add print to pdf for headless

headless/lib/browser/headless_print_manager.cc

+// Copyright 2017 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 "headless/lib/browser/headless_print_manager.h"
+
+#include <utility>
+#include <vector>
+
+#include "base/base64.h"
+#include "components/printing/browser/print_manager_utils.h"
+#include "components/printing/common/print_messages.h"
+#include "printing/pdf_metafile_skia.h"
+#include "printing/print_settings.h"
+#include "printing/units.h"
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(printing::HeadlessPrintManager);
+
+namespace printing {
+
+namespace {
+
+// TODO(jzfeng): let the print settings to be configurable.
+const double kTopMarginInInch = 0.25;
+const double kBottomMarginInInch = 0.56;
+const double kLeftMarginInInch = 0.25;
+const double kRightMarginInInch = 0.25;
+
+PrintSettings GetDefaultPDFPrinterSettings() {
+#if defined(OS_MACOSX)
+  int dpi = kPointsPerInch;

[Lei Zhang, 2017/04/06 08:08:42]

Copy over the comment from GetDpi() to explain why we do this here.

[jzfeng, 2017/04/06 09:01:51]

Done.

+#else
+  int dpi = kDefaultPdfDpi;
+#endif
+  gfx::Size physical_size_device_units;
+  gfx::Rect printable_area_device_units;
+  double page_width_in_pixel = kLetterWidthInch * dpi;
+  double page_height_in_pixel = kLetterHeightInch * dpi;
+  physical_size_device_units.SetSize(static_cast<int>(page_width_in_pixel),
+                                     static_cast<int>(page_height_in_pixel));
+  printable_area_device_units.SetRect(
+      static_cast<int>(kLeftMarginInInch * dpi),
+      static_cast<int>(kTopMarginInInch * dpi),
+      page_width_in_pixel - (kLeftMarginInInch + kRightMarginInInch) * dpi,
+      page_height_in_pixel - (kTopMarginInInch + kBottomMarginInInch) * dpi);
+
+  PrintSettings settings;
+  settings.set_dpi(dpi);
+  settings.SetPrinterPrintableArea(physical_size_device_units,
+                                   printable_area_device_units, true);
+  settings.set_should_print_backgrounds(true);
+  return settings;
+}
+
+}  // namespace
+
+HeadlessPrintManager::HeadlessPrintManager(content::WebContents* web_contents)
+    : PrintManager(web_contents) {
+  Reset();
+}
+
+HeadlessPrintManager::~HeadlessPrintManager() {}
+
+// static
+std::string HeadlessPrintManager::PrintResultToString(PrintResult result) {
+  switch (result) {
+    case PRINT_SUCCESS:
+      return std::string();  // no error message
+    case PRINTING_FAILED:
+      return "PrintingFailed";
+    case INVALID_PRINTER_SETTINGS:
+      return "ShowInvalidPrinterSettingsError";
+    case INVALID_MEMORY_HANDLE:
+      return "Invalid memory handle";

[Lei Zhang, 2017/04/06 08:08:42]

The ones above this DoNotHaveSpaces.

[jzfeng, 2017/04/06 09:01:51]

Done.

+    case METAFILE_MAP_ERROR:
+      return "Map to SharedMemory error";
+    case UNEXPECTED_VALID_MEMORY_HANDLE:
+      return "Unexpected valide memory handle";
+    case METAFILE_INVALID_HEADER:
+      return "Invalid metafile header";
+    case METAFILE_GET_DATA_ERROR:
+      return "Get data from metafile error";
+    case SIMULTANEOUS_PRINT_ACTIVE:
+      return "The previous printing job hasn't finished";
+    default:
+      NOTREACHED();
+      return "Unknown PrintResult";
+  }
+}
+
+// static
+std::unique_ptr<base::DictionaryValue>
+HeadlessPrintManager::PDFContentsToDictionaryValue(const std::string& data) {
+  std::string base_64_data;
+  base::Base64Encode(data, &base_64_data);
+  auto result = base::MakeUnique<base::DictionaryValue>();
+  result->SetString("data", base_64_data);
+  return result;
+}
+
+void HeadlessPrintManager::GetPDFContents(content::RenderFrameHost* rfh,
+                                          const GetPDFCallback& callback) {
+  DCHECK(callback);
+  if (!callback_.is_null()) {

[Lei Zhang, 2017/04/06 08:08:42]

I think you can write: if (callback_) {, just like the line above.

[jzfeng, 2017/04/06 09:01:51]

Done.

