path: root/lib/libXaw/specs/List.xml

<sect1 id="List_Widget">
<title>List Widget</title>
<para>
<!-- .LP -->
<!-- .XS -->
<!-- 	List Widget -->
<!-- .XE -->
<indexterm significance="preferred"><primary>List widget</primary></indexterm>
<literallayout class="monospaced">
<!-- .TA 2.0i -->
<!-- .ta 2.0i -->
<!-- .sp -->
Application header file	&lt;X11/Xaw/List.h&gt;
<indexterm><primary>List.h</primary></indexterm>
Class header file	&lt;X11/Xaw/ListP.h&gt;
<indexterm><primary>ListP.h</primary></indexterm>
Class	listWidgetClass
<indexterm><primary>listWidgetClass</primary></indexterm>
Class Name	List
<indexterm><primary>List widget</primary><secondary>class name</secondary></indexterm>
Superclass	Simple
<!-- .sp -->
</literallayout>
</para>
<para>
<!-- .LP -->

The List widget contains a list of strings formatted into rows and
columns. When one of the strings is selected, it is highlighted, and the
List widget's <function>Notify</function> action is invoked, calling all routines on
its callback list.  Only one string may be selected at a time.
</para>
<sect2 id='List::Resources'>
<title>Resources</title>
<para>
<!-- .LP -->
When creating a List widget instance, the following resources are
retrieved from the argument list or from the resource database:
</para>
<para>
<!-- .LP -->
<indexterm><primary>List widget</primary><secondary>resources</secondary></indexterm>
<informaltable>
  <tgroup cols='5' align='center'>
  <colspec colname='c1'/>
  <colspec colname='c2'/>
  <colspec colname='c3'/>
  <colspec colname='c4'/>
  <colspec colname='c5'/>
  <thead>
    <row>
      <entry>Name</entry>
      <entry>Class</entry>
      <entry>Type</entry>
      <entry>Notes</entry>
      <entry>Default Value</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>accelerators</entry>
      <entry>Accelerators</entry>
      <entry>AcceleratorTable</entry>
      <entry></entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>ancestorSensitive</entry>
      <entry>AncestorSensitive</entry>
      <entry>Boolean</entry>
      <entry>D</entry>
      <entry>True</entry>
    </row>
    <row>
      <entry>background</entry>
      <entry>Background</entry>
      <entry>Pixel</entry>
      <entry></entry>
      <entry>XtDefaultBackground</entry>
    </row>
    <row>
      <entry>backgroundPixmap</entry>
      <entry>Pixmap</entry>
      <entry>Pixmap</entry>
      <entry></entry>
      <entry>XtUnspecifiedPixmap</entry>
    </row>
    <row>
      <entry>borderColor</entry>
      <entry>BorderColor</entry>
      <entry>Pixel</entry>
      <entry></entry>
      <entry>XtDefaultForeground</entry>
    </row>
    <row>
      <entry>borderPixmap</entry>
      <entry>Pixmap</entry>
      <entry>Pixmap</entry>
      <entry></entry>
      <entry>XtUnspecifiedPixmap</entry>
    </row>
    <row>
      <entry>borderWidth</entry>
      <entry>BorderWidth</entry>
      <entry>Dimension</entry>
      <entry></entry>
      <entry>1</entry>
    </row>
    <row>
      <entry>callback</entry>
      <entry>Callback</entry>
      <entry>Callback</entry>
      <entry></entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>colormap</entry>
      <entry>Colormap</entry>
      <entry>Colormap</entry>
      <entry></entry>
      <entry>Parent's Colormap</entry>
    </row>
    <row>
      <entry>columnSpacing</entry>
      <entry>Spacing</entry>
      <entry>Dimension</entry>
      <entry></entry>
      <entry>6</entry>
    </row>
    <row>
      <entry>cursor</entry>
      <entry>Cursor</entry>
      <entry>Cursor</entry>
      <entry></entry>
      <entry>XC_left_ptr</entry>
    </row>
    <row>
      <entry>cursorName</entry>
      <entry>Cursor</entry>
      <entry>String</entry>
      <entry></entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>defaultColumns</entry>
      <entry>Columns</entry>
      <entry>int</entry>
      <entry></entry>
      <entry>2</entry>
    </row>
    <row>
      <entry>depth</entry>
      <entry>Depth</entry>
      <entry>int</entry>
      <entry>C</entry>
      <entry>Parent's Depth</entry>
    </row>
    <row>
      <entry>destroyCallback</entry>
      <entry>Callback</entry>
      <entry>XtCallbackList</entry>
      <entry></entry>
      <entry>NULL</entry>
    </row>
    <row>
