Refactor win printing workflow.

chrome/renderer/print_web_view_helper_win.cc

Index: chrome/renderer/print_web_view_helper_win.cc
diff --git a/chrome/renderer/print_web_view_helper_win.cc b/chrome/renderer/print_web_view_helper_win.cc
index 286e801610071d418fa2ce693ec073432377ca4a..9e7c63018c3d3cc6777ac79c936b39cc4b3707a3 100644
--- a/chrome/renderer/print_web_view_helper_win.cc
+++ b/chrome/renderer/print_web_view_helper_win.cc
@@ -1,10 +1,11 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// 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/process_util.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/render_messages_params.h"
 #include "chrome/renderer/render_view.h"
@@ -66,12 +67,11 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
                                    const gfx::Size& canvas_size,
                                    WebFrame* frame) {
   // Generate a memory-based metafile. It will use the current screen's DPI.
-  printing::NativeMetafile metafile;
-
-  metafile.CreateDc(NULL, NULL);
-  HDC hdc = metafile.hdc();
-  DCHECK(hdc);
-  skia::PlatformDevice::InitializeDC(hdc);
+  // Each metafile contains a single page.
+  scoped_ptr<printing::NativeMetafile> metafile(new printing::NativeMetafile());
+  metafile->CreateDc(NULL, NULL);
+  DCHECK(metafile->hdc());
+  skia::PlatformDevice::InitializeDC(metafile->hdc());
 
   int page_number = params.page_number;
 
@@ -88,10 +88,44 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
   // Since WebKit extends the page width depending on the magical |scale_factor|
   // we make sure the canvas covers the worst case scenario (x2.0 currently).
   // PrintContext will then set the correct clipping region.
-  int width = static_cast<int>(content_width_in_points *
-                               params.params.max_shrink);
-  int height = static_cast<int>(content_height_in_points *
-                                params.params.max_shrink);
+  gfx::Size page_size(
+      static_cast<int>(content_width_in_points * params.params.max_shrink),
+      static_cast<int>(content_height_in_points * params.params.max_shrink));
+
+  // Render page for printing.
+  RenderPage(page_size, &scale_factor, page_number, frame, &metafile,
+      params.params.supports_alpha_blend);
+
+  // Close the device context to retrieve the compiled metafile.
+  if (!metafile->CloseDc())
+    NOTREACHED();
+
+  ViewHostMsg_DidPrintPage_Params page_params;
+  page_params.data_size = metafile->GetDataSize();
+  page_params.page_number = page_number;
+  page_params.document_cookie = params.params.document_cookie;
+  page_params.actual_shrink = scale_factor;
+  page_params.page_size = params.params.page_size;
+  page_params.content_area = gfx::Rect(params.params.margin_left,
+      params.params.margin_top, params.params.printable_size.width(),
+      params.params.printable_size.height());
+  page_params.has_visible_overlays = frame->isPageBoxVisible(page_number);
+
+  if (CopyMetafileDataToSharedMem(metafile,
+          &(page_params.metafile_data_handle))) {
+    Send(new ViewHostMsg_DidPrintPage(routing_id(), page_params));
+  }
+}
+
+void PrintWebViewHelper::RenderPage(
+    const gfx::Size& page_size, float* scale_factor, int page_number,
+    WebFrame* frame, scoped_ptr<printing::NativeMetafile>* metafile,
+    bool supports_alpha_blend) {
+  HDC hdc = (*metafile)->hdc();
+  DCHECK(hdc);
+
+  int width = page_size.width();
+  int height = page_size.height();
 #if 0
   // TODO(maruel): This code is kept for testing until the 100% GDI drawing
   // code is stable. maruels use this code's output as a reference when the
@@ -101,12 +135,12 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
   skia::PlatformCanvas canvas(width, height, true);
   canvas.drawARGB(255, 255, 255, 255, SkXfermode::kSrc_Mode);
   float webkit_scale_factor = frame->printPage(page_number, &canvas);
-  if (scale_factor <= 0 || webkit_scale_factor <= 0) {
+  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;
+    // Update the dpi adjustment with the "page |scale_factor|" calculated in
+    // webkit.
+    *scale_factor /= webkit_scale_factor;
   }
 
   // Create a BMP v4 header that we can serialize.
@@ -129,26 +163,24 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
   // 100% GDI based.
   skia::VectorCanvas canvas(hdc, width, height);
   float webkit_scale_factor = frame->printPage(page_number, &canvas);
-  if (scale_factor <= 0 || webkit_scale_factor <= 0) {
+  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;
+    // Update the dpi adjustment with the "page |scale_factor|" calculated in
+    // webkit.
+    *scale_factor /= webkit_scale_factor;
   }
 #endif
 
