256 lines
32 KiB
HTML
256 lines
32 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>The Be Book - Classes And Methods - 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]>
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<link rel="stylesheet" type="text/css" href="be_book_ie.css" />
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<![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.html" title="The Interface Kit" /><link rel="prev" href="BScreen.html" title="BScreen" /><link rel="next" href="BScrollView.html" title="BScrollView" /></head><body><div id="header"><div id="headerT"><div id="headerTL"><a accesskey="p" href="BScreen.html" title="BScreen"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a accesskey="u" href="TheInterfaceKit.html" title="The Interface Kit"><img src="./images/navigation/up.png" alt="Up" /></a> <a accesskey="n" href="BScrollView.html" title="BScrollView"><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 - Classes And Methods - The Interface Kit</div></div><div id="headerB">Prev: <a href="BScreen.html">BScreen</a> Up: <a href="TheInterfaceKit.html">The Interface Kit</a> Next: <a href="BScrollView.html">BScrollView</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="BScrollBar"></a>BScrollBar</h2></div></div></div><a id="id1023900" class="indexterm"></a><div class="classheader"><table border="0"><colgroup><col /><col /></colgroup><tbody><tr><td><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody><tr><td>Derived From:</td><td><a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a></td></tr><tr><td>Mix-in Classes:</td><td>–</td></tr><tr><td>Declared In:</td><td><code class="filename">interface/ScrollBar.h</code></td></tr><tr><td>Library:</td><td><code class="filename">libbe.so</code></td></tr><tr><td>Allocation:</td><td>Constructor or on the stack</td></tr></tbody></table></td><td>
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<a class="link overview" href="BScrollBar_Overview.html" title="BScrollBar">Class Overview</a>
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<div class="toc"><ul><li><span class="section"><a href="BScrollBar.html#BScrollBar_ConstructorDestructor">Constructor and Destructor</a></span></li><li><span class="section"><a href="BScrollBar.html#BScrollBar_HookFunctions">Hook Functions</a></span></li><li><span class="section"><a href="BScrollBar.html#BScrollBar_MemberFunctions">Member Functions</a></span></li><li><span class="section"><a href="BScrollBar.html#BScrollBar_StaticFunctions">Static Functions</a></span></li><li><span class="section"><a href="BScrollBar.html#BScrollBar_ArchivedFields">Archived Fields</a></span></li></ul></div>
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</td></tr></tbody></table></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="BScrollBar_ConstructorDestructor"></a>Constructor and Destructor</h3></div></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_Constructor"></a>BScrollBar()</h4></div></div></div><div class="synopsisgroup">
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<code class="constructorsynopsis cpp"><span class="methodname">BScrollBar</span>(<span class="methodparam"><span class="type"><a class="link" href="BRect.html" title="BRect"><code class="classname">BRect</code></a> </span><span class="parameter">frame</span></span>,<br /> <span class="methodparam"><span class="modifier">const </span><span class="type">char* </span><span class="parameter">name</span></span>,<br /> <span class="methodparam"><span class="type"><a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>* </span><span class="parameter">target</span></span>,<br /> <span class="methodparam"><span class="type">float </span><span class="parameter">min</span></span>,<br /> <span class="methodparam"><span class="type">float </span><span class="parameter">max</span></span>,<br /> <span class="methodparam"><span class="type">orientation </span><span class="parameter">posture</span></span>);</code>
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<code class="constructorsynopsis cpp"><span class="methodname">BScrollBar</span>(<span class="methodparam"><span class="type"><a class="link" href="BMessage.html" title="BMessage"><code class="classname">BMessage</code></a>* </span><span class="parameter">archive</span></span>);</code>
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</div><p>
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Initializes the <code class="classname">BScrollBar</code> and connects it to the target view that it
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will scroll. It will be a horizontal scroll bar if posture is
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<code class="constant">B_HORIZONTAL</code> and a vertical scroll bar if posture is
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<code class="constant">B_VERTICAL</code>.
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</p><p>
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The range of values that the scroll bar can represent at the outset is
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set by <code class="parameter">min</code> and <code class="parameter">max</code>.
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These values should be calculated from the boundaries
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of a rectangle that encloses the entire contents of the target
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view—everything that it can draw. If <code class="parameter">min</code>
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and <code class="parameter">max</code> are both 0, the
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scroll bar is disabled and the knob is not drawn.