      <entry>font</entry>
      <entry>Font</entry>
      <entry>FontStruct</entry>
      <entry></entry>
      <entry>XtDefaultFont</entry>
    </row>
    <row>
      <entry>fontSet</entry>
      <entry>FontSet</entry>
      <entry>XFontSet</entry>
      <entry></entry>
      <entry>XtDefaultFontSet</entry>
    </row>
    <row>
      <entry>forceColumns</entry>
      <entry>Columns</entry>
      <entry>Boolean</entry>
      <entry></entry>
      <entry>False</entry>
    </row>
    <row>
      <entry>foreground</entry>
      <entry>Foreground</entry>
      <entry>Pixel</entry>
      <entry></entry>
      <entry>XtDefaultForeground</entry>
    </row>
    <row>
      <entry>height</entry>
      <entry>Height</entry>
      <entry>Dimension</entry>
      <entry>A</entry>
      <entry>Enough space to contain the list</entry>
    </row>
    <row>
      <entry>insensitiveBorder</entry>
      <entry>Insensitive</entry>
      <entry>Pixmap</entry>
      <entry></entry>
      <entry>GreyPixmap</entry>
    </row>
    <row>
      <entry>internalHeight</entry>
      <entry>Height</entry>
      <entry>Dimension</entry>
      <entry></entry>
      <entry>2</entry>
    </row>
    <row>
      <entry>internalWidth</entry>
      <entry>Width</entry>
      <entry>Dimension</entry>
      <entry></entry>
      <entry>4</entry>
    </row>
    <row>
      <entry>international</entry>
      <entry>International</entry>
      <entry>Boolean</entry>
      <entry>C</entry>
      <entry>False</entry>
    </row>
    <row>
      <entry>list</entry>
      <entry>List</entry>
      <entry>Pointer</entry>
      <entry></entry>
      <entry>name of widget</entry>
    </row>
    <row>
      <entry>longest</entry>
      <entry>Longest</entry>
      <entry>int</entry>
      <entry>A</entry>
      <entry>0</entry>
    </row>
    <row>
      <entry>mappedWhenManaged</entry>
      <entry>MappedWhenManaged</entry>
      <entry>Boolean</entry>
      <entry></entry>
      <entry>True</entry>
    </row>
    <row>
      <entry>numberStrings</entry>
      <entry>NumberStrings</entry>
      <entry>int</entry>
      <entry>A</entry>
      <entry>computed for NULL terminated list</entry>
    </row>
    <row>
      <entry>pasteBuffer</entry>
      <entry>Boolean</entry>
      <entry>Boolean</entry>
      <entry></entry>
      <entry>False</entry>
    </row>
    <row>
      <entry>pointerColor</entry>
      <entry>Foreground</entry>
      <entry>Pixel</entry>
      <entry></entry>
      <entry>XtDefaultForeground</entry>
    </row>
    <row>
      <entry>pointerColorBackground</entry>
      <entry>Background</entry>
      <entry>Pixel</entry>
      <entry></entry>
      <entry>XtDefaultBackground</entry>
    </row>
    <row>
      <entry>rowSpacing</entry>
      <entry>Spacing</entry>
      <entry>Dimension</entry>
      <entry></entry>
      <entry>2</entry>
    </row>
    <row>
      <entry>screen</entry>
      <entry>Screen</entry>
      <entry>Screen</entry>
      <entry>R</entry>
      <entry>Parent's Screen</entry>
    </row>
    <row>
      <entry>sensitive</entry>
      <entry>Sensitive</entry>
      <entry>Boolean</entry>
      <entry></entry>
      <entry>True</entry>
    </row>
    <row>
      <entry>translations</entry>
      <entry>Translations</entry>
      <entry>TranslationTable</entry>
      <entry></entry>
      <entry>See below</entry>
    </row>
    <row>
      <entry>verticalList</entry>
      <entry>Boolean</entry>
      <entry>Boolean</entry>
      <entry></entry>
      <entry>False</entry>
    </row>
    <row>
      <entry>width</entry>
      <entry>Width</entry>
      <entry>Dimension</entry>
      <entry>A</entry>
      <entry>Enough space to contain the list</entry>
    </row>
    <row>
      <entry>x</entry>
      <entry>Position</entry>
      <entry>Position</entry>
      <entry></entry>
      <entry>0</entry>
    </row>
    <row>
      <entry>y</entry>
      <entry>Position</entry>
      <entry>Position</entry>
      <entry></entry>
      <entry>0</entry>
    </row>
    <row>
      <entry>_</entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>
<!-- .Ac -->
<!-- .As -->
<!-- .Bg -->
<!-- .Gp -->
<!-- .Bc -->
<!-- .Bp -->
<!-- .Bw -->
<variablelist>
  <varlistentry>
    <term>
