Cgu::TextPrintManager Class Reference

A class to print plain text using the GTK print system. More...

`#include <c++-gtk-utils/text_print_manager.h>`

Inheritance diagram for Cgu::TextPrintManager:

## Public Member Functions

| TextPrintManager (const TextPrintManager &)=delete
TextPrintManager & | operator= (const TextPrintManager &)=delete
bool | set_text (std::unique_ptr< std::string > &text)
bool | print ()
bool | view ()
bool | print_to_file (const char *filename)
| ~TextPrintManager ()
Public Member Functions inherited from Cgu::IntrusiveLockCounter
| IntrusiveLockCounter (const IntrusiveLockCounter &)=delete
IntrusiveLockCounter & | operator= (const IntrusiveLockCounter &)=delete
void | ref () noexcept
void | unref ()
| IntrusiveLockCounter ()
virtual | ~IntrusiveLockCounter ()

## Static Public Member Functions

static Cgu::IntrusivePtr< Cgu::TextPrintManager > | create_manager (GtkWindow *parent=0, const std::string &font_family="", int font_size=0)
static void | page_setup (GtkWindow *parent=0)

## Detailed Description

A class to print plain text using the GTK print system.

The TextPrintManager class prints text (say, from a GtkTextBuffer object or from a plain text file) using the GTK printer interface. To obtain a TextPrintManager object, call TextPrintManager::create_manager(). TextPrintManager::set_text() passes the text to be printed. The text passed with TextPrintManager::set_text() must form valid UTF-8 (all ASCII characters form valid UTF-8). To print the text entered, call TextPrintManager::print(). The TextPrintManager::view() and TextPrintManager::print_to_file() methods are also available.

The TextPrintManager::page_setup() method can be used as a callback to display a document page setup dialog prior to printing, and this method should only be called in the thread in which the main GTK event loop runs. It is a static method (a TextPrintManager object does not need to have been created before it is called).

Once TextPrintManager::print(), TextPrintManager::view() or TextPrintManager::print_to_file() has been called, the TextPrintManager class owns a reference to itself and so manages its own lifetime - so once one of the methods has been called it doesn't matter if the IntrusivePtr object returned by TextPrintManager::create_manager() goes out of scope (however, once TextPrintManager::print(), TextPrintManager::view() or TextPrintManager::print_to_file() has been called, the object will not be deleted until both printing has completed or failed AND the IntrusivePtr object returned by TextPrintManager::create_manager() has gone out of scope or has been reset()).

Normally, a user would probably only want to use any one TextPrintManager object to print a single print job (it has been designed with that in mind). Nevertheless, if a reference to the object is kept alive via an active IntrusivePtr object, it can be used to print more than one print job. However, if that is done it is not possible to called TextPrintManager::print() TextPrintManager::view(), TextPrintManager::print_to_file() or TextPrintManager::set_text() until the previous print job (if any) has been dispatched to the GTK print system (or cancelled). If the TextPrintManager object is not ready because it is in the middle of handling an earlier print job, then the call to TextPrintManager::print(), TextPrintManager::view(), TextPrintManager::print_to_file() or TextPrintManager::set_text() will return false; if however the new print job was successfully started or text successfully set, they will return true. It is not necessary to check the return value of these methods for the first print job despatched by any one TextPrintManager object.

TextPrintManager::print_to_file() will also return false if no file name to which to print was specified.

This class is not compiled into the library if the library is built with the --without-gtk configuration option.

## Constructor & Destructor Documentation

## TextPrintManager()

Cgu::TextPrintManager::TextPrintManager | ( | const TextPrintManager & |  | ) |

delete

This class cannot be copied: it is intended to be held by IntrusivePtr. The copy constructor is deleted.

## ~TextPrintManager()

Cgu::TextPrintManager::~TextPrintManager | ( |  | ) |

The destructor will not throw. It is thread safe (the TextPrintManager object may be destroyed in any thread), and does not call any GTK/GDK functions.

## Member Function Documentation

## create_manager()

static Cgu::IntrusivePtr<Cgu::TextPrintManager> Cgu::TextPrintManager::create_manager | ( | GtkWindow * | parent = `0`,
|  | const std::string & | font_family = `""`,
|  | int | font_size = `0`
| ) |  |

static

Creates a new TextPrintManager object. No GTK/GDK functions are called by this method, and it is thread safe provided that, if it is called in a thread other than the one in which the GTK event loop runs, Cgu::Notifier::init() has previously been called in the GTK event loop thread.

Parameters

  parent | The parent of the print dialog which will be created by the TextPrintManager object (optional, NULL may be passed).
  font_family | If a particular font is wanted, then this can be entered as the font_family and font_size arguments to this method.. If the default of an empty string for font_family is used, then printing will use the previous font family setting (if any), or if not a font of "Mono". The font passed in this method can in any event be overridden from the "Print font" page in the print dialog.

  font_size

  If a particular font is wanted, then this can be entered as the font_family and font_size arguments to this method.. If the default of 0 for font_size is used, then printing will use the previous font size setting (if any), or if not a size of
  1. The font passed in this method can in any event be overridden from the "Print font" page in the print dialog. If a font size is passed as an argument, then the value must be 0 (default) or between 8 and 24 (actual).