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</p><p>
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The object's initial value is 0 even if that falls outside the range set
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for the scroll bar.
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</p><p>
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The other arguments, <code class="parameter">frame</code> and <code class="parameter">name</code>,
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are the same as for other
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<a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>s:
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</p><ul class="itemizedlist"><li><p>
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The <code class="parameter">frame</code> rectangle locates the scroll bar within its parent view.
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For consistency in the user interface, a horizontal scroll bar should
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be <code class="constant">B_H_SCROLL_BAR_HEIGHT</code> coordinate units high, and a vertical scroll
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bar should be <code class="constant">B_V_SCROLL_BAR_WIDTH</code> units wide.
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</p></li><li><p>
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The <code class="classname">BScrollBar</code>'s <code class="parameter">name</code> identifies it and permits it to be located by
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the <a class="link" href="BView.html#BView_FindView" title="FindView()"><code class="methodname">FindView()</code></a> function. It can be <code class="constant">NULL</code>.
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</p></li></ul><p>
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Unlike other <a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>s,
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the <code class="classname">BScrollBar</code> constructor doesn't set an automatic
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resizing mode. By default, scroll bars have the resizing behavior that
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befits their posture—horizontal scroll bars resize themselves
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horizontally (as if they had a resizing mode that combined
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<code class="constant">B_FOLLOW_LEFT_RIGHT</code> with <code class="constant">B_FOLLOW_BOTTOM</code>)
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and vertical scroll bars resize
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themselves vertically (as if their resizing mode combined
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<code class="constant">B_FOLLOW_TOP_BOTTOM</code> with <code class="constant">B_FOLLOW_RIGHT</code>).
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_Destructor"></a>~BScrollBar()</h4></div></div></div><code class="destructorsynopsis cpp"><span class="modifier">virtual </span><span class="methodname">~BScrollBar</span>();</code><p>
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Disconnects the scroll bar from its target.
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</p></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="BScrollBar_HookFunctions"></a>Hook Functions</h3></div></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_AttachedToWindow"></a>AttachedToWindow()</h4></div></div></div><code class="methodsynopsis cpp"><span class="modifier">virtual </span><span class="void">void </span><span class="methodname">AttachedToWindow</span>();</code><p>
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Makes sure that the <span class="application">Application Server</span> is
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cognizant of the <code class="classname">BScrollBar</code>'s
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value, if a value was set before the object was attached to a window.
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</p><p>
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See also:
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<a class="link" href="BView.html#BView_AttachedToWindow" title="AttachedToWindow(), AllAttached()"><code class="methodname">BView::AttachedToWindow()</code></a>
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_ValueChanged"></a>ValueChanged()</h4></div></div></div><code class="methodsynopsis cpp"><span class="modifier">virtual </span><span class="void">void </span><span class="methodname">ValueChanged</span>(<span class="methodparam"><span class="type">float </span><span class="parameter">newValue</span></span>);</code><p>
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Responds to a notification that the value of the scroll bar has changed
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to <code class="parameter">newValue</code>. For a horizontal scroll bar, this function interprets
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<code class="parameter">newValue</code> as the coordinate value that should be at the left side of the
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target view's bounds rectangle. For a vertical scroll bar, it interprets
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<code class="parameter">newValue</code> as the coordinate value that should be at the top of the
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rectangle. It calls
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<a class="link" href="BView.html#BView_ScrollTo"><code class="methodname">ScrollTo()</code></a>
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to scroll the target's contents into
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position, unless they have already been scrolled.
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</p><p>
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<code class="methodname">ValueChanged()</code> is called as the result both of user actions
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(<code class="constant">B_VALUE_CHANGED</code> messages received from the
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<span class="application">Application Server</span>) and of
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programmatic ones. Programmatically, scrolling can be initiated by the
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target view (calling <a class="link" href="BView.html#BView_ScrollTo"><code class="methodname">ScrollTo()</code></a>)
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or by the <code class="classname">BScrollBar</code> (calling
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<a class="link" href="BScrollBar.html#BScrollBar_SetValue" title="SetValue(), Value()"><code class="methodname">SetValue()</code></a>
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or <a class="link" href="BScrollBar.html#BScrollBar_SetRange" title="SetRange(), GetRange()"><code class="methodname">SetRange()</code></a>).