      <function>callback</function>
    </term>
    <listitem>
      <para>
All functions on this list are called whenever the <function>notify</function> action is
invoked.  The <emphasis remap='I'>call_data</emphasis> argument contains information about the element
selected and is described in detail in the <function>List Callbacks</function> section.
<!-- .Cm -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>columnSpacing</function>
    </term>
    <listitem>
      <para>
<!-- .br -->
<!-- .ns -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>rowSpacing</function>
    </term>
    <listitem>
      <para>
The amount of space, in pixels, between each of the rows and columns
in the list.
<!-- .Cu -->
<!-- .Cn -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>defaultColumns</function>
    </term>
    <listitem>
      <para>
The default number of columns.  This value is used when neither the
width nor the height of the List widget is specified or when
<function>forceColumns</function> is <function>True</function>.
<!-- .Dp -->
<!-- .Dc -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>font</function>
    </term>
    <listitem>
      <para>
The text font to use when displaying the <function>list</function>, when the
<function>international</function> resource is <function>false</function>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>fontSet</function>
    </term>
    <listitem>
      <para>
The text font set to use when displaying the <function>list</function>, when the
<function>international</function> resource is <function>true</function>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>forceColumns</function>
    </term>
    <listitem>
      <para>
Forces the default number of columns to be used regardless of the
List widget's current size.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>foreground</function>
    </term>
    <listitem>
      <para>
A pixel value which indexes the widget's colormap to derive the color
used to paint the text of the list elements.
<!-- .Hw -->
<!-- .Ib -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>internalHeight</function>
    </term>
    <listitem>
      <para>
<!-- .br -->
<!-- .ns -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>internalWidth</function>
    </term>
    <listitem>
      <para>
The margin, in pixels, between the edges of the list and the
corresponding edge of the List widget's window.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>list</function>
    </term>
    <listitem>
      <para>
An array of text strings displayed in the List widget.  If
<function>numberStrings</function> is zero (the default) then the <function>list</function> must be
NULL terminated.  If a value is not specified for the <function>list</function>, then
<function>numberStrings</function> is set to 1, and the name of the widget is used as
the <function>list</function>, and <function>longest</function> is set to the length of the name of the
widget.  The <function>list</function> is used in place, and must be available
to the List widget for the lifetime of this widget, or until it is
changed with <xref linkend='XtSetValues' xrefstyle='select: title'/> or <xref linkend='XawListChange' xrefstyle='select: title'/>.
<!-- .In -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>longest</function>
    </term>
    <listitem>
      <para>
Specifies the width, in pixels, of the longest string in the current
list.  The List widget will compute this value if zero (the default)
is specified.  If this resource is set by hand, entries longer than this
will be clipped to fit.
<!-- .Mm -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>numberStrings</function>
    </term>
    <listitem>
      <para>
The number of strings in the current list.  If a value of zero (the
default) is specified, the List widget will compute it.  When computing
the number of strings the List widget assumes that the <function>list</function> is NULL
terminated.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>pasteBuffer</function>
    </term>
    <listitem>
      <para>
If this resource is set to <function>True</function> then the name of the currently
selected list element will be put into <function>CUT_BUFFER_0</function>.
