Fix generation of the complete metafile for print preview flow.

chrome/renderer/print_web_view_helper_mac.mm

 // 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"
 
 #import <AppKit/AppKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
@@ skipping 50 matching lines @@
 
 void PrintWebViewHelper::RenderPreviewPage(int page_number) {
   float scale_factor = print_preview_context_.frame()->getPrintPageShrink(0);
   PrintMsg_Print_Params printParams = print_preview_context_.print_params();
   gfx::Rect content_area(printParams.margin_left, printParams.margin_top,
                          printParams.printable_size.width(),
                          printParams.printable_size.height());
 
   printing::Metafile* initial_render_metafile =
       print_preview_context_.metafile();
-  scoped_ptr<printing::Metafile> draft_metafile;
+  scoped_ptr<printing::PreviewMetafile> draft_metafile;
 #if !defined(USE_SKIA)
   if (print_preview_context_.IsModifiable()) {
     draft_metafile.reset(new printing::PreviewMetafile);
     if (!draft_metafile->Init()) {
       DidFinishPrinting(FAIL_PREVIEW);
       return;
     }
     initial_render_metafile = draft_metafile.get();
   }
 #endif
 
   base::TimeTicks begin_time = base::TimeTicks::Now();
   RenderPage(printParams.page_size, content_area, scale_factor, page_number,
              print_preview_context_.frame(), initial_render_metafile);
   print_preview_context_.RenderedPreviewPage(
       base::TimeTicks::Now() - begin_time);
 
   if (print_preview_context_.IsModifiable()) {
 #if defined(USE_SKIA)
     DCHECK(!draft_metafile.get());
     draft_metafile.reset(reinterpret_cast<printing::PreviewMetafile*>(
         print_preview_context_.metafile())->GetMetafileForCurrentPage());
 #else
     draft_metafile->FinishDocument();
 
     // With CG, we rendered into a new metafile so we could get it as a draft
     // document.  Now we need to add it to complete document.
+    printing::Metafile* complete_metafile = print_preview_context_.metafile();
+    bool success = complete_metafile->StartPage(
+        printParams.page_size, gfx::Rect(printParams.page_size), 1.0);

[kmadhusu, 2011/08/05 23:33:52]

Please document that the scale factor is always 1.0.

[kmadhusu, 2011/08/05 23:33:52]

Why can't we use the content_area rather than
"gfx::Rect(printParams.page_size)"?

[vandebo (ex-Chrome), 2011/08/06 00:43:43]

Done.

[vandebo (ex-Chrome), 2011/08/06 00:43:43]

Because we want a 1:1 rendering of the source PDF, we need to draw into the
entire page (arg I've specified), not the content area (smaller).

+    DCHECK(success);
+    // StartPage unconditionally flips the content over, flip it back since it
+    // was already flipped in draft_metafile.
+    CGContextTranslateCTM(complete_metafile->context(), 0,
+                          printParams.page_size.height());
+    CGContextScaleCTM(complete_metafile->context(), 1.0, -1.0);
+
     draft_metafile->RenderPage(1,
-                               print_preview_context_.metafile()->context(),
-                               CGRectMake(content_area.x(), content_area.y(),
-                                          content_area.width(),
-                                          content_area.height()),
-                               false /*shrunk_to_fit*/,
+                               complete_metafile->context(),
+                               draft_metafile->GetPageBounds(1).ToCGRect(),
+                               false /*shrink_to_fit*/,

[kmadhusu, 2011/08/05 23:33:52]

style nit: Add a space after "/*" and before "*/".

[vandebo (ex-Chrome), 2011/08/06 00:43:43]

Done.

                                false /*stretch_to_fit*/,
                                true /*center_horizontally*/,
                                true /*center_vertically*/);
+    complete_metafile->FinishPage();
 #endif
   }
 
   PreviewPageRendered(page_number, draft_metafile.get());
 }
 
 void PrintWebViewHelper::RenderPage(
     const gfx::Size& page_size, const gfx::Rect& content_area,
     const float& scale_factor, int page_number, WebFrame* frame,
     printing::Metafile* metafile) {
@@ skipping 18 matching lines @@
     base::mac::ScopedNSAutoreleasePool pool;
     CGContextRef cgContext = metafile->context();
     CGContextRef canvasPtr = cgContext;
 #endif
     frame->printPage(page_number, canvasPtr);
   }
 
   // Done printing. Close the device context to retrieve the compiled metafile.
   metafile->FinishPage();
 }