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</p><p>
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In all these cases, the target view and the scroll bars need to be kept
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in synch. This is done by a chain of function calls:
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<code class="methodname">ValueChanged()</code> calls
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<a class="link" href="BView.html#BView_ScrollTo"><code class="methodname">ScrollTo()</code></a>,
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which in turn calls <a class="link" href="BScrollBar.html#BScrollBar_SetValue" title="SetValue(), Value()"><code class="methodname">SetValue()</code></a>,
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which then calls
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<code class="methodname">ValueChanged()</code> again. It's up to <code class="methodname">ValueChanged()</code> to get off this
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merry-go-round, which it does by checking the target view's bounds
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rectangle. If <code class="parameter">newValue</code> already matches the left or top side of the bounds
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rectangle, if forgoes calling
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<a class="link" href="BView.html#BView_ScrollTo"><code class="methodname">ScrollTo()</code></a>.
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</p><p>
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<code class="methodname">ValueChanged()</code> does nothing if a target
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<a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a> hasn't been set—or if
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the target has been set by name, but the name doesn't correspond to an
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actual <a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a> within the scroll bar's window.
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</p><p>
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Derived classes can override this function to interpret <code class="parameter">newValue</code>
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differently, or to do something in addition to scrolling the target view.
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</p><p>
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See also:
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<a class="link" href="BScrollBar.html#BScrollBar_SetTarget" title="SetTarget(), Target()"><code class="methodname">SetTarget()</code></a>,
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<a class="link" href="BScrollBar.html#BScrollBar_SetValue" title="SetValue(), Value()"><code class="methodname">SetValue()</code></a>,
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<a class="link" href="BView.html#BView_ScrollTo"><code class="methodname">BView::ScrollTo()</code></a>
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</p></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="BScrollBar_MemberFunctions"></a>Member Functions</h3></div></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_Archive"></a>Archive()</h4></div></div></div><code class="methodsynopsis cpp"><span class="modifier">virtual </span><span class="type">status_t </span><span class="methodname">Archive</span>(<span class="methodparam"><span class="type"><a class="link" href="BMessage.html" title="BMessage"><code class="classname">BMessage</code></a>* </span><span class="parameter">archive</span></span>,<br /> <span class="methodparam"><span class="type">bool </span><span class="parameter">deep</span><span class="initializer"> = <span class="constant">true</span></span></span>) <span class="modifier">const</span>;</code><p>
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Calls the inherited version of
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<a class="link" href="BView.html#BView_Archive" title="Archive()"><code class="methodname">Archive()</code></a>,
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then adds the <code class="classname">BScrollBar</code>'s
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range, orientation, current value and proportion, and the size of its big
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and little steps to the
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<a class="link" href="BMessage.html" title="BMessage"><code class="classname">BMessage</code></a> <code class="parameter">archive</code>.
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</p><p>
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See also:
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<a class="link" href="BArchivable.html#BArchivable_Archive" title="Archive()"><code class="methodname">BArchivable::Archive()</code></a>,
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<a class="link" href="BScrollBar.html#BScrollBar_Instantiate" title="Instantiate()"><code class="methodname">Instantiate()</code></a> static function
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_Orientation"></a>Orientation()</h4></div></div></div><code class="methodsynopsis cpp"><span class="type">orientation </span><span class="methodname">Orientation</span>() <span class="modifier">const</span>;</code><p>
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Returns <code class="constant">B_HORIZONTAL</code> if the object represents a horizontal scroll bar and
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<code class="constant">B_VERTICAL</code> if it represents a vertical scroll bar.
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</p><p>
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See also:
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The <code class="classname">BScrollBar</code>
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<a class="link" href="BScrollBar.html#BScrollBar_Constructor" title="BScrollBar()"><code class="methodname">constructor</code></a>
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_SetProportion"></a><a id="BScrollBar_Proportion"></a>
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SetProportion(), Proportion()</h4></div></div></div><code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">SetProportion</span>(<span class="methodparam"><span class="type">float </span><span class="parameter">ratio</span></span>);</code><code class="methodsynopsis cpp"><span class="type">float </span><span class="methodname">Proportion</span>() <span class="modifier">const</span>;</code><p>
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These functions set and return a value between 0.0 and 1.0 that
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represents the proportion of the entire document that can be displayed
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within the target view—the ratio of the width (or height) of the
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target's bounds rectangle to the width (or height) of its data rectangle.
