wxWidgets/wxPython/wx/lib/anchors.py

#----------------------------------------------------------------------
# Name:        wxPython.lib.anchors
# Purpose:     A class that provides an easy to use interface over layout
#              constraints for anchored layout.
#
# Author:      Riaan Booysen
#
# Created:     15-Dec-2000
# RCS-ID:      $Id$
# Copyright:   (c) 2000 by Total Control Software
# Licence:     wxWindows license
#----------------------------------------------------------------------
# 11/30/2003 - Jeff Grimmett (grimmtooth@softhome.net)
#
# o Updated for wx namespace
# o Tested with updated demo
# 

import  wx

class LayoutAnchors(wx.LayoutConstraints):
    """
    A class that implements Delphi's Anchors with wx.LayoutConstraints.

    Anchored sides maintain the distance from the edge of the control
    to the same edge of the parent.  When neither side is selected,
    the control keeps the same relative position to both sides.

    The current position and size of the control and it's parent is
    used when setting up the constraints. To change the size or
    position of an already anchored control, set the constraints to
    None, reposