forked from AuroraMiddleware/gtk
1499455d25
* gtk/tmpl/gtkadjustment.sgml: Document allowed values for adjustments which are used in scrollbars. (#108448, Ernst Lippe)
171 lines
4.5 KiB
Plaintext
171 lines
4.5 KiB
Plaintext
<!-- ##### SECTION Title ##### -->
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GtkAdjustment
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<!-- ##### SECTION Short_Description ##### -->
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A GtkObject representing an adjustable bounded value
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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The #GtkAdjustment object represents a value which has an associated lower
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and upper bound, together with step and page increments, and a page size.
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It is used within several GTK+ widgets, including
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#GtkSpinButton, #GtkViewport, and #GtkRange (which is a base class for
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#GtkHScrollbar, #GtkVScrollbar, #GtkHScale, and #GtkVScale).
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</para>
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<para>
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The #GtkAdjustment object does not update the value itself. Instead
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it is left up to the owner of the #GtkAdjustment to control the value.
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</para>
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<para>
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The owner of the #GtkAdjustment typically calls the
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gtk_adjustment_value_changed() and gtk_adjustment_changed() functions
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after changing the value and its bounds. This results in the emission of the
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"value_changed" or "changed" signal respectively.
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</para>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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</para>
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<!-- ##### STRUCT GtkAdjustment ##### -->
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<para>
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The #GtkAdjustment-struct struct contains the following fields.
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<informaltable pgwide="1" frame="none" role="struct">
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<tgroup cols="2"><colspec colwidth="2*"/><colspec colwidth="8*"/>
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<tbody>
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<row>
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<entry>#gdouble lower;</entry>
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<entry>the minimum value.</entry>
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</row>
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<row>
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<entry>#gdouble upper;</entry>
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<entry>the maximum value.</entry>
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</row>
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<row>
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<entry>#gdouble value;</entry>
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<entry>the current value.</entry>
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</row>
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<row>
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<entry>#gdouble step_increment;</entry>
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<entry>the increment to use to make minor changes to the value.
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In a #GtkScrollbar this increment is used when the mouse is clicked on the
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arrows at the top and bottom of the scrollbar, to scroll by a small amount.
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</entry>
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</row>
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<row>
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<entry>#gdouble page_increment;</entry>
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<entry>the increment to use to make major changes to the value.
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In a #GtkScrollbar this increment is used when the mouse is clicked in the
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trough, to scroll by a large amount.
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</entry>
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</row>
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<row>
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<entry>#gdouble page_size;</entry>
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<entry>the page size.
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In a #GtkScrollbar this is the size of the area which is currently visible.
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</entry>
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</row>
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</tbody></tgroup></informaltable>
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</para>
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<!-- ##### FUNCTION gtk_adjustment_new ##### -->
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<para>
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Creates a new #GtkAdjustment.
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</para>
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@value: the initial value.
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@lower: the minimum value.
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@upper: the maximum value.
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@step_increment: the step increment.
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@page_increment: the page increment.
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@page_size: the page size.
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@Returns: a new #GtkAdjustment.
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<!-- ##### FUNCTION gtk_adjustment_get_value ##### -->
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<para>
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</para>
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@adjustment:
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@Returns:
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<!-- ##### FUNCTION gtk_adjustment_set_value ##### -->
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<para>
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Sets the #GtkAdjustment value. The value is clamped to lie between
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<literal>adjustment->lower</literal> and
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<literal>adjustment->upper</literal>.
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</para>
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<para>
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Note that for adjustments which are used in a #GtkScrollbar, the effective
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range of allowed values goes from <literal>adjustment->lower</literal> to
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<literal>adjustment->upper - adjustment->page_size</literal>.
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</para>
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@adjustment: a #GtkAdjustment.
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@value: the new value.
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<!-- ##### FUNCTION gtk_adjustment_clamp_page ##### -->
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<para>
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Updates the #GtkAdjustment @value to ensure that the range between @lower
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and @upper is in the current page (i.e. between @value and @value +
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@page_size).
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If the range is larger than the page size, then only the start of it will
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be in the current page.
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A "changed" signal will be emitted if the value is changed.
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</para>
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@adjustment: a #GtkAdjustment.
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@lower: the lower value.
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@upper: the upper value.
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<!-- ##### FUNCTION gtk_adjustment_changed ##### -->
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<para>
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Emits a "changed" signal from the #GtkAdjustment.
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This is typically called by the owner of the #GtkAdjustment after it has
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changed any of the #GtkAdjustment fields other than the value.
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</para>
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@adjustment:
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<!-- ##### FUNCTION gtk_adjustment_value_changed ##### -->
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<para>
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Emits a "value_changed" signal from the #GtkAdjustment.
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This is typically called by the owner of the #GtkAdjustment after it has
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changed the #GtkAdjustment value field.
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</para>
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@adjustment:
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<!-- ##### SIGNAL GtkAdjustment::changed ##### -->
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<para>
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Emitted when one or more of the #GtkAdjustment fields have been changed,
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other than the value field.
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</para>
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@adjustment: the object which received the signal.
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<!-- ##### SIGNAL GtkAdjustment::value-changed ##### -->
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<para>
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Emitted when the #GtkAdjustment value field has been changed.
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</para>
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@adjustment: the object which received the signal.
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