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This ratio determines the size of a proportional scroll knob relative to
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the whole scroll bar. It's not adjusted to take into account the minimum
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size of the knob.
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</p><p>
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The proportion should be reset as the size of the data rectangle changes
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(as data is entered and removed from the document) and when the target
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view is resized.
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_SetRange"></a><a id="BScrollBar_GetRange"></a>
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SetRange(), GetRange()</h4></div></div></div><code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">SetRange</span>(<span class="methodparam"><span class="type">float </span><span class="parameter">min</span></span>,<br /> <span class="methodparam"><span class="type">float </span><span class="parameter">max</span></span>);</code><code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">GetRange</span>(<span class="methodparam"><span class="type">float* </span><span class="parameter">min</span></span>,<br /> <span class="methodparam"><span class="type">float* </span><span class="parameter">max</span></span>) <span class="modifier">const</span>;</code><p>
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These functions modify and return the range of the scroll bar.
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<code class="methodname">SetRange()</code>
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sets the minimum and maximum values of the scroll bar to <code class="parameter">min</code> and <code class="parameter">max</code>.
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<code class="methodname">GetRange()</code> places the current minimum and maximum in the variables that
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<code class="parameter">min</code> and <code class="parameter">max</code> refer to.
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</p><p>
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If the scroll bar's current value falls outside the new range, it will be
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reset to the closest value—either <code class="parameter">min</code> or <code class="parameter">max</code>—within range.
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<a class="link" href="BScrollBar.html#BScrollBar_ValueChanged" title="ValueChanged()"><code class="methodname">ValueChanged()</code></a>
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is called to inform the <code class="classname">BScrollBar</code> of the change whether
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or not it's attached to a window.
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</p><p>
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If the <code class="classname">BScrollBar</code> is attached to a window, any change in its range will
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be immediately reflected on-screen. The knob will move to the appropriate
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position to reflect the current value.
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</p><p>
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Setting both the minimum and maximum to 0 disables the scroll bar. It
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will be drawn without a knob.
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</p><p>
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See also:
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The <code class="classname">BScrollBar</code>
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<a class="link" href="BScrollBar.html#BScrollBar_Constructor" title="BScrollBar()"><code class="methodname">constructor</code></a>
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_SetSteps"></a><a id="BScrollBar_GetSteps"></a>
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SetSteps(), GetSteps()</h4></div></div></div><code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">SetSteps</span>(<span class="methodparam"><span class="type">float </span><span class="parameter">smallStep</span></span>,<br /> <span class="methodparam"><span class="type">float </span><span class="parameter">bigStep</span></span>);</code><code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">GetSteps</span>(<span class="methodparam"><span class="type">float* </span><span class="parameter">smallStep</span></span>,<br /> <span class="methodparam"><span class="type">float* </span><span class="parameter">bigStep</span></span>) <span class="modifier">const</span>;</code><p>
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<code class="methodname">SetSteps()</code> sets how much a single user action should change the value of
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the scroll bar—and therefore how far the target view should scroll.
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<code class="methodname">GetSteps()</code> provides the current settings.
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</p><p>
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When the user presses one of the scroll arrows at either end of the
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scroll bar, its value changes by a <code class="parameter">smallStep</code> coordinate units. When the
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user clicks in the bar itself (other than on the knob), it changes by a
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<code class="parameter">bigStep</code> units. For an application that displays text, the small step of a
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vertical scroll bar should be large enough to bring another line of text
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into view.
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</p><p>
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The default small step is 1.0, which should be too small for most
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purposes; the default large step is 10.0, which is also probably too
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small.
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</p><div class="admonition note"><div class="title">Note</div><div class="graphic"><img class="icon" alt="Note" width="32" src="./images/admonitions/Info_32.png" /><div class="text"><p>Although the step values are specified using type <span class="type">float</span>, only integral
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values should be specified; otherwise, the scroll bar won't behave as
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expected.</p></div></div></div><p>
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Currently, a <code class="classname">BScrollBar</code>'s steps can be successfully set only after it's
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attached to a window.