Exceptions

  std::bad_alloc | This method might throw std::bad_alloc if memory is exhausted and the system throws in that case.
  Cgu::Thread::MutexError | This method might throw Cgu::Thread::MutexError if initialisation of the contained mutex fails. (It is often not worth checking for this, as it means either memory is exhausted or pthread has run out of other resources to create new mutexes.)
  Cgu::PipeError | This method might throw Cgu::PipeError if the contained Notifier object is the first Notifier object in the program to be constructed and Cgu::Notifier::init() has not previously been called.

## operator=()

TextPrintManager& Cgu::TextPrintManager::operator= | ( | const TextPrintManager & |  | ) |

delete

This class cannot be copied: it is intended to be held by IntrusivePtr. The assignment operator is deleted.

## page_setup()

static void Cgu::TextPrintManager::page_setup | ( | GtkWindow * | parent = `0` | ) |

static

Runs a page set-up dialog. (If no settings are set using this dialog, then page defaults will be used with a page margin of 15 millimetres.) In a multi-threaded program, this must be called in the thread in which the main GTK event loop runs. If the program by which it is called calls GTK directly in more than one thread and thus employs gdk_threads_enter()/gdk_threads_leave() (rather than, say, Cgu::Notifier or Cgu::Callback::post()), it must also be surrounded by gdk_threads_enter()/gdk_threads_leave() if called otherwise than in a GTK signal handler. (The best approach however is for a program only to address GTK/GDK in the main program thread, for which purpose this library provides various functions and classes for inter-thread communication, such as Cgu::Notifier and Cgu::Callback::post().) It will not throw.

Parameters

  parent | The parent of the page set-up dialog which will be created by the TextPrintManager object (optional, NULL may be passed).

## print()

bool Cgu::TextPrintManager::print | ( |  | ) |

Prints the text set with set_text(). This method is thread-safe and may be called in any thread (it hands off its work to the main program thread via a Cgu::Notifier object), unless the program by which it is called calls GTK directly in more than one thread and thus employs gdk_threads_enter()/gdk_threads_leave() (rather than, say, Cgu::Notifier or Cgu::Callback::post()), in which case it must be called in the main GUI thread only and surrounded by gdk_threads_enter()/gdk_threads_leave() if called otherwise than in a GTK signal handler. (The best approach however is for a program only to address GTK/GDK in the main program thread, for which purpose this library provides various functions and classes for inter-thread communication, such as Cgu::Notifier and Cgu::Callback::post().)

Returns
  Returns true, unless the same TextPrintManager object is being used to print more than one print job and when this method is called it is already printing another print job (in which case it returns false).

Exceptions

  std::bad_alloc | This method might throw std::bad_alloc if memory is exhausted and the system throws in that case, but only if it is called in the main program thread. Otherwise it will not throw.

## print_to_file()

bool Cgu::TextPrintManager::print_to_file | ( | const char * | filename | ) |

Prints the text set with set_text() to file. This method is thread-safe and may be called in any thread (it hands off its work to the main program thread via a Cgu::Notifier object), unless the program by which it is called calls GTK directly in more than one thread and thus employs gdk_threads_enter()/gdk_threads_leave() (rather than, say, Cgu::Notifier or Cgu::Callback::post()), in which case it must be called in the main GUI thread only and surrounded by gdk_threads_enter()/gdk_threads_leave() if called otherwise than in a GTK signal handler. (The best approach however is for a program only to address GTK/GDK in the main program thread, for which purpose this library provides various functions and classes for inter-thread communication, such as Cgu::Notifier and Cgu::Callback::post().)

Parameters

  filename | The filename of the file to which the text is to be printed.

Returns
  Returns true, unless the same TextPrintManager object is being used to print more than one print job and when this method is called it is already printing another print job, or no filename to print was specified (in either of which case it returns false).

Exceptions

  std::bad_alloc | This method might throw std::bad_alloc if memory is exhausted and the system throws in that case.

## set_text()

bool Cgu::TextPrintManager::set_text | ( | std::unique_ptr< std::string > & | text | ) |

Sets the text to be printed. This method is thread-safe and may be called in any thread. No GTK/GDK functions are called. It will not throw.

Parameters

  text | The text to be printed. It must be in valid UTF-8 format. Ownership is taken of the text string (a move operation is carried out) unless false is returned.

Returns
  Returns true, unless the same TextPrintManager object is being used to print more than one print job and when this method is called it is already printing another print job (in which case it returns false). If it returns false, ownership is not taken of the text string (it can be reused).

## view()

bool Cgu::TextPrintManager::view | ( |  | ) |

Provides a print pre-view of the text set with set_text(). This method is thread-safe and may be called in any thread (it hands off its work to the main program thread via a Cgu::Notifier object), unless the program by which it is called calls GTK directly in more than one thread and thus employs gdk_threads_enter()/gdk_threads_leave() (rather than, say, Cgu::Notifier or Cgu::Callback::post()), in which case it must be called in the main GUI thread only and surrounded by gdk_threads_enter()/gdk_threads_leave() if called otherwise than in a GTK signal handler. (The best approach however is for a program only to address GTK/GDK in the main program thread, for which purpose this library provides various functions and classes for inter-thread communication, such as Cgu::Notifier and Cgu::Callback::post().)

Returns
  Returns true, unless the same TextPrintManager object is being used to print more than one print job and when this method is called it is already printing another print job (in which case it returns false).

Exceptions

  std::bad_alloc | This method might throw std::bad_alloc if memory is exhausted and the system throws in that case, but only if it is called in the main program thread. Otherwise it will not throw.

The documentation for this class was generated from the following file:

- text_print_manager.h