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<!-- ##### SECTION Title ##### -->
GtkAdjustment
<!-- ##### SECTION Short_Description ##### -->
A GtkObject representing an adjustable bounded value
<!-- ##### SECTION Long_Description ##### -->
<para>
The #GtkAdjustment object represents a value which has an associated lower
and upper bound, together with step and page increments, and a page size.
It is used within several GTK+ widgets, including
#GtkSpinButton, #GtkViewport, and #GtkRange (which is a base class for
#GtkHScrollbar, #GtkVScrollbar, #GtkHScale, and #GtkVScale).
</para>
<para>
The #GtkAdjustment object does not update the value itself. Instead
it is left up to the owner of the #GtkAdjustment to control the value.
</para>
<para>
The owner of the #GtkAdjustment typically calls the
gtk_adjustment_value_changed() and gtk_adjustment_changed() functions
after changing the value and its bounds. This results in the emission of the
"value_changed" or "changed" signal respectively.
</para>
<!-- ##### SECTION See_Also ##### -->
<para>
</para>
<!-- ##### STRUCT GtkAdjustment ##### -->
<para>
The #GtkAdjustment-struct struct contains the following fields.
<informaltable pgwide="1" frame="none" role="struct">
<tgroup cols="2"><colspec colwidth="2*"/><colspec colwidth="8*"/>
<tbody>
<row>
<entry>#gdouble lower;</entry>
<entry>the minimum value.</entry>
</row>
<row>
<entry>#gdouble upper;</entry>
<entry>the maximum value.</entry>
</row>
<row>
<entry>#gdouble value;</entry>
<entry>the current value.</entry>
</row>
<row>
<entry>#gdouble step_increment;</entry>
<entry>the increment to use to make minor changes to the value.
In a #GtkScrollbar this increment is used when the mouse is clicked on the
arrows at the top and bottom of the scrollbar, to scroll by a small amount.
</entry>
</row>
<row>
<entry>#gdouble page_increment;</entry>
<entry>the increment to use to make major changes to the value.
In a #GtkScrollbar this increment is used when the mouse is clicked in the
trough, to scroll by a large amount.
</entry>
</row>
<row>
<entry>#gdouble page_size;</entry>
<entry>the page size.
In a #GtkScrollbar this is the size of the area which is currently visible.
</entry>
</row>
</tbody></tgroup></informaltable>
</para>
<!-- ##### SIGNAL GtkAdjustment::changed ##### -->
<para>
Emitted when one or more of the #GtkAdjustment fields have been changed,
other than the value field.
</para>
@adjustment: the object which received the signal.
<!-- ##### SIGNAL GtkAdjustment::value-changed ##### -->
<para>
Emitted when the #GtkAdjustment value field has been changed.
</para>
@adjustment: the object which received the signal.
<!-- ##### FUNCTION gtk_adjustment_new ##### -->
<para>
Creates a new #GtkAdjustment.
</para>
@value: the initial value.
@lower: the minimum value.
@upper: the maximum value.
@step_increment: the step increment.
@page_increment: the page increment.
@page_size: the page size.
@Returns: a new #GtkAdjustment.
<!-- ##### FUNCTION gtk_adjustment_get_value ##### -->
<para>
</para>
@adjustment:
@Returns:
<!-- ##### FUNCTION gtk_adjustment_set_value ##### -->
<para>
Sets the #GtkAdjustment value. The value is clamped to lie between
<literal>adjustment->lower</literal> and
<literal>adjustment->upper</literal>.
</para>
<para>
Note that for adjustments which are used in a #GtkScrollbar, the effective
range of allowed values goes from <literal>adjustment->lower</literal> to
<literal>adjustment->upper - adjustment->page_size</literal>.
</para>
@adjustment: a #GtkAdjustment.
@value: the new value.
<!-- ##### FUNCTION gtk_adjustment_clamp_page ##### -->
<para>
Updates the #GtkAdjustment @value to ensure that the range between @lower
and @upper is in the current page (i.e. between @value and @value +
@page_size).
If the range is larger than the page size, then only the start of it will
be in the current page.
A "changed" signal will be emitted if the value is changed.
</para>
@adjustment: a #GtkAdjustment.
@lower: the lower value.
@upper: the upper value.
<!-- ##### FUNCTION gtk_adjustment_changed ##### -->
<para>
Emits a "changed" signal from the #GtkAdjustment.
This is typically called by the owner of the #GtkAdjustment after it has
changed any of the #GtkAdjustment fields other than the value.
</para>
@adjustment:
<!-- ##### FUNCTION gtk_adjustment_value_changed ##### -->
<para>
Emits a "value_changed" signal from the #GtkAdjustment.
This is typically called by the owner of the #GtkAdjustment after it has
changed the #GtkAdjustment value field.
</para>
@adjustment:
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