<!-- .Pf -->
<!-- .Pb -->
<!-- .Sc -->
<!-- .Se -->
<!-- .Tr -->
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>verticalList</function>
    </term>
    <listitem>
      <para>
If this resource is set to <function>True</function> then the list elements will be
presented in column major order.
<!-- .Xy -->
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
</sect2>
<sect2 id="List_Actions">
<title>List Actions</title>
<indexterm><primary>List widget</primary><secondary>actions</secondary></indexterm>
<para>
<!-- .LP -->
The List widget supports the following actions:
</para>
<itemizedlist>
  <listitem>
    <para>
Highlighting and unhighlighting the list element under the
pointer with <function>Set</function> and <function>Unset</function>
    </para>
  </listitem>
  <listitem>
    <para>
Processing application callbacks with <function>Notify</function>
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
The following is the default translation table used by the List Widget:
<indexterm><primary>List widget</primary><secondary>default translation table</secondary></indexterm>
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i 2.25i -->
<!-- .ta .5i 2.25i -->
&lt;Btn1Down&gt;,&lt;Btn1Up&gt;:	Set(&#x2006;) Notify(&#x2006;)
<!-- .sp -->
</literallayout>
</para>
<para>
<!-- .LP -->
The full list of actions supported by List widget is:
<variablelist>
  <varlistentry>
    <term>
      <function>Set</function>(&#x2006;)
    </term>
    <listitem>
      <para>
<emphasis remap='I'>Sets</emphasis> the list element that is currently under the pointer.  To
inform the user that this element is currently set, it is drawn with
foreground and background colors reversed.  If this action is called when
there is no list element under the cursor, the currently <emphasis remap='I'>set</emphasis>
element will be <emphasis remap='I'>unset</emphasis>.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>Unset</function>(&#x2006;)
    </term>
    <listitem>
      <para>
Cancels the <emphasis remap='I'>set</emphasis> state of the element under the pointer,
and redraws it with normal foreground and background colors.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <function>Notify</function>(&#x2006;)
    </term>
    <listitem>
      <para>
Calls all callbacks on the List widget's callback list.  Information
about the currently selected list element is passed in the
<emphasis remap='I'>call_data</emphasis> argument (see <function>List Callbacks</function> below).
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
</sect2>
<sect2 id="List_Callbacks">
<title>List Callbacks</title>
<indexterm><primary>List widget</primary><secondary>callbacks</secondary></indexterm>
<para>
<!-- .LP -->
All procedures on the List widget's callback list will have a
<function>XawListReturnStruct</function> passed to them as <emphasis remap='I'>call_data</emphasis>.  The
structure is defined in the List widget's application header file.
</para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i 2.25i -->
<!-- .ta .5i 2.25i -->
<indexterm significance="preferred"><primary>XawListReturnStruct</primary></indexterm>
typedef struct _XawListReturnStruct {
	String string;	/* string shown in the list. */
	int list_index;	/* index of the item selected. */
} XawListReturnStruct;
<indexterm><primary>XawListReturnStruct</primary></indexterm>
<!-- .NT -->
</literallayout>
<note><para>
The <emphasis remap='I'>list_index</emphasis> item used to be called simply <emphasis remap='I'>index</emphasis>.
Unfortunately, this name collided with a global name defined on some
operating systems, and had to be changed.
</para></note>
<!-- .NE -->
</sect2>
<sect2 id="Changing_the_List">
<title>Changing the List</title>
<para>
<!-- .LP -->
To change the list that is displayed, use
<function>XawListChange</function>.
<indexterm significance="preferred"><primary>XawListChange</primary></indexterm>
<funcsynopsis id='XawListChange'>
<funcprototype>
  <funcdef>void<function> XawListChange</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>String*<parameter> list</parameter></paramdef>
  <paramdef>intnitems,<parameter> longest</parameter></paramdef>
  <paramdef>Boolean<parameter> resize</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the List widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>list</emphasis>
    </term>
    <listitem>
      <para>
Specifies the new list for the List widget to display.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>nitems</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of items in the <emphasis remap='I'>list</emphasis>.  If a value less than 1
is specified, <emphasis remap='I'>list</emphasis> must be NULL terminated, and the number of
items will be calculated by the List widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>longest</emphasis>
    </term>
    <listitem>
      <para>
Specifies the length of the longest item in the <emphasis remap='I'>list</emphasis> in pixels.
