Interface are used to specify the type of data structure which are exchanged between nodes. They are used to generate node widgets but also to do automatic conversion between different type of objects.

In this document we show:

• predefined_interfaces
• custom_interface_declaration

OpenAlea provides a set of common interfaces with associated widgets.

IFloat and IInt : Numeric value

IFloat and IInt interfaces support min and max specification. ex: IInt(0, 20)

IStr : String

IBool : Boolean

IFileStr and IDirStr : File or Directory names

You can specify a filename filter : IFileStr(“mtg (*.mtg)”)

IRGBColor : RGB Color

IEnumStr : Enumeration

You can specify the possible input values : IEnumStr([“Val1”, “Val2”])

ISequence : List

ITuple : Tuple

IDict : Dictionnary

IDateTime : Date and Time

If you need to use your own interface, you can declare it in your wralea.py file.

from openalea.core.interface import *
 
class IMyInterface(IInterface):
    """ My own interface """
    __metaclass__ = IInterfaceMetaClass
 
    # interface methods

You can also declare an interface widget which will be automatically associated with the interface.

Nota : Interface widget are registered in the platform by adding the following lines in the class declaration :

    __interface__ = IFloat   # Associated Interface class
    __metaclass__ = make_metaclass() # Registration by Metaclass 

from openalea.core import *
 
class IFloat(IInterface):
    """ Interface for Float object """
    __metaclass__ = IInterfaceMetaClass
    __pytype__ = types.FloatType
 
 
class IFloatWidget(IInterfaceWidget, QtGui.QWidget):
    """
    Float spin box widget
    """
 
    # Associate widget with the IFloat interface
    __interface__ = IFloat
    __metaclass__ = make_metaclass()
 
    def __init__(self, node, parent, parameter_str, interface):
        """
        @param parameter_str : the parameter key the widget is associated to
        @param interface : instance of interface object
        """
        QtGui.QWidget.__init__(self, parent)
        IInterfaceWidget.__init__(self, node, parent, parameter_str, interface)
 
        hboxlayout = QtGui.QHBoxLayout(self)
        self.spin = QtGui.QDoubleSpinBox (self)
        self.spin.setRange(interface.min, interface.max)
 
        hboxlayout.addWidget(self.spin)
 
        self.notify(None,None)
        self.connect(self.spin, QtCore.SIGNAL("valueChanged(double)"), self.valueChanged)
 
 
    def valueChanged(self, newval):
        self.node.set_input_by_key(self.param_str, newval)
 
    def notify(self, sender, event):
        """ Notification sent by node """
        try:
            v = float(self.node.get_input_by_key(self.param_str))
        except:
            v = 0.
 
        self.spin.setValue(v)