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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>The Be Book - System Overview - The Interface Kit</title><link rel="stylesheet" href="be_book.css" type="text/css" media="all" /><link rel="shortcut icon" type="image/vnd.microsoft.icon" href="./images/favicon.ico" /><!--[if IE]>
<link rel="stylesheet" type="text/css" href="be_book_ie.css" />
<![endif]--><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><meta name="keywords" content="Access, BeOS, BeBook, API" /><link rel="start" href="index.html" title="The Be Book" /><link rel="up" href="TheInterfaceKit_Overview.html" title="The Interface Kit" /><link rel="prev" href="BTextControl_Overview.html" title="BTextControl" /><link rel="next" href="BView_Overview.html" title="BView" /></head><body><div id="header"><div id="headerT"><div id="headerTL"><a accesskey="p" href="BTextControl_Overview.html" title="BTextControl"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a accesskey="u" href="TheInterfaceKit_Overview.html" title="The Interface Kit"><img src="./images/navigation/up.png" alt="Up" /></a> <a accesskey="n" href="BView_Overview.html" title="BView"><img src="./images/navigation/next.png" alt="Next" /></a></div><div id="headerTR"><div id="navigpeople"><a href="http://www.haiku-os.org"><img src="./images/People_24.png" alt="haiku-os.org" title="Visit The Haiku Website" /></a></div><div class="navighome" title="Home"><a accesskey="h" href="index.html"><img src="./images/navigation/home.png" alt="Home" /></a></div><div class="navigboxed" id="navigindex"><a accesskey="i" href="ClassIndex.html" title="Index">I</a></div><div class="navigboxed" id="naviglang" title="English">en</div></div><div id="headerTC">The Be Book - System Overview - The Interface Kit</div></div><div id="headerB">Prev: <a href="BTextControl_Overview.html">BTextControl</a>  Up: <a href="TheInterfaceKit_Overview.html">The Interface Kit</a>  Next: <a href="BView_Overview.html">BView</a></div><hr /></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h2 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BTextView_Overview"></a>BTextView</h2></div></div></div><a id="id559742" class="indexterm"></a><p>
A <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
object displays text on-screen, and provides these text
manipulating features:
</p><ul class="itemizedlist"><li><p>
It lets the user enter, select, and edit text from the keyboard and
mouse.
</p></li><li><p>
It supports standard Cut, Copy, Paste, Delete, and Select All editing
commands
</p></li><li><p>
It provides an Undo mechanism.
</p></li></ul><p>
By default, a <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
displays all its text in a single font and color. The
<a class="link" href="BTextView.html#BTextView_SetStylable" title="SetStylable(), IsStylable()"><code class="methodname">SetStylable()</code></a>
turns on support for multiple character formats.
</p><p>
Paragraph formats—such as alignment and tab widths—are
uniform for all text the BTextView displays. These properties can be set,
but the setting always applies to the entire text.
</p><div class="admonition warning"><div class="title">Warning</div><div class="graphic"><img class="icon" alt="Warning" width="32" src="./images/admonitions/Stop_32.png" /><div class="text"><p>The <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
class isn't multi-thread safe; don't issue
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
calls on a <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
object from multiple threads, or you may see unusual
behavior; in general, only the thread that created the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
should issue calls on it.</p></div></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BTextView_Overview_Offsets"></a>Offsets</h3></div></div></div><p>
The <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
locates particular characters in its text buffer by offsets
from the beginning of the data. The offsets count bytes, not characters,
and begin at 0. A single character is identified by the offset of the
first byte of the character. A group of characters—the current
selection, for example—is delimited by the offsets that bound its
first and last characters; all characters beginning with the first offset
up to, but not including, the last offset are part of the group.
</p><p>
For example, suppose the <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
contains the following text in Unicode UTF-8 encoding,
</p><pre class="screen">
The BeOS(TM) is . . .
</pre><p>
and "BeOS(TM)" is selected.
<a class="link" href="BTextView.html#BTextView_GetSelection" title="GetSelection()"><code class="methodname">GetSelection()</code></a>
would return 4 and 11 as the offsets that enclose the selection. The
character 'B' occupies the fourth byte of text and the space following the
trademark symbol is the eleventh byte of text. The characters in
"BeOS" are each encoded in one byte, but '(TM) ' takes up three
bytes in UTF-8. Thus the five-character selection occupies 7 bytes (and
offsets) of text.
</p><p>
Although offsets count bytes, they can also be thought of as designating
positions between characters. The position at the beginning of the text
is offset 0, the position between the space and the 'B' in the example
above is at offset 4, the position between the '(TM) ' and the space is
at offset 11, and so on. Thus, even if no characters are selected, the
insertion point (and location of the caret) can still be designated by an
offset.
</p><p>
Most <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
functions expect the offsets they're passed to mark
positions between characters; the results are not defined if a
character-internal offset is specified instead.
</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="id559941"></a>Graphics Primitives</h3></div></div></div><p>
The <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>'s
mechanism for formatting and drawing text uses the
graphics primitives it inherits from the
<a class="link" href="BView.html" title="BView">"<code class="classname">BView</code></a> class. However, it largely
presents its own API for determining the appearance of the text it draws.
You should not attempt to affect the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
by calling primitive
<a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>
functions like
<a class="link" href="BView.html#BView_MovePenTo"><code class="methodname">MovePenTo()</code></a>,
<a class="link" href="BView.html#BView_SetFont" title="SetFont(), GetFont()"><code class="methodname">SetFont()</code></a>, or
<a class="link" href="BView.html#BView_SetHighColor" title="SetHighColor(), HighColor() , SetLowColor() , LowColor()"><code class="methodname">SetHighColor()</code></a>. Instead, use
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
functions like
<a class="link" href="BTextView.html#BTextView_SetFontAndColor" title="SetFontAndColor(), GetFontAndColor()"><code class="methodname">SetFontAndColor()</code></a>
and let the object take care of formatting and drawing the text.