If a value less than 1 is specified, the List widget will calculate the
value.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>resize</emphasis>
    </term>
    <listitem>
      <para>
Specifies a Boolean value that if <function>True</function> indicates that the
List widget should try to resize itself after making the change.
The constraints of the List widget's parent are always enforced,
regardless of the value specified here.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<xref linkend='XawListChange' xrefstyle='select: title'/>
will <emphasis remap='I'>unset</emphasis> all list elements that are currently <function>set</function> before
the list is actually changed.  The <emphasis remap='I'>list</emphasis> is used in place, and must
remain usable for the lifetime of the List widget, or until <emphasis remap='I'>list</emphasis>
has been changed again with this function or with <xref linkend='XtSetValues' xrefstyle='select: title'/>.
</para>
</sect2>
<sect2 id="Highlighting_an_Item">
<title>Highlighting an Item</title>
<para>
<!-- .LP -->
To highlight an item in the list, use
<function>XawListHighlight</function>.
<indexterm significance="preferred"><primary>XawListHighlight</primary></indexterm>
<funcsynopsis id='XawListHighlight'>
<funcprototype>
  <funcdef>void<function> XawListHighlight</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
  <paramdef>int<parameter> item</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the List widget.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>item</emphasis>
    </term>
    <listitem>
      <para>
Specifies an index into the current list that indicates the item to be
highlighted.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
Only one item can be highlighted at a time.
If an item is already highlighted when
<xref linkend='XawListHighlight' xrefstyle='select: title'/>
is called,
the highlighted item is unhighlighted before the new item is highlighted.
</para>
</sect2>
<sect2 id="Unhighlighting_an_Item">
<title>Unhighlighting an Item</title>
<para>
<!-- .LP -->
To unhighlight the currently highlighted item in the list, use
<function>XawListUnhighlight</function>.
<indexterm significance="preferred"><primary>XawListUnhighlight</primary></indexterm>
<funcsynopsis id='XawListUnhighlight'>
<funcprototype>
  <funcdef>void<function> XawListUnhighlight</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the List widget.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
</sect2>
<sect2 id="Retrieving_the_Currently_Selected_Item">
<title>Retrieving the Currently Selected Item</title>
<para>
<!-- .LP -->
To retrieve the list element that is currently <emphasis remap='I'>set</emphasis>, use
<function>XawListShowCurrent</function>.
<indexterm significance="preferred"><primary>XawListShowCurrent</primary></indexterm>
<funcsynopsis id='XawListShowCurrent'>
<funcprototype>
  <funcdef>XawListReturnStruct<function> *XawListShowCurrent</function></funcdef>
  <paramdef>Widget<parameter> w</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>w</emphasis>
    </term>
    <listitem>
      <para>
Specifies the List widget.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<function>XawListShowCurrent</function>
returns a pointer to an
<function>XawListReturnStruct</function>
structure,
containing the currently highlighted item.
If the value of the index member is XAW_LIST_NONE,
<indexterm><primary>XAW_LIST_NONE</primary></indexterm>
the string member is undefined, and no item is currently selected.
</para>
</sect2>
<sect2 id="Restrictions">
<title>Restrictions</title>
<para>
<!-- .LP -->
Many programmers create a <quote>scrolled list</quote> by putting a List
widget with many entries as a child of a Viewport widget.  The
List continues to create a window as big as its contents, but
that big window is only visible where it intersects the parent
Viewport's window.  (I.e., it is <quote>clipped.</quote>)
</para>
<para>
<!-- .LP -->
While this is a useful technique, there is a serious drawback.
X does not support windows above 32,767 pixels in width or
height, but this height limit will be exceeded by a List's
window when the List has many entries (i.e., with a 12 point
font, about 3000 entries would be too many.)
</para>
<para>
<!-- .LP -->

</para>
</sect2>
</sect1>