## GtkScale

GtkScale — a base class for GtkHScale and GtkVScale.

## Synopsis

    #include <gtk/gtk.h>

    struct      GtkScale;
    void        gtk_scale_set_digits            (GtkScale *scale,
                                                 gint digits);
    void        gtk_scale_set_draw_value        (GtkScale *scale,
                                                 gboolean draw_value);
    void        gtk_scale_set_value_pos         (GtkScale *scale,
                                                 GtkPositionType pos);
    gint        gtk_scale_get_digits            (GtkScale *scale);
    gboolean    gtk_scale_get_draw_value        (GtkScale *scale);
    GtkPositionType gtk_scale_get_value_pos     (GtkScale *scale);
    PangoLayout* gtk_scale_get_layout           (GtkScale *scale);
    void        gtk_scale_get_layout_offsets    (GtkScale *scale,
                                                 gint *x,
                                                 gint *y);

## Object Hierarchy

      GObject
       +----GtkObject
             +----GtkWidget
                   +----GtkRange
                         +----GtkScale
                               +----GtkHScale
                               +----GtkVScale

## Implemented Interfaces

GtkScale implements AtkImplementorIface.

## Properties

      "digits"               gint                 : Read / Write
      "draw-value"           gboolean             : Read / Write
      "value-pos"            GtkPositionType      : Read / Write

## Style Properties

      "slider-length"        gint                 : Read
      "value-spacing"        gint                 : Read

## Signal Prototypes

    "format-value"
                gchar*      user_function      (GtkScale *scale,
                                                gdouble arg1,
                                                gpointer user_data);

## 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.

The GtkScale widget is an abstract class, used only for deriving the subclasses GtkHScale and GtkVScale. To create a scale widget, call `gtk_hscale_new_with_range()` or `gtk_vscale_new_with_range()`.

## Details

### struct GtkScale

    struct GtkScale;

The GtkScale-struct struct contains the following fields. (These fields should be considered read-only. They should never be set by an application.)

guint `draw_value`; | non-zero if the scale's current value is displayed next to the slider.
guint `value_pos`; | the position in which the textual value is displayed, selected from GtkPositionType.

### 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 off to this number of digits, so the retrieved value matches the value the user saw.

`scale` : | a GtkScale.
`digits` : | the number of decimal places to display, e.g. use 1 to display 1.0, 2 to display 1.00 etc.

### 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.

`scale` : | a GtkScale.
`draw_value` : | a boolean.

### 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.

`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 that are displayed in the value.

`scale` : | a GtkScale.
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.

`scale` : | a GtkScale.
Returns : | whether the current value is displayed as a string.

### gtk_scale_get_value_pos ()

    GtkPositionType gtk_scale_get_value_pos     (GtkScale *scale);

Gets the position in which the current value is displayed.

`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.

`scale` : | A GtkScale
Returns : | the PangoLayout for this scale, or `NULL` if the draw_value property is `FALSE`.

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.

`scale` : | a GtkScale
`x` : | location to store X offset of layout, or `NULL`
`y` : | location to store Y offset of layout, or `NULL`

Since 2.4

## Properties

"`digits`" (gint : Read / Write) | The number of decimal places that are displayed in the value.
"`draw-value`" (gboolean : Read / Write) | Whether the current value is displayed as a string next to the slider.
"`value-pos`" (GtkPositionType : Read / Write) | The position in which the current value is displayed.

## Style Properties

"`slider-length`" (gint : Read) | Length of scale's slider.
"`value-spacing`" (gint : Read) | Space between value text and the slider/trough area.

## Signals

### The "format-value" signal

    gchar*      user_function                  (GtkScale *scale,
                                                gdouble arg1,
                                                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. Here's an example signal handler which displays a value 1.0 as with "-->1.0<--".

    static gchar*
    format_value_callback (GtkScale *scale,
                           gdouble   value)
    {
      return g_strdup_printf ("-->%0.*g<--",
                              gtk_scale_get_digits (scale), value);
    }

`scale` : | the object which received the signal.
`arg1` : |
`user_data` : | user data set when the signal handler was connected.
Returns : | allocated string representing `value`