</p><p>
The one inherited function that can influence the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a> is
<a class="link" href="BView.html#BView_SetViewColor" title="SetViewColor(), ViewColor()"><code class="methodname">SetViewColor()</code></a>.
This function determines the background against which the
text is drawn and the color that is used in antialiasing calculations.
</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="id560044"></a>Resizing</h3></div></div></div><p>
A <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
can be made to resize itself to exactly fit the text that the
user enters. This is sometimes appropriate for small one-line text
fields. See the
<a class="link" href="BTextView.html#BTextView_MakeResizable" title="MakeResizable(), IsResizable()"><code class="methodname">MakeResizable()</code></a> function.
</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="id560071"></a>BTextView and BScrollBars</h3></div></div></div><p>
If you add scrollbars to control the position of the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>'s
document—this includes using a <a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a> as the target of a
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>BScrollView—the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
will update the scrollbars for you. (Note that it doesn't own the
scrollbars; you still have to delete them yourself if you created them.)
When the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
is first displayed and thereafter resized, the scrollbars' ranges, step
sizes, and scroller positions and proportions are automatically reset to
reflect the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
object's bounds. Attempts to set these parameters directly (through
<a class="link" href="BScrollBar.html#BScrollBar_SetRange" title="SetRange(), GetRange()"><code class="methodname">BScrollBar::SetRange()</code></a>
etc.), are worse than ignored; they're actually applied, and then (at some point) the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
will notice the change in the scrollbars and reset them. Looks like flicker to me.
</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><hr /><div xmlns:d="http://docbook.org/ns/docbook"><h3 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BTextView_Overview_ShortcutsAndMenuItems"></a>Shortcuts and Menu Items</h3></div></div></div><p>
When it's the focus view for its window, a
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
automatically responds to a set of keyboard shortcuts:
</p><ul class="itemizedlist"><li><p>
<span class="keycap">Command</span>+<span class="keycap">x</span>
cuts text and copies it to the clipboard
</p></li><li><p>
<span class="keycap">Command</span>+<span class="keycap">c</span>
copies text to the clipboard without cutting it
</p></li><li><p>
<span class="keycap">Command</span>+<span class="keycap">v</span>
pastes text taken from the clipboard
</p></li><li><p>
<span class="keycap">Command</span>+<span class="keycap">a</span>
selects all of the text in the
<a class="link" href="BTextView.html" title="BTextView"><code class="classname">BTextView</code></a>
</p></li><li><p>
<span class="keycap">Command</span>+<span class="keycap">z</span>
undoes the previous action
</p></li></ul><p>
If you create menu items for these actions, you have to assign the
<a class="link" href="BMenuItem.html" title="BMenuItem"><code class="classname">BMenuItem</code></a>
shortcuts and command constants yourself:
</p><div class="informaltable"><table border="1"><colgroup><col /><col /></colgroup><thead><tr><th>Action</th><th>Constant</th><th>Shortcut</th></tr></thead><tbody><tr><td>Select all</td><td><code class="constant">B_SELECT_ALL</code></td><td><span class="keycap">Command</span>+<span class="keycap">a</span></td></tr><tr><td>Cut</td><td><code class="constant">B_CUT</code></td><td><span class="keycap">Command</span>+<span class="keycap">x</span></td></tr><tr><td>Copy</td><td><code class="constant">B_COPY</code></td><td><span class="keycap">Command</span>+<span class="keycap">c</span></td></tr><tr><td>Paste</td><td><code class="constant">B_PASTE</code></td><td><span class="keycap">Command</span>+<span class="keycap">v</span></td></tr><tr><td>Undo</td><td><code class="constant">B_UNDO</code></td><td><span class="keycap">Command</span>+<span class="keycap">z</span></td></tr></tbody></table></div></div></div><div id="footer"><hr /><div id="footerT">Prev: <a href="BTextControl_Overview.html">BTextControl</a>  Up: <a href="TheInterfaceKit_Overview.html">The Interface Kit</a>  Next: <a href="BView_Overview.html">BView</a> </div><div id="footerB"><div id="footerBL"><a href="BTextControl_Overview.html" title="BTextControl"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a href="TheInterfaceKit_Overview.html" title="The Interface Kit"><img src="./images/navigation/up.png" alt="Up" /></a> <a href="BView_Overview.html" title="BView"><img src="./images/navigation/next.png" alt="Next" /></a></div><div id="footerBR"><div><a href="http://www.haiku-os.org"><img src="./images/People_24.png" alt="haiku-os.org" title="Visit The Haiku Website" /></a></div><div class="navighome" title="Home"><a accesskey="h" href="index.html"><img src="./images/navigation/home.png" alt="Home" /></a></div></div><div id="footerBC"><a href="http://www.access-company.com/home.html" title="ACCESS Co."><img alt="Access Company" src="./images/access_logo.png" /></a></div></div></div><div id="licenseFooter"><div id="licenseFooterBL"><a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/" title="Creative Commons License"><img alt="Creative Commons License" style="border-width:0" src="https://licensebuttons.net/l/by-nc-nd/3.0/88x31.png" /></a></div><div id="licenseFooterBR"><a href="./LegalNotice.html">Legal Notice</a></div><div id="licenseFooterBC"><span id="licenseText">This work is licensed under a
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