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<div class="chapter">
<div class="titlepage"><div><div><h1 class="title">
<a name="chapter-printing"></a>Chapter 21. Printing</h1></div></div></div>
<div class="toc">
<p><b>Table of Contents</b></p>
<ul class="toc">
<li><span class="section"><a href="chapter-printing.html#sec-printoperation">PrintOperation</a></span></li>
<li><span class="section"><a href="sec-page-setup.html">Page setup</a></span></li>
<li><span class="section"><a href="sec-printing-rendering-text.html">Rendering text</a></span></li>
<li><span class="section"><a href="sec-async-printing-ops.html">Asynchronous operations</a></span></li>
<li><span class="section"><a href="sec-printing-export-to-pdf.html">Export to PDF</a></span></li>
<li><span class="section"><a href="sec-extending-print-dialog.html">Extending the print dialog</a></span></li>
<li><span class="section"><a href="sec-printing-preview.html">Preview</a></span></li>
<li><span class="section"><a href="sec-printing-printdialog.html">PrintDialog</a></span></li>
<li><span class="section"><a href="sec-printing-examples.html">Examples</a></span></li>
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<p>
At the application development level, <span class="application">gtkmm</span>'s printing API
provides dialogs that are consistent across applications and allows use of Cairo's common drawing API, with Pango-driven text rendering. In the implementation of this common API, platform-specific backends and printer-specific drivers are used.
</p>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-printoperation"></a>PrintOperation</h2></div></div></div>
<p>
The primary object is <code class="classname">Gtk::PrintOperation</code>, allocated
for each print operation. To handle page drawing connect to its signals,
or inherit from it and override the default virtual signal handlers.
<code class="classname">PrintOperation</code> automatically handles all the settings
affecting the print loop.
</p>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-printoperation-signals"></a>Signals</h3></div></div></div>
<p>
The <code class="methodname">PrintOperation::run()</code> method starts the print loop,
during which various signals are emitted:
</p>
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<li class="listitem">
<p>
<code class="literal">begin_print</code>:
You must handle this signal, because this is where you
create and set up a <code class="classname">Pango::Layout</code> using the
provided <code class="classname">Gtk::PrintContext</code>, and break up your
printing output into pages.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">paginate</code>: Pagination is potentially slow so if you
need to monitor it you can call the
<code class="methodname">PrintOperation::set_show_progress()</code> method and
handle this signal.
</p>
</li>
<li class="listitem">
<p>
For each page that needs to be rendered, the following signals
are emitted:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<code class="literal">request_page_setup</code>: Provides a
<code class="classname">PrintContext</code>, page number and
<code class="classname">Gtk::PageSetup</code>. Handle this signal if you
need to modify page setup on a per-page basis.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">draw_page</code>: You must handle this signal, which provides a
<code class="classname">PrintContext</code> and a page number.
The <code class="classname">PrintContext</code> should be used
to create a <code class="classname">Cairo::Context</code> into which
the provided page should be drawn. To render text, iterate over
the <code class="classname">Pango::Layout</code> you created in the
<code class="literal">begin_print</code> handler.
</p>
</li>
</ul></div>
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</p>
</li>
<li class="listitem">
<p>
<code class="literal">end_print</code>: A handler for it is a safe place to free
any resources related to a <code class="classname">PrintOperation</code>.
If you have your custom class that inherits from
<code class="classname">PrintOperation</code>, it is naturally simpler to do it
in the destructor.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">done</code>: This signal is emitted when printing is finished, meaning when the
print data is spooled. Note that the provided
<code class="literal">Gtk::PrintOperation::Result</code> may indicate that
an error occurred. In any case you probably want to notify the user
about the final status.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">status_changed</code>: Emitted whenever a print job's
status changes, until it is finished. Call the
<code class="methodname">PrintOperation::set_track_print_status()</code> method to
monitor the job status after spooling. To see the status, use
<code class="methodname">get_status()</code> or
<code class="methodname">get_status_string()</code>.
</p>
</li>
</ul></div>
<p>
</p>
<p>
<a class="ulink" href="https://gnome.pages.gitlab.gnome.org/gtkmm/classGtk_1_1PrintOperation.html" target="_top">Reference</a>
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