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

chrome/renderer/print_web_view_helper_win.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 "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/process_util.h"
@@ skipping 108 matching lines @@
   }
 
   Send(new PrintHostMsg_DidPrintPage(routing_id(), page_params));
 }
 
 void PrintWebViewHelper::RenderPreviewPage(int page_number) {
   PrintMsg_Print_Params print_params = print_preview_context_.print_params();
   // Calculate the dpi adjustment.
   float scale_factor = static_cast<float>(print_params.desired_dpi /
                                           print_params.dpi);
+  scoped_ptr<Metafile> draft_metafile;
+  printing::Metafile* initial_render_metafile =
+      print_preview_context_.metafile();
+
+  if (print_preview_context_.IsModifiable() && is_print_ready_metafile_sent_) {
+    draft_metafile.reset(new printing::PreviewMetafile);
+    initial_render_metafile = draft_metafile.get();
+  }
 
   base::TimeTicks begin_time = base::TimeTicks::Now();
   printing::Metafile* render_page_result =
       RenderPage(print_params, &scale_factor, page_number, true,
-                 print_preview_context_.frame(),
-                 print_preview_context_.metafile());
+                 print_preview_context_.frame(), initial_render_metafile);
   // In the preview flow, RenderPage will never return a new metafile.
-  DCHECK_EQ(render_page_result, print_preview_context_.metafile());
-
+  DCHECK_EQ(render_page_result, initial_render_metafile);
   print_preview_context_.RenderedPreviewPage(
       base::TimeTicks::Now() - begin_time);
 
-  scoped_ptr<printing::Metafile> page_metafile;
-  if (print_preview_context_.IsModifiable()) {
-    page_metafile.reset(
+  if (draft_metafile.get()) {
+    draft_metafile->FinishDocument();
+  } else if (print_preview_context_.IsModifiable() &&
+             print_preview_context_.generate_draft_pages()){
+    DCHECK(!draft_metafile.get());
+    draft_metafile.reset(
         print_preview_context_.metafile()->GetMetafileForCurrentPage());
   }
-  PreviewPageRendered(page_number, page_metafile.get());
+  PreviewPageRendered(page_number, draft_metafile.get());
 }
 
 Metafile* PrintWebViewHelper::RenderPage(
     const PrintMsg_Print_Params& params, float* scale_factor, int page_number,
     bool is_preview, WebFrame* frame, Metafile* metafile) {
   PageSizeMargins page_layout_in_points;
   GetPageSizeAndMarginsInPoints(frame, page_number, params,
                                 &page_layout_in_points);
 
   int width;
@@ skipping 19 matching lines @@
       static_cast<int>(page_layout_in_points.margin_top),
       static_cast<int>(page_layout_in_points.content_width),
       static_cast<int>(page_layout_in_points.content_height));
   SkDevice* device = metafile->StartPageForVectorCanvas(
       page_size, content_area, frame->getPrintPageShrink(page_number));
   DCHECK(device);
   // The printPage method may take a reference to the canvas we pass down, so it
   // can't be a stack object.
   SkRefPtr<skia::VectorCanvas> canvas = new skia::VectorCanvas(device);
   canvas->unref();  // SkRefPtr and new both took a reference.
-  if (is_preview)
+  if (is_preview) {
     printing::MetafileSkiaWrapper::SetMetafileOnCanvas(canvas.get(), metafile);
+    printing::MetafileSkiaWrapper::SetDraftMode(canvas.get(),
+                                                is_print_ready_metafile_sent_);
+  }
 
   float webkit_scale_factor = frame->printPage(page_number, canvas.get());
   if (*scale_factor <= 0 || webkit_scale_factor <= 0) {
     NOTREACHED() << "Printing page " << page_number << " failed.";
   } else {
     // Update the dpi adjustment with the "page |scale_factor|" calculated in
     // webkit.
     *scale_factor /= webkit_scale_factor;
   }
 
@@ skipping 80 matching lines @@
     shared_buf.Unmap();
     return false;
   }
   shared_buf.GiveToProcess(base::GetCurrentProcessHandle(), shared_mem_handle);
   shared_buf.Unmap();
 
   Send(new PrintHostMsg_DuplicateSection(routing_id(), *shared_mem_handle,
                                          shared_mem_handle));
   return true;
 }