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</p><p>
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See also:
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<a class="link" href="BScrollBar.html#BScrollBar_ValueChanged" title="ValueChanged()"><code class="methodname">ValueChanged()</code></a>
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</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_SetTarget"></a><a id="BScrollBar_Target"></a>
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SetTarget(), Target()</h4></div></div></div><div class="synopsisgroup">
|
||
<code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">SetTarget</span>(<span class="methodparam"><span class="type"><a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>* </span><span class="parameter">view</span></span>);</code>
|
||
|
||
<code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">SetTarget</span>(<span class="methodparam"><span class="modifier">const </span><span class="type">char* </span><span class="parameter">name</span></span>);</code>
|
||
</div><code class="methodsynopsis cpp"><span class="type"><a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>* </span><span class="methodname">Target</span>() <span class="modifier">const</span>;</code><p>
|
||
These functions set and return the target of the <code class="classname">BScrollBar</code>, the view
|
||
that the scroll bar scrolls. <code class="methodname">SetTarget()</code> sets the target to
|
||
<code class="parameter">view</code>, or to
|
||
the <a class="link" href="BView.html" title="BView"><code class="classname">BView</code></a>
|
||
identified by <code class="parameter">name</code>. <code class="methodname">Target()</code> returns the current target view.
|
||
The target can also be set when the <code class="classname">BScrollBar</code> is constructed.
|
||
</p><p>
|
||
<code class="methodname">SetTarget()</code> can be called either before or after the
|
||
<code class="classname">BScrollBar</code> is
|
||
attached to a window. If the target is set by <code class="parameter">name</code>, the named view must
|
||
eventually be found within the same window as the scroll bar. Typically,
|
||
the target and its scroll bars are children of a container view that
|
||
serves to bind them together as a unit.
|
||
</p><p>
|
||
When the target is successfully set, a pointer to the <code class="classname">BScrollBar</code> object
|
||
is passed to the target view. This lets the target update its scroll bars
|
||
when its contents are scrolled.
|
||
</p><p>
|
||
See also:
|
||
The <code class="classname">BScrollBar</code>
|
||
<a class="link" href="BScrollBar.html#BScrollBar_Constructor" title="BScrollBar()"><code class="methodname">constructor</code></a>,
|
||
<a class="link" href="BScrollBar.html#BScrollBar_ValueChanged" title="ValueChanged()"><code class="methodname">ValueChanged()</code></a>,
|
||
<a class="link" href="BView.html#BView_ScrollBar" title="ScrollBar()"><code class="methodname">BView::ScrollBar()</code></a>
|
||
</p></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_SetValue"></a><a id="BScrollBar_Value"></a>
|
||
SetValue(), Value()</h4></div></div></div><code class="methodsynopsis cpp"><span class="void">void </span><span class="methodname">SetValue</span>(<span class="methodparam"><span class="type">float </span><span class="parameter">value</span></span>);</code><code class="methodsynopsis cpp"><span class="type">float </span><span class="methodname">Value</span>() <span class="modifier">const</span>;</code><p>
|
||
These functions modify and return the value of the scroll bar. The value
|
||
is usually set as the result of user actions; <code class="methodname">SetValue()</code> provides a way
|
||
to do it programmatically. <code class="methodname">Value()</code> returns the current value, whether set
|
||
by <code class="methodname">SetValue()</code> or by the user.
|
||
</p><p>
|
||
<code class="methodname">SetValue()</code> assigns a new <code class="parameter">value</code> to the scroll bar and calls the
|
||
<a class="link" href="BScrollBar.html#BScrollBar_ValueChanged" title="ValueChanged()"><code class="methodname">ValueChanged()</code></a>
|
||
hook function, whether or not the new value is really a
|
||
change from the old. If the value passed lies outside the range of the
|
||
scroll bar, the <code class="classname">BScrollBar</code> is reset to the closest value within
|
||
range—that is, to either the minimum or the maximum value
|
||
previously specified.
|
||
</p><p>
|
||
If the scroll bar is attached to a window, changing its value updates its
|
||
on-screen display. The call to
|
||
<a class="link" href="BScrollBar.html#BScrollBar_ValueChanged" title="ValueChanged()"><code class="methodname">ValueChanged()</code></a>
|
||
enables the object to
|
||
scroll the target view so that it too is updated to conform to the new
|
||
value.
