printed_document.h

// Copyright (c) 2012 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.

#ifndef PRINTING_PRINTED_DOCUMENT_H_
#define PRINTING_PRINTED_DOCUMENT_H_

#include <map>

#include "base/memory/ref_counted.h"
#include "base/string16.h"
#include "base/synchronization/lock.h"
#include "printing/print_settings.h"
#include "ui/gfx/native_widget_types.h"

class MessageLoop;

namespace base {
class FilePath;
}

namespace printing {

class Metafile;
class PrintedPage;
class PrintedPagesSource;
class PrintingContext;

// A collection of rendered pages. The settings are immutable. If the print
// settings are changed, a new PrintedDocument must be created.
// Warning: May be accessed from many threads at the same time. Only one thread
// will have write access. Sensible functions are protected by a lock.
// Warning: Once a page is loaded, it cannot be replaced. Pages may be discarded
// under low memory conditions.
class PRINTING_EXPORT PrintedDocument
    : public base::RefCountedThreadSafe<PrintedDocument> {
 public:
  // The cookie shall be unique and has a specific relationship with its
  // originating source and settings.
  PrintedDocument(const PrintSettings& settings,
                  PrintedPagesSource* source,
                  int cookie);

  // Sets a page's data. 0-based. Takes metafile ownership.
  // Note: locks for a short amount of time.
  void SetPage(int page_number, Metafile* metafile, double shrink,
               const gfx::Size& paper_size, const gfx::Rect& page_rect);

  // Retrieves a page. If the page is not available right now, it
  // requests to have this page be rendered and returns false.
  // Note: locks for a short amount of time.
  bool GetPage(int page_number, scoped_refptr<PrintedPage>* page);

  // Draws the page in the context.
  // Note: locks for a short amount of time in debug only.
#if defined(OS_WIN) || defined(OS_MACOSX) && !defined(USE_AURA)
  void RenderPrintedPage(const PrintedPage& page,
                         gfx::NativeDrawingContext context) const;
#elif defined(OS_POSIX)
  void RenderPrintedPage(const PrintedPage& page,
                         PrintingContext* context) const;
#endif

  // Returns true if all the necessary pages for the settings are already
  // rendered.
  // Note: locks while parsing the whole tree.
  bool IsComplete() const;

  // Disconnects the PrintedPage source (PrintedPagesSource). It is done when
  // the source is being destroyed.
  void DisconnectSource();

  // Retrieves the current memory usage of the renderer pages.
  // Note: locks for a short amount of time.
  uint32 MemoryUsage() const;

  // Sets the number of pages in the document to be rendered. Can only be set
  // once.
  // Note: locks for a short amount of time.
  void set_page_count(int max_page);

  // Number of pages in the document. Used for headers/footers.
  // Note: locks for a short amount of time.
  int page_count() const;

  // Returns the number of expected pages to be rendered. It is a non-linear
  // series if settings().ranges is not empty. It is the same value as
  // document_page_count() otherwise.
  // Note: locks for a short amount of time.
  int expected_page_count() const;

  // Getters. All these items are immutable hence thread-safe.
  const PrintSettings& settings() const { return immutable_.settings_; }
  const string16& name() const { return immutable_.name_; }
  int cookie() const { return immutable_.cookie_; }

  // Sets a path where to dump printing output files for debugging. If never set
  // no files are generated.
  static void set_debug_dump_path(const base::FilePath& debug_dump_path);

  static const base::FilePath& debug_dump_path();

 private:
  friend class base::RefCountedThreadSafe<PrintedDocument>;

  virtual ~PrintedDocument();

  // Array of data for each print previewed page.
  typedef std::map<int, scoped_refptr<PrintedPage> > PrintedPages;

  // Contains all the mutable stuff. All this stuff MUST be accessed with the
  // lock held.
  struct Mutable {
    explicit Mutable(PrintedPagesSource* source);
    ~Mutable();

    // Source that generates the PrintedPage's (i.e. a TabContents). It will be
    // set back to NULL if the source is deleted before this object.
    PrintedPagesSource* source_;

    // Contains the pages' representation. This is a collection of PrintedPage.
    // Warning: Lock must be held when accessing this member.
    PrintedPages pages_;

    // Number of expected pages to be rendered.
    // Warning: Lock must be held when accessing this member.
    int expected_page_count_;

    // The total number of pages in the document.
    int page_count_;

#if defined(OS_POSIX) && !defined(OS_MACOSX)
    // Page number of the first page.
    int first_page;
#endif
  };

  // Contains all the immutable stuff. All this stuff can be accessed without
  // any lock held. This is because it can't be changed after the object's
  // construction.
  struct Immutable {
    Immutable(const PrintSettings& settings, PrintedPagesSource* source,
              int cookie);
    ~Immutable();

    // Print settings used to generate this document. Immutable.
    PrintSettings settings_;

    // Native thread for the render source.
    MessageLoop* source_message_loop_;

    // Document name. Immutable.
    string16 name_;

    // Cookie to uniquely identify this document. It is used to make sure that a
    // PrintedPage is correctly belonging to the PrintedDocument. Since
    // PrintedPage generation is completely asynchronous, it could be easy to
    // mess up and send the page to the wrong document. It can be viewed as a
    // simpler hash of PrintSettings since a new document is made each time the
    // print settings change.
    int cookie_;
  };

  void DebugDump(const PrintedPage& page);

  // All writable data member access must be guarded by this lock. Needs to be
  // mutable since it can be acquired from const member functions.
  mutable base::Lock lock_;

  // All the mutable members.
  Mutable mutable_;

  // All the immutable members.
  const Immutable immutable_;

  DISALLOW_COPY_AND_ASSIGN(PrintedDocument);
};

}  // namespace printing

#endif  // PRINTING_PRINTED_DOCUMENT_H_