+    callback.Run(SIMULTANEOUS_PRINT_ACTIVE, std::string());
+    return;
+  }
+  printing_rfh_ = rfh;
+  callback_ = callback;
+  rfh->Send(new PrintMsg_PrintPages(rfh->GetRoutingID()));
+}
+
+bool HeadlessPrintManager::OnMessageReceived(
+    const IPC::Message& message,
+    content::RenderFrameHost* render_frame_host) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(HeadlessPrintManager, message)
+    IPC_MESSAGE_HANDLER(PrintHostMsg_ShowInvalidPrinterSettingsError,
+                        OnShowInvalidPrinterSettingsError)
+    IPC_MESSAGE_HANDLER(PrintHostMsg_DidPrintPage, OnDidPrintPage)
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(PrintHostMsg_GetDefaultPrintSettings,
+                                    OnGetDefaultPrintSettings)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled || PrintManager::OnMessageReceived(message, render_frame_host);
+}
+
+void HeadlessPrintManager::OnGetDefaultPrintSettings(IPC::Message* reply_msg) {
+  PrintMsg_Print_Params print_params;
+  RenderParamsFromPrintSettings(GetDefaultPDFPrinterSettings(), &print_params);
+  print_params.document_cookie = PrintSettings::NewCookie();
+  PrintHostMsg_GetDefaultPrintSettings::WriteReplyParams(reply_msg,
+                                                         print_params);
+  printing_rfh_->Send(reply_msg);
+}
+
+void HeadlessPrintManager::OnShowInvalidPrinterSettingsError() {
+  ReleaseJob(INVALID_PRINTER_SETTINGS);
+}
+
+void HeadlessPrintManager::OnPrintingFailed(int cookie) {
+  ReleaseJob(PRINTING_FAILED);
+}
+
+void HeadlessPrintManager::OnDidPrintPage(
+    const PrintHostMsg_DidPrintPage_Params& params) {

[Lei Zhang, 2017/04/06 08:08:42]

Add a check to defend against spurious messages:

if (!callback_)
  return; 

[jzfeng, 2017/04/06 09:01:51]

Use DCHECK instead, since callback_ should not be null.

[Eric Seckler, 2017/04/06 09:14:25]

I believe Lei meant that we shouldn't trust the renderer to send this message
only when we expect it. Thus, callback_ might not be set. In such a case, we
don't want to crash the browser process - maybe add a DLOG(ERROR) instead.

[jzfeng, 2017/04/07 03:24:06]

Thanks for the explanation! Done.

+  const bool metafile_must_be_valid = expecting_first_page_;
+  expecting_first_page_ = false;
+
+  // Only used when |metafile_must_be_valid| is true.
+  std::unique_ptr<base::SharedMemory> shared_buf;
+  if (metafile_must_be_valid) {
+    if (!base::SharedMemory::IsHandleValid(params.metafile_data_handle)) {
+      ReleaseJob(INVALID_MEMORY_HANDLE);
+      return;
+    }
+    shared_buf =
+        base::MakeUnique<base::SharedMemory>(params.metafile_data_handle, true);
+    if (!shared_buf->Map(params.data_size)) {
+      ReleaseJob(METAFILE_MAP_ERROR);
+      return;
+    }
+  } else {
+    if (base::SharedMemory::IsHandleValid(params.metafile_data_handle)) {
+      base::SharedMemory::CloseHandle(params.metafile_data_handle);
+      ReleaseJob(UNEXPECTED_VALID_MEMORY_HANDLE);
+      return;
+    }
+  }
+
+  auto metafile = base::MakeUnique<PdfMetafileSkia>(PDF_SKIA_DOCUMENT_TYPE);

[Lei Zhang, 2017/04/06 08:08:42]

You can merge this block of code with the if (metafile_must_be_valid) block
above. Unlike the normal printing code, you don't need |metafile| to have this
scoped. Neither does |shared_buf| once you do this.

[jzfeng, 2017/04/06 09:01:51]

Good catch! Done.

+  if (metafile_must_be_valid) {
+    if (!metafile->InitFromData(shared_buf->memory(), params.data_size)) {
+      ReleaseJob(METAFILE_INVALID_HEADER);
+      return;
+    }
+    std::vector<char> buffer;
+    if (!metafile->GetDataAsVector(&buffer)) {
+      ReleaseJob(METAFILE_GET_DATA_ERROR);
+      return;
+    }
+    data_ = std::string(buffer.data(), buffer.size());
+  }
+
+  if (--number_pages_ == 0)
+    ReleaseJob(PRINT_SUCCESS);
+}
+
+void HeadlessPrintManager::Reset() {
+  printing_rfh_ = nullptr;
+  callback_.Reset();
+  data_.clear();
+  expecting_first_page_ = true;
+  number_pages_ = 0;
+}
+
+void HeadlessPrintManager::ReleaseJob(PrintResult result) {

[Lei Zhang, 2017/04/06 08:08:42]

Add a check to defend against spurious messages here too. Otherwise, if
ReleaseJob() gets triggered twice, the second call will crash while trying to
run the callback.

[jzfeng, 2017/04/06 09:01:51]

Done.

[Eric Seckler, 2017/04/06 09:14:25]

Same here, DCHECK doesn't protect us from spurious messages :)

[jzfeng, 2017/04/07 03:24:06]

Done.

+  if (result == PRINT_SUCCESS)
+    callback_.Run(result, std::move(data_));
+  else
+    callback_.Run(result, std::string());
+  printing_rfh_->Send(new PrintMsg_PrintingDone(printing_rfh_->GetRoutingID(),
+                                                result == PRINT_SUCCESS));
+  Reset();
+}
+
+}  // namespace printing