GtkScale

GtkScale — A slider widget for selecting a value from a range

Properties

gint digits Read / Write
gboolean draw-value Read / Write
gboolean has-origin Read / Write
GtkPositionType value-pos Read / Write

Style Properties

Types and Values

struct GtkScale

Object Hierarchy

    GObject
    ╰── GInitiallyUnowned
        ╰── GtkWidget
            ╰── GtkRange
                ╰── GtkScale
                    ├── GtkHScale
                    ╰── GtkVScale

Implemented Interfaces

GtkScale implements AtkImplementorIface, GtkBuildable and GtkOrientable.

Includes

#include <gtk/gtk.h>

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

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
scale[.fine-tune][.marks-before][.marks-after]
├── marks.top
│   ├── mark
│   ┊    ├── [label]
│   ┊    ╰── indicator
┊   ┊
│   ╰── mark
├── [value]
├── contents
│   ╰── trough
│       ├── slider
│       ├── [highlight]
│       ╰── [fill]
╰── marks.bottom
    ├── mark
    ┊    ├── indicator
    ┊    ╰── [label]
    ╰── mark

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 ()

GtkWidget *
gtk_scale_new (GtkOrientation orientation,
               GtkAdjustment *adjustment);

Creates a new GtkScale.

Parameters

orientation

the scale’s orientation.

 

adjustment

the GtkAdjustment which sets the range of the scale, or NULL to create a new adjustment.

[nullable]

Returns

a new GtkScale

Since: 3.0


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.

Parameters

orientation

the scale’s orientation.

 

min

minimum value

 

max

maximum value

 

step

step increment (tick size) used with keyboard shortcuts

 

Returns

a new GtkScale

Since: 3.0


gtk_scale_set_digits ()

void
gtk_scale_set_digits (GtkScale *scale,
                      gint digits);

Sets the number of decimal places to which the value is rounded when it is changed. This also sets the number of digits shown in the displayed value when using the default handler for the “format-value” signal.

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.

Parameters

scale

a GtkScale

 

digits

the number of decimal places to which the value will be rounded

 

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.

Parameters

scale

a GtkScale

 

draw_value

TRUE to draw the value

 

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 scale between the origin (bottom or left side) of the scale and the current value.

Parameters

scale

a GtkScale

 

has_origin

TRUE if the scale has an origin

 

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.

Parameters

scale

a GtkScale

 

pos

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 to which the value is rounded on change. This number is also used by the default “format-value” handler.

Parameters

scale

a GtkScale

 

Returns

the number of decimal places


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.

Parameters

scale

a GtkScale

 

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.

Parameters

scale

a GtkScale

 

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.

Parameters

scale

a GtkScale

 

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.

Parameters

scale

A GtkScale

 

Returns

the PangoLayout for this scale, or NULL if the “draw-value” property is FALSE.

[transfer none][nullable]

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.

Parameters

scale

a GtkScale

 

x

location to store X offset of layout, or NULL.

[out][allow-none]

y

location to store Y offset of layout, or NULL.

[out][allow-none]

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().

Parameters

scale

a GtkScale

 

value

the value at which the mark is placed, must be between the lower and upper limits of the scales’ adjustment

 

position

where to draw the mark. For a horizontal scale, GTK_POS_TOP and GTK_POS_LEFT are drawn above the scale, anything else below. For a vertical scale, GTK_POS_LEFT and GTK_POS_TOP are drawn to the left of the scale, anything else to the right.

 

markup

Text to be shown at the mark, using Pango markup, or NULL.

[allow-none]

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().

Parameters

scale

a GtkScale

 

Since: 2.16

Types and Values

struct GtkScale

struct GtkScale;

Property Details

The “digits” property

  “digits”                   gint

The number of decimal places to which the value is rounded when it is changed. This also sets the number of digits shown in the displayed value when using the default handler for the “format-value” signal.

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.

Flags: Read / Write

Default value: TRUE


The “has-origin” property

  “has-origin”               gboolean

Whether the scale has an origin.

Flags: Read / Write

Default value: TRUE


The “value-pos” property

  “value-pos”                GtkPositionType

The position in which the current value is displayed.

Flags: Read / Write

Default value: GTK_POS_TOP

Style Property Details

The “slider-length” style property

  “slider-length”            gint

Length of scale's slider.

GtkScale:slider-length has been deprecated since version 3.20 and should not be used in newly-written code.

Use min-height/min-width CSS properties on the slider element instead. The value of this style property is ignored.

Flags: Read

Allowed values: >= 0

Default value: 31


The “value-spacing” style property

  “value-spacing”            gint

Space between value text and the slider/trough area.

GtkScale:value-spacing has been deprecated since version 3.20 and should not be used in newly-written code.

Use min-height/min-width CSS properties on the value element instead. The value of this style property is ignored.

Flags: Read

Allowed values: >= 0

Default value: 2

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<--".

1
2
3
4
5
6
7
static gchar*
format_value_callback (GtkScale *scale,
                       gdouble   value)
{
  return g_strdup_printf ("-->\%0.*g<--",
                          gtk_scale_get_digits (scale), value);
 }

Parameters

scale

the object which received the signal

 

value

the value to format

 

user_data

user data set when the signal handler was connected.

 

Returns

allocated string representing value

Flags: Run Last