Package stripchart :: Module vgradezoom :: Class VGradeZoom
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Class VGradeZoom

VGradeScale --+
              |
             VGradeZoom


Widget that zooms a vertical graduated scale.

This class is an extension of the VGradeScale class, to make it an interactively zoomable widget. Interactions to change the zoom are executed by clicking with the left mouse button and then dragging with the left mouse button depressed, within the area of the widget.

Dragging upwards in the widget causes it to zoom in, whereas dragging downwards causes it to zoom out. The widget hilights yellow when it has the mouse focus to alert the user to the possibility of interaction. The maximum and minimum possible values that may be shown on the scale are the adjustment.upper and adjustment.lower values respectively. The widget will refuse to zoom outside of these values.

The sensitivity of the zoom is controlled by the instance variable called sensitivity. The default value of 0.006 should be quite good. The value shouldn't be very much greater than this, otherwise the scale becomes too jerky.

The interpretation of the gtk.Adjustment object used as the data model for this class is the same as for the VGradeScale class. The lower bound displayed by the widget is the value of the adjustment, whereas the upper bound is the value+page_size. Zooming interactively changes the page_size, and also possibly the value, of the adjustment. However, the scale will not change these values so that values outside the upper and lower values of the adjustment will be displayed.
Method Summary
  __init__(self, adjustment)
Initializes the widget.
    Inherited from VGradeScale
  __delattr__(self, name)
Delete attributes method.
  __setattr__(self, name, value)
Set attributes method.
  set_adjustment(self, adjustment)
Set the gtk.Adjustment used as the data model.
  set_bgcolor(self, color)
Set the background color of the component.

Instance Variable Summary
gtk.Adjustment adjustment: Data model for the component.
Tuple of (r, g, b) values in range 0 to 65535. bgcolor: Background color of the component.
Real number. sensitivity: Zoom sensitivity of the widget (around 0.006 is a good value).
gtk.DrawingArea widget: Read only pseudo-parent widget of the class.

Method Details

__init__(self, adjustment=None)
(Constructor)

Initializes the widget.
Parameters:
adjustment - Data model for the vertical range of the widget. If adjustment is None then a new, default gtk.Adjustment is created.
           (type=gtk.Adjustment)
Overrides:
stripchart.vgradescale.VGradeScale.__init__

Instance Variable Details

adjustment

Data model for the component.
Type:
gtk.Adjustment

bgcolor

Background color of the component.
Type:
Tuple of (r, g, b) values in range 0 to 65535.

sensitivity

Zoom sensitivity of the widget (around 0.006 is a good value).
Type:
Real number.

widget

Read only pseudo-parent widget of the class.
Type:
gtk.DrawingArea

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