gtk.Adjustment
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gtk.Adjustment

gtk.Adjustment — an object representing an adjustable bounded value

Synopsis

class gtk.Adjustment(gtk.Object):
    gtk.Adjustment(value=0, lower=0, upper=0, step_incr=0, page_incr=0, page_size=0)
    def set_all(value, lower, upper, step_increment, page_increment, page_size)
    def changed()
    def value_changed()
    def clamp_page(lower, upper)
    def get_value()
    def set_value(value)

Ancestry

+-- gobject.GObject
  +-- gtk.Object
    +-- gtk.Adjustment

gtk.Adjustment Properties

gtk.Object Properties

Note

These properties are available in GTK+ 2.4 and above. The GTK+ version is contained in the 3-tuple gtk.gtk_version.

"lower"Read-WriteThe minimum value of the adjustment. (float)
"page-increment"Read-WriteThe page increment of the adjustment. (float)
"page-size"Read-WriteThe page size of the adjustment. (float)
"step-increment"Read-WriteThe step increment of the adjustment. (float)
"upper"Read-WriteThe maximum value of the adjustment. (float)
"value"Read-WriteThe value of the adjustment. (float)

Attributes

"value"Read-Writethe current value (float)
"lower"Read-Writethe minimum value (float)
"upper"Read-Writethe maximum value (float)
"step_increment"Read-Writethe increment to use to make minor changes to the value. In a gtk.Scrollbar 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. (float)
"page_increment"Read-Writethe increment to use to make major changes to the value. In a gtk.Scrollbar this increment is used when the mouse is clicked in the trough, to scroll by a large amount. (float)
"page_size"Read-Writea widget specific size. In a gtk.Scrollbar this is the size of the area which is currently visible. (float)

gtk.Adjustment Signal Prototypes

gobject.GObject Signal Prototypes

gtk.Object Signal Prototypes

"changed" def callback(adjustment, user_param1, ...)
"value-changed" def callback(adjustment, user_param1, ...)

Description

The gtk.Adjustment object contains a value which has an associated lower and upper bound, together with step and page increments, and a page size. It is used in conjunction with several PyGTK widgets, including gtk.SpinButton, gtk.Viewport, and gtk.Range (which is a base class for gtk.HScrollbar, gtk.VScrollbar, gtk.HScale, and gtk.VScale).

A gtk.Adjustment can be shared by multiple widgets. The gtk.Adjustment object does not update the value itself. Instead it is left up to the associated widget(s) that use the gtk.Adjustment to control the value.

The widget using the gtk.Adjustment typically calls the value_changed() or changed() methods after changing the value or its bounds. This results in the emission of the "value_changed" or "changed" signal respectively.

A gtk.Adjustment object contains several attributes that provide access to its value and bounds:

  • value
  • lower
  • upper
  • step_increment
  • page_increment
  • page_size

The attribute values can be retrieved and set similar to:

  adjustment.upper = 25.0
  lower = adjustment.lower

Constructor

    gtk.Adjustment(value=0, lower=0, upper=0, step_incr=0, page_incr=0, page_size=0)
value :the initial value.
lower :the minimum value.
upper :the maximum value.
step_incr :the step increment.
page_incr :the page increment.
page_size :the page size.
Returns :a new gtk.Adjustment object

gtk.Adjustment() creates a new gtk.Adjustment object with the specified attributes. Any attributes not specified are set to 0.0 by default.

Methods

gtk.Adjustment.set_all

    def set_all(value, lower, upper, step_increment, page_increment, page_size)
value :the new value.
lower :the new minimum value.
upper :the new maximum value.
step_increment :the new step increment.
page_increment :the new page increment.
page_size :the new page size.

The set_all() method sets the attributes of the adjustment to the specified values.

gtk.Adjustment.changed

    def changed()

The changed() method emits a "changed" signal from the adjustment. This must typically be called if any of the adjustment attributes other than value has changed so that the widget(s) using the adjustment can reflect the changes. Applications usually will not need to use this method since setting the attributes directly will automatically invoke this method.

gtk.Adjustment.value_changed

    def value_changed()

The value_changed() method emits a "value_changed" signal from the adjustment. This must typically be called after the value attribute of the adjustment has changed. Applications usually will not need to use this method since setting the attribute directly will automatically invoke this method as will using the set_value() method.

gtk.Adjustment.clamp_page

    def clamp_page(lower, upper)
lower :the lower value
upper :the upper value

The clamp_page() method updates the adjustment 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.

gtk.Adjustment.get_value

    def get_value()
Returns :The current value of the adjustment.

The get_value() method gets the current value of the adjustment.

gtk.Adjustment.set_value

    def set_value(value)
value :the new value

The set_value() method sets the value of the adjustment to the specified value.

Signals

The "changed" gtk.Adjustment Signal

    def callback(adjustment, user_param1, ...)
adjustment :the object that received the signal
user_param1 :the first user parameter (if any) specified with the connect() method
... :additional user parameters (if any)

The "changed" signal is emitted when one (or more) of the adjustment attributes (except the value attribute) has changed.

The "value-changed" gtk.Adjustment Signal

    def callback(adjustment, user_param1, ...)
adjustment :the object that received the signal
user_param1 :the first user parameter (if any) specified with the connect() method
... :additional user parameters (if any)

The "value-changed" signal is emitted when the adjustment value attribute has changed.

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