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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>13.7. A TextView Example</title><meta name="generator" content="DocBook XSL Stylesheets V1.65.1"><link rel="home" href="index.html" title="PyGTK 2.0 Tutorial"><link rel="up" href="ch-TextViewWidget.html" title="Chapter 13. TextView Widget"><link rel="previous" href="sec-TextTagsAndTextTagTables.html" title="13.6. Text Tags and Tag Tables"><link rel="next" href="ch-TreeViewWidget.html" title="Chapter 14. Tree View Widget"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">13.7. A TextView Example</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="sec-TextTagsAndTextTagTables.html">Prev</a> </td><th width="60%" align="center">Chapter 13. TextView Widget</th><td width="20%" align="right"> <a accesskey="n" href="ch-TreeViewWidget.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sec-TextViewExample"></a>13.7. A TextView Example</h2></div></div><div></div></div><p>The <a href="examples/testtext.py" target="_top"><span><b class="command">testtext.py</b></span></a> example
program (derived from the <tt class="filename">testtext.c</tt> program included
in the GTK+ 2.0.x distribution) demonstrates the use of the
<tt class="classname">TextView</tt> widget and its associated objects:
<tt class="classname">TextBuffer</tt>s, <tt class="classname">TextIter</tt>s,
<tt class="classname">TextMark</tt>s, <tt class="classname">TextTag</tt>s,
<tt class="classname">TextTagTable</tt>s. <a href="sec-TextViewExample.html#testtextfig" title="Figure 13.2. TextView Example">Figure 13.2, “TextView Example”</a>
illustrates its operation:</p><div class="figure"><a name="testtextfig"></a><p class="title"><b>Figure 13.2. TextView Example</b></p><div class="mediaobject" align="center"><img src="figures/testtext.png" align="middle" alt="TextView Example"></div></div><p>The <a href="examples/testtext.py" target="_top"><span><b class="command">testtext.py</b></span></a> program
defines a number of classes in addition to the application class
<tt class="classname">TestText</tt>:</p><div class="itemizedlist"><ul type="disc"><li><p><tt class="classname">Buffer</tt> class, lines 99-496, is
subclassed from the <tt class="classname">gtk.TextBuffer</tt> type. It provides
the editing buffer capabilities used by the <tt class="classname">View</tt>
objects.</p></li><li><p><tt class="classname">View</tt> class, lines 498-1126, is
subclassed from the <tt class="classname">gtk.Window</tt> type and wraps a
<tt class="classname">gtk.TextView</tt> object that uses a
<tt class="classname">Buffer</tt> object instead of a
<tt class="classname">gtk.TextBuffer</tt> object. It provides a window and the
visual display of the contents of a <tt class="classname">Buffer</tt> object as
well as a menubar.</p></li><li><p><tt class="classname">FileSel</tt> class, lines 73-97, is
subclassed from the <tt class="classname">gtk.FileSelection</tt> type to provide
selection of filenames for the <tt class="classname">Buffer</tt>
contents.</p></li><li><p><tt class="classname">Stack</tt> class to provide simple stack
objects.</p></li></ul></div><p>The color cycle display is implemented by using text tags applied
to a section of text in a buffer. Lines 109-115 (in the
<tt class="methodname">__init__</tt>() method) create these tags and lines
763-784 (<tt class="methodname">do_apply_colors</tt>() method) apply the color
tags to a section of text two characters at a time. Lines 202-239 provide
the methods (<tt class="methodname">color_cycle_timeout</tt>(),
<tt class="methodname">set_colors</tt>() and
<tt class="methodname">cycle_colors</tt>()) that produce the color cycle
display when enabled. Color cycling is enabled by setting (line 220) the
<i class="parameter"><tt>foreground_gdk</tt></i> property of the individual
<i class="parameter"><tt>color_tags</tt></i> (which also sets the
<i class="parameter"><tt>foreground_set</tt></i> property). Color cycling is disabled
by setting the <i class="parameter"><tt>foreground_set</tt></i> property to
<tt class="literal">FALSE</tt> (line 222). The colors are periodically changed by
shifting the <i class="parameter"><tt>start_hue</tt></i> (line 237)</p><p>A new <tt class="classname">Buffer</tt> is filled with example content
when the
<span class="guimenu">Test</span>-><span class="guimenuitem">Example</span>
menu item is selected (the <tt class="methodname">fill_example_buffer</tt>()
method in lines 302-372). The example buffer contains text of various
colors, styles and languages and pixbufs. The
<tt class="methodname">init_tags</tt>() method (lines 260-300) sets up a
variety of <tt class="classname">TextTag</tt>s for use with the example text.
The event signal of these tags is connected to the
<tt class="methodname">tag_event_handler</tt>() method (lines 241-256) to
illustrate button and motion event capture.</p><p>The <tt class="classname">TextView</tt> wrap mode is set to WRAP_WORD
(line 580) and the <tt class="classname">TextView</tt> border windows are
displayed by setting their sizes in lines 587-588 and line 596-597. The left
and right border windows are used to display line numbers and the top and
bottom border windows display the tab locations when custom tabs are
set. The border windows are updated when an "expose-event" signal is
received by the <tt class="classname">TextView</tt> (lines 590 and 599). The
<tt class="methodname">line_numbers_expose</tt>() method (lines 1079-1116)
determines whether the left or right border window has an expose event and
if so calculates the size of the expose area. Then the location of the line
start and the line number for each line in the exposed area is calculated in
the <tt class="methodname">get_lines</tt>() method (lines 1057-1077). The line
numbers are then drawn in the border window at the location (transformed by
line 1109).</p><p>The custom tab locations are displayed in the top and bottom
border windows in a similar fashion (lines 1013-1055). They are displayed
only when the cursor is moved inside a range of text that has the custom tab
attribute set. This is detected by handling the "mark-set" signal in the
<tt class="methodname">cursor_set_handler</tt>() method (lines 999-1011) and
invalidating the top and bottom border windows if the mark set is the
<i class="parameter"><tt>insert</tt></i> mark.</p><p>Movable widgets are added to a <tt class="classname">View</tt> with
the <tt class="methodname">do_add_children</tt>() method (lines 892-899) which
calls the <tt class="methodname">add_movable_children</tt>() method (lines
874-890). The children are <tt class="classname">gtk.Label</tt>s that can be
dragged around inside the various windows that are part of a
<tt class="classname">TextView</tt> widget.</p><p>Likewise, widgets are added to the <tt class="classname">TextView</tt>
windows of a <tt class="classname">View</tt> and the
<tt class="classname">Buffer</tt> by using the
<tt class="methodname">do_add_focus_children</tt>() method (lines
901-949).</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sec-TextTagsAndTextTagTables.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch-TextViewWidget.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch-TreeViewWidget.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">13.6. Text Tags and Tag Tables </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 14. Tree View Widget</td></tr></table></div></body></html>
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