-  // Done printing. Close the device context to retrieve the compiled metafile.
-  if (!metafile.CloseDc()) {
-    NOTREACHED() << "metafile failed";
-  }
-  printing::NativeMetafile* mf = &metafile;
-  printing::NativeMetafile metafile2;
-
   skia::VectorPlatformDevice* platform_device =
-    static_cast<skia::VectorPlatformDevice*>(canvas.getDevice());
-  if (platform_device->alpha_blend_used() &&
-      !params.params.supports_alpha_blend) {
+      static_cast<skia::VectorPlatformDevice*>(canvas.getDevice());
+  if (platform_device->alpha_blend_used() && !supports_alpha_blend) {
+    // Close the device context to retrieve the compiled metafile.
+    if (!(*metafile)->CloseDc())
+      NOTREACHED();
+
+    scoped_ptr<printing::NativeMetafile> metafile2(
+        new printing::NativeMetafile());
     // Page used alpha blend, but printer doesn't support it.  Rewrite the
     // metafile and flatten out the transparency.
     HDC bitmap_dc = CreateCompatibleDC(GetDC(NULL));
@@ -170,45 +202,32 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
     HBRUSH whiteBrush = static_cast<HBRUSH>(GetStockObject(WHITE_BRUSH));
     FillRect(bitmap_dc, &rect, whiteBrush);
 
-    metafile2.CreateDc(NULL, NULL);
-    HDC hdc = metafile2.hdc();
+    metafile2->CreateDc(NULL, NULL);
+    HDC hdc = metafile2->hdc();
     DCHECK(hdc);
     skia::PlatformDevice::InitializeDC(hdc);
 
-    RECT metafile_bounds = metafile.GetBounds().ToRECT();
+    RECT metafile_bounds = (*metafile)->GetBounds().ToRECT();
     // Process the old metafile, placing all non-AlphaBlend calls into the
     // new metafile, and copying the results of all the AlphaBlend calls
     // from the bitmap DC.
     EnumEnhMetaFile(hdc,
-                    metafile.emf(),
+                    (*metafile)->emf(),
                     EnhMetaFileProc,
                     &bitmap_dc,
                     &metafile_bounds);
 
     SelectObject(bitmap_dc, old_bitmap);
-
-    if (!metafile2.CloseDc()) {
-      NOTREACHED() << "metafile failed";
-    }
-    mf = &metafile2;
+    (*metafile)->CloseEmf();

[vandebo (ex-Chrome), 2011/01/24 17:39:18]

nit: Not neded.  metafile->reset will destruct *metafile, which calls
CloseEmf().

[kmadhusu, 2011/01/24 22:26:04]

Fixed.

+    metafile->reset(metafile2.release());
   }
+}
 
-  // Get the size of the compiled metafile.
-  uint32 buf_size = mf->GetDataSize();
-  DCHECK_GT(buf_size, 128u);

[vandebo (ex-Chrome), 2011/01/24 17:39:18]

nit: You've lost this DCHECK

[kmadhusu, 2011/01/24 22:26:04]

Fixed.

-  ViewHostMsg_DidPrintPage_Params page_params;
-  page_params.data_size = 0;
-  page_params.metafile_data_handle = NULL;

[vandebo (ex-Chrome), 2011/01/24 17:39:18]

This will lead to a different control flow than you have for the >350MB case.

[kmadhusu, 2011/01/24 22:26:04]

Added "page_params.metafile_data_handle = NULL" statement.

-  page_params.page_number = page_number;
-  page_params.document_cookie = params.params.document_cookie;
-  page_params.actual_shrink = scale_factor;
-  page_params.page_size = params.params.page_size;
-  page_params.content_area = gfx::Rect(params.params.margin_left,
-      params.params.margin_top, params.params.printable_size.width(),
-      params.params.printable_size.height());
-  page_params.has_visible_overlays = frame->isPageBoxVisible(page_number);
+bool PrintWebViewHelper::CopyMetafileDataToSharedMem(
+    scoped_ptr<printing::NativeMetafile>& metafile,

[vandebo (ex-Chrome), 2011/01/24 17:39:18]

Pass the raw pointer, not a scoped_ptr<>&.

[kmadhusu, 2011/01/24 22:26:04]

Done.

+    base::SharedMemoryHandle* shared_mem_handle) {
+  uint32 buf_size = metafile->GetDataSize();
   base::SharedMemory shared_buf;
-
   // http://msdn2.microsoft.com/en-us/library/ms535522.aspx
   // Windows 2000/XP: When a page in a spooled file exceeds approximately 350
   // MB, it can fail to print and not send an error message.
@@ -216,9 +235,9 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
     // Allocate a shared memory buffer to hold the generated metafile data.
     if (shared_buf.CreateAndMapAnonymous(buf_size)) {
       // Copy the bits into shared memory.
-      if (mf->GetData(shared_buf.memory(), buf_size)) {
-        page_params.metafile_data_handle = shared_buf.handle();
-        page_params.data_size = buf_size;
+      if (metafile->GetData(shared_buf.memory(), buf_size)) {
+        shared_buf.GiveToProcess(base::GetCurrentProcessHandle(),
+                                 shared_mem_handle);
       } else {
         NOTREACHED() << "GetData() failed";
       }
@@ -229,13 +248,7 @@ void PrintWebViewHelper::PrintPage(const ViewMsg_PrintPage_Params& params,
   } else {
     NOTREACHED() << "Buffer too large: " << buf_size;
   }
-  mf->CloseEmf();
-  if (Send(new ViewHostMsg_DuplicateSection(
-      routing_id(),
-      page_params.metafile_data_handle,
-      &page_params.metafile_data_handle))) {
-    if (!is_preview_) {
-      Send(new ViewHostMsg_DidPrintPage(routing_id(), page_params));
-    }
-  }
+  metafile->CloseEmf();
+  return (Send(new ViewHostMsg_DuplicateSection(routing_id(),
+               *shared_mem_handle, shared_mem_handle)));
 }