RenderedPreviewPage(
     const base::TimeDelta& page_time) {
   DCHECK_EQ(RENDERING, state_);
   document_render_time_ += page_time;
   UMA_HISTOGRAM_TIMES("PrintPreview.RenderPDFPageTime", page_time);
 }
 
-void PrintWebViewHelper::PrintPreviewContext::FinalizePreviewDocument() {
+void PrintWebViewHelper::PrintPreviewContext::AllPagesRendered() {
   DCHECK_EQ(RENDERING, state_);
   state_ = DONE;
+  prep_frame_view_->FinishPrinting();
+}
+
+void PrintWebViewHelper::PrintPreviewContext::FinalizePrintReadyDocument() {
+  if (state_ != DONE && state_ != RENDERING)
+    NOTREACHED();
 
   base::TimeTicks begin_time = base::TimeTicks::Now();
-
-  prep_frame_view_->FinishPrinting();
   metafile_->FinishDocument();
 
-  if (actual_page_count_ <= 0) {
+  if (print_ready_metafile_page_count_ <= 0) {
     NOTREACHED();
     return;
   }
 
   UMA_HISTOGRAM_MEDIUM_TIMES("PrintPreview.RenderToPDFTime",
                              document_render_time_);
   base::TimeDelta total_time = (base::TimeTicks::Now() - begin_time) +
                                document_render_time_;
   UMA_HISTOGRAM_MEDIUM_TIMES("PrintPreview.RenderAndGeneratePDFTime",
                              total_time);
   UMA_HISTOGRAM_MEDIUM_TIMES("PrintPreview.RenderAndGeneratePDFTimeAvgPerPage",
-                             total_time / actual_page_count_);
+                             total_time / pages_to_render_.size());
 }
 
 void PrintWebViewHelper::PrintPreviewContext::Finished() {
   DCHECK_EQ(DONE, state_);
   ClearContext();
 }
 
 void PrintWebViewHelper::PrintPreviewContext::Failed() {
   DCHECK(state_ == INITIALIZED || state_ == RENDERING);
   state_ = INITIALIZED;
   ClearContext();
 }
 
 int PrintWebViewHelper::PrintPreviewContext::GetNextPageNumber() {
   DCHECK_EQ(RENDERING, state_);
-  if (current_page_index_ >= actual_page_count_)
+  if ((size_t)(current_page_index_) == pages_to_render_.size())
     return -1;
   return pages_to_render_[current_page_index_++];
 }
 
 bool PrintWebViewHelper::PrintPreviewContext::IsReadyToRender() const {
   return state_ != UNINITIALIZED;
 }
 
 bool PrintWebViewHelper::PrintPreviewContext::IsModifiable() const {
   // TODO(vandebo) I think this should only return false if the content is a
   // PDF, just because we are printing a particular node does not mean it's
   // a PDF (right?), we should check the mime type of the node.
   if (node())
     return false;
   std::string mime(frame()->dataSource()->response().mimeType().utf8());
   return mime != "application/pdf";
 }
 
+bool PrintWebViewHelper::PrintPreviewContext::IsLastPageOfPrintReadyMetafile()
+    const {
+  return current_page_index_ == print_ready_metafile_page_count_;
+}
+
+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_;
 }
 
 WebKit::WebNode* PrintWebViewHelper::PrintPreviewContext::node() const {
   return node_.get();
 }
 
 int PrintWebViewHelper::PrintPreviewContext::total_page_count() const {
   DCHECK(IsReadyToRender());
   return total_page_count_;
 }
 
+bool PrintWebViewHelper::PrintPreviewContext::generate_draft_pages() {
+  return generate_draft_pages_;
+}
+
 printing::PreviewMetafile*
 PrintWebViewHelper::PrintPreviewContext::metafile() const {
   return metafile_.get();
 }
 
 const PrintMsg_Print_Params&
 PrintWebViewHelper::PrintPreviewContext::print_params() const {
   return *print_params_;
 }
 
 const gfx::Size&
 PrintWebViewHelper::PrintPreviewContext::GetPrintCanvasSize() const {
   return prep_frame_view_->GetPrintCanvasSize();
 }
 
 void PrintWebViewHelper::PrintPreviewContext::ClearContext() {
   prep_frame_view_.reset();
   metafile_.reset();
   pages_to_render_.clear();
 }