Description
A GtkScale is a slider control used to select a numeric value.
To use it, you’ll probably want to investigate the methods on
its base class, GtkRange, in addition to the methods for GtkScale itself.
To set the value of a scale, you would normally use gtk_range_set_value().
To detect changes to the value, you would normally use the
“value-changed” signal.
Note that using the same upper and lower bounds for the GtkScale (through
the GtkRange methods) will hide the slider itself. This is useful for
applications that want to show an undeterminate value on the scale, without
changing the layout of the application (such as movie or music players).
GtkScale as GtkBuildable
GtkScale supports a custom <marks> element, which can contain multiple
<mark> elements. The “value” and “position” attributes have the same
meaning as gtk_scale_add_mark() parameters of the same name. If the
element is not empty, its content is taken as the markup to show at
the mark. It can be translated with the usual ”translatable” and
“context” attributes.
CSS nodes
GtkScale has a main CSS node with name scale and a subnode for its contents,
with subnodes named trough and slider.
The main node gets the style class .fine-tune added when the scale is in
'fine-tuning' mode.
If the scale has an origin (see gtk_scale_set_has_origin()), there is a
subnode with name highlight below the trough node that is used for rendering
the highlighted part of the trough.
If the scale is showing a fill level (see gtk_range_set_show_fill_level()),
there is a subnode with name fill below the trough node that is used for
rendering the filled in part of the trough.
If marks are present, there is a marks subnode before or after the contents
node, below which each mark gets a node with name mark. The marks nodes get
either the .top or .bottom style class.
The mark node has a subnode named indicator. If the mark has text, it also
has a subnode named label. When the mark is either above or left of the
scale, the label subnode is the first when present. Otherwise, the indicator
subnode is the first.
The main CSS node gets the 'marks-before' and/or 'marks-after' style classes
added depending on what marks are present.
If the scale is displaying the value (see “draw-value”), there is
subnode with name value.
Functions
gtk_scale_new_with_range ()
GtkWidget *
gtk_scale_new_with_range (GtkOrientation orientation,
gdouble min,
gdouble max,
gdouble step);
Creates a new scale widget with the given orientation that lets the
user input a number between min
and max
(including min
and max
)
with the increment step
. step
must be nonzero; it’s the distance
the slider moves when using the arrow keys to adjust the scale
value.
Note that the way in which the precision is derived works best if step
is a power of ten. If the resulting precision is not suitable for your
needs, use gtk_scale_set_digits() to correct it.
Since: 3.0
gtk_scale_set_digits ()
void
gtk_scale_set_digits (GtkScale *scale,
gint digits);
Sets the number of decimal places that are displayed in the value. Also
causes the value of the adjustment to be rounded to this number of digits,
so the retrieved value matches the displayed one, if “draw-value” is
TRUE when the value changes. If you want to enforce rounding the value when
“draw-value” is FALSE, you can set “round-digits” instead.
Note that rounding to a small number of digits can interfere with
the smooth autoscrolling that is built into GtkScale. As an alternative,
you can use the “format-value” signal to format the displayed
value yourself.
gtk_scale_set_draw_value ()
void
gtk_scale_set_draw_value (GtkScale *scale,
gboolean draw_value);
Specifies whether the current value is displayed as a string next
to the slider.
gtk_scale_set_has_origin ()
void
gtk_scale_set_has_origin (GtkScale *scale,
gboolean has_origin);
If “has-origin” is set to TRUE (the default), the scale will
highlight the part of the trough between the origin (bottom or left side)
and the current value.
Since: 3.4
gtk_scale_set_value_pos ()
void
gtk_scale_set_value_pos (GtkScale *scale,
GtkPositionType pos);
Sets the position in which the current value is displayed.
gtk_scale_get_digits ()
gint
gtk_scale_get_digits (GtkScale *scale);
Gets the number of decimal places that are displayed in the value.
Returns
the number of decimal places that are displayed
gtk_scale_get_draw_value ()
gboolean
gtk_scale_get_draw_value (GtkScale *scale);
Returns whether the current value is displayed as a string
next to the slider.
Returns
whether the current value is displayed as a string
gtk_scale_get_has_origin ()
gboolean
gtk_scale_get_has_origin (GtkScale *scale);
Returns whether the scale has an origin.
Returns
TRUE if the scale has an origin.
Since: 3.4
gtk_scale_get_value_pos ()
GtkPositionType
gtk_scale_get_value_pos (GtkScale *scale);
Gets the position in which the current value is displayed.
Returns
the position in which the current value is displayed
gtk_scale_get_layout ()
PangoLayout *
gtk_scale_get_layout (GtkScale *scale);
Gets the PangoLayout used to display the scale. The returned
object is owned by the scale so does not need to be freed by
the caller.
Since: 2.4
gtk_scale_get_layout_offsets ()
void
gtk_scale_get_layout_offsets (GtkScale *scale,
gint *x,
gint *y);
Obtains the coordinates where the scale will draw the
PangoLayout representing the text in the scale. Remember
when using the PangoLayout function you need to convert to
and from pixels using PANGO_PIXELS() or PANGO_SCALE.
If the “draw-value” property is FALSE, the return
values are undefined.
Since: 2.4
gtk_scale_add_mark ()
void
gtk_scale_add_mark (GtkScale *scale,
gdouble value,
GtkPositionType position,
const gchar *markup);
Adds a mark at value
.
A mark is indicated visually by drawing a tick mark next to the scale,
and GTK+ makes it easy for the user to position the scale exactly at the
marks value.
If markup
is not NULL, text is shown next to the tick mark.
To remove marks from a scale, use gtk_scale_clear_marks().
Since: 2.16
gtk_scale_clear_marks ()
void
gtk_scale_clear_marks (GtkScale *scale);
Removes any marks that have been added with gtk_scale_add_mark().
Since: 2.16
Property Details
The “digits” property
“digits” gint
The number of decimal places that are displayed in the value.
Owner: GtkScale
Flags: Read / Write
Allowed values: [-1,64]
Default value: 1
The “draw-value” property
“draw-value” gboolean
Whether the current value is displayed as a string next to the slider.
Owner: GtkScale
Flags: Read / Write
Default value: TRUE
The “has-origin” property
“has-origin” gboolean
Whether the scale has an origin.
Owner: GtkScale
Flags: Read / Write
Default value: TRUE
The “value-pos” property
“value-pos” GtkPositionType
The position in which the current value is displayed.
Owner: GtkScale
Flags: Read / Write
Default value: GTK_POS_TOP
Signal Details
The “format-value” signal
gchar*
user_function (GtkScale *scale,
gdouble value,
gpointer user_data)
Signal which allows you to change how the scale value is displayed.
Connect a signal handler which returns an allocated string representing
value
. That string will then be used to display the scale's value.
If no user-provided handlers are installed, the value will be displayed on
its own, rounded according to the value of the “digits” property.
Here's an example signal handler which displays a value 1.0 as
with "-->1.0<--".
Returns
allocated string representing value
Flags: Run Last