Printing on Windows via PDF

chrome/utility/chrome_content_utility_client.cc

Index: chrome/utility/chrome_content_utility_client.cc
diff --git a/chrome/utility/chrome_content_utility_client.cc b/chrome/utility/chrome_content_utility_client.cc
index 7390adb3e50d85838ae4d1e3f79037af7f2f7723..465698f4114aabc710ed665b5bf4133b6f829319 100644
--- a/chrome/utility/chrome_content_utility_client.cc
+++ b/chrome/utility/chrome_content_utility_client.cc
@@ -365,6 +365,8 @@ bool ChromeContentUtilityClient::OnMessageReceived(
     IPC_MESSAGE_HANDLER(ChromeUtilityMsg_DecodeImageBase64, OnDecodeImageBase64)
     IPC_MESSAGE_HANDLER(ChromeUtilityMsg_RenderPDFPagesToMetafile,
                         OnRenderPDFPagesToMetafile)
+    IPC_MESSAGE_HANDLER(ChromeUtilityMsg_RenderPDFPagesToMetafileHandles,
+                        OnRenderPDFPagesToMetafileHandles)
     IPC_MESSAGE_HANDLER(ChromeUtilityMsg_RenderPDFPagesToPWGRaster,
                         OnRenderPDFPagesToPWGRaster)
     IPC_MESSAGE_HANDLER(ChromeUtilityMsg_RobustJPEGDecodeImage,
@@ -590,6 +592,36 @@ void ChromeContentUtilityClient::OnRenderPDFPagesToMetafile(
   ReleaseProcessIfNeeded();
 }
 
+void ChromeContentUtilityClient::OnRenderPDFPagesToMetafileHandles(
+    IPC::PlatformFileForTransit pdf_transit,
+    IPC::PlatformFileForTransit metafile_transit,
+    const printing::PdfRenderSettings& settings,
+    const std::vector<printing::PageRange>& page_ranges) {
+  bool succeeded = false;
+#if defined(OS_WIN)
+  int highest_rendered_page_number = 0;
+  double scale_factor = 1.0;
+  base::PlatformFile pdf =
+      IPC::PlatformFileForTransitToPlatformFile(pdf_transit);
+  base::PlatformFile metafile =
+      IPC::PlatformFileForTransitToPlatformFile(metafile_transit);
+  succeeded = RenderPDFToWinMetafileHandles(pdf,
+                                            metafile,
+                                            settings,
+                                            page_ranges,
+                                            &highest_rendered_page_number,
+                                            &scale_factor);
+  if (succeeded) {
+    Send(new ChromeUtilityHostMsg_RenderPDFPagesToMetafile_Succeeded(
+        highest_rendered_page_number, scale_factor));
+  }
+#endif  // defined(OS_WIN)
+  if (!succeeded) {
+    Send(new ChromeUtilityHostMsg_RenderPDFPagesToMetafile_Failed());
+  }
+  ReleaseProcessIfNeeded();
+}
+
 void ChromeContentUtilityClient::OnRenderPDFPagesToPWGRaster(
     IPC::PlatformFileForTransit pdf_transit,
     const printing::PdfRenderSettings& settings,
@@ -615,6 +647,24 @@ bool ChromeContentUtilityClient::RenderPDFToWinMetafile(
     const std::vector<printing::PageRange>& page_ranges,
     int* highest_rendered_page_number,
     double* scale_factor) {
+  base::File metafile;
+  metafile.Initialize(metafile_path,
+                      base::File::FLAG_CREATE_ALWAYS | base::File::FLAG_APPEND);
+  return RenderPDFToWinMetafileHandles(pdf_file,
+                                       metafile.GetPlatformFile(),
+                                       settings,
+                                       page_ranges,
+                                       highest_rendered_page_number,
+                                       scale_factor);
+}
+
+bool ChromeContentUtilityClient::RenderPDFToWinMetafileHandles(
+    base::PlatformFile pdf_file,
+    base::PlatformFile metafile_file,
+    const printing::PdfRenderSettings& settings,
+    const std::vector<printing::PageRange>& page_ranges,
+    int* highest_rendered_page_number,
+    double* scale_factor) {
   *highest_rendered_page_number = -1;
   *scale_factor = 1.0;
   base::win::ScopedHandle file(pdf_file);
@@ -644,7 +694,7 @@ bool ChromeContentUtilityClient::RenderPDFToWinMetafile(
   }
 
   printing::Emf metafile;
-  metafile.InitToFile(metafile_path);
+  metafile.Init();
   // We need to scale down DC to fit an entire page into DC available area.
   // Current metafile is based on screen DC and have current screen size.
   // Writing outside of those boundaries will result in the cut-off output.
@@ -680,6 +730,13 @@ bool ChromeContentUtilityClient::RenderPDFToWinMetafile(
     }
   }
   metafile.FinishDocument();
+
+  uint32 final_size = metafile.GetDataSize();
+  scoped_ptr<char[]> final_buffer(new char[final_size]);
+  CHECK(metafile.GetData(final_buffer.get(), final_size));
+  CHECK_EQ(static_cast<int>(final_size),

[Vitaly Buka (NO REVIEWS), 2014/04/25 22:35:24]

This could be huge, metafile keeps images uncompressed.
browser<->renderer uses metafile per page, and there is bugs when it can't
allocate +200MB of shared memory for page.
You can just write stream size+page_data,size+page_data,size+page_data.

[scottmg, 2014/04/25 23:07:18]

Sorry, I'm not sure what you mean here. You mean converting an EMF one page at a
time here, and then merging them somehow? The only EMF data retrieval function
seems to be for the whole file.

I'm looking at a spec here http://www.schnarff.com/file-formats/emf/[MS-EMF].pdf
it looks a bit involved to merge multiple EMF (or would at least need some
record parsing it looks like).

Or do you mean it needs to do the kMetafileMaxSize path and use
RasterizeMetafile instead?

[Vitaly Buka (NO REVIEWS), 2014/04/28 06:47:33]

It's not about rasterize.

You don't need to try to create single readable metafile like in spec.
Just concatenate them, and split on other side spooling to printers:

for (int page_number = iter->from; page_number <= iter->to; ++page_number) {
  printing::Emf metafile;
  metafile.Init();
  
  ... print one page ...
  
  base::WritePlatformFile(size);
  base::WritePlatformFile(metafile_file, 0, final_buffer.get(), final_size));
}


Ideal approach is to start Utility process in batch mode, open PDF doc once
and then request each page with separate IPC message. So we will have only one
page on disk in time, and we would able to spool the first page sooner.

I recently noticed that the same in cloud print implemented even without batch
mode. It has parameter page_range, but it always single page. Without batch mode
it just re-opens PDF for each page, inefficient.

[Vitaly Buka (NO REVIEWS), 2014/04/28 06:49:07]

base::WritePlatformFile -> base::WritePlatformFileAtCurrentPos to append

On 2014/04/28 06:47:33, Vitaly Buka wrote:

+           base::WritePlatformFile(
+               metafile_file, 0, final_buffer.get(), final_size));
   return ret;
 }
 #endif  // defined(OS_WIN)