|
||
</p><p>
|
||
The initial value of a scroll bar is 0.
|
||
</p><p>
|
||
See also:
|
||
<a class="link" href="BScrollBar.html#BScrollBar_ValueChanged" title="ValueChanged()"><code class="methodname">ValueChanged()</code></a>,
|
||
<a class="link" href="BScrollBar.html#BScrollBar_SetRange" title="SetRange(), GetRange()"><code class="methodname">SetRange()</code></a>
|
||
</p></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="BScrollBar_StaticFunctions"></a>Static Functions</h3></div></div></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h4 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BScrollBar_Instantiate"></a>Instantiate()</h4></div></div></div><code class="methodsynopsis cpp"><span class="modifier">static </span><span class="type"><a class="link" href="BArchivable.html" title="BArchivable"><code class="classname">BArchivable</code></a>* </span><span class="methodname">Instantiate</span>(<span class="methodparam"><span class="type"><a class="link" href="BMessage.html" title="BMessage"><code class="classname">BMessage</code></a>* </span><span class="parameter">archive</span></span>);</code><p>
|
||
Returns a new <code class="classname">BScrollBar</code> object, allocated by new and created with the
|
||
version of the constructor that takes a
|
||
<a class="link" href="BMessage.html" title="BMessage"><code class="classname">BMessage</code></a> archive. However, if the
|
||
<code class="parameter">archive</code> message doesn't contain data for a <code class="classname">BScrollBar</code> object, the return
|
||
value will be <code class="constant">NULL</code>.
|
||
</p><p>
|
||
See also:
|
||
<a class="link" href="BArchivable.html#BArchivable_Instantiate" title="Instantiate()"><code class="methodname">BArchivable::Instantiate()</code></a>,
|
||
<a class="link" href="TheSupportKit_Functions.html#instantiate_object" title="instantiate_object()"><code class="function">instantiate_object()</code></a>,
|
||
<a class="link" href="BScrollBar.html#BScrollBar_Archive" title="Archive()"><code class="methodname">Archive()</code></a>
|
||
</p></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="BScrollBar_ArchivedFields"></a>Archived Fields</h3></div></div></div><p>
|
||
The <a class="link" href="BScrollBar.html#BScrollBar_Archive" title="Archive()"><code class="methodname">Archive()</code></a>
|
||
function adds the following fields to its
|
||
<a class="link" href="BMessage.html" title="BMessage"><code class="classname">BMessage</code></a> argument:
|
||
</p><div class="informaltable"><table border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th>Field</th><th>Type code</th><th>Description</th></tr></thead><tbody><tr><td><code class="varname">_range</code> (array)</td><td><code class="constant">B_FLOAT_TYPE</code></td><td>Minimum and maximum values of the scroll bar.</td></tr><tr><td><code class="varname">_steps</code> (array)</td><td><code class="constant">B_FLOAT_TYPE</code></td><td>Small and large steps of the scroll bar.</td></tr><tr><td><code class="varname">_val</code></td><td><code class="constant">B_FLOAT_TYPE</code></td><td>Current value of the scroll bar</td></tr><tr><td><code class="varname">_orient</code></td><td><code class="constant">B_INT32_TYPE</code></td><td>Orientation of the scroll bar.</td></tr><tr><td><code class="varname">_prop</code></td><td><code class="constant">B_FLOAT_TYPE</code></td><td>Proportion of the document visible in the target view.</td></tr></tbody></table></div></div></div><div id="footer"><hr /><div id="footerT">Prev: <a href="BScreen.html">BScreen</a> Up: <a href="TheInterfaceKit.html">The Interface Kit</a> Next: <a href="BScrollView.html">BScrollView</a> </div><div id="footerB"><div id="footerBL"><a href="BScreen.html" title="BScreen"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a href="TheInterfaceKit.html" title="The Interface Kit"><img src="./images/navigation/up.png" alt="Up" /></a> <a href="BScrollView.html" title="BScrollView"><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
|
||
<a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative
|
||
Commons Attribution-Non commercial-No Derivative Works 3.0 License</a>.</span></div></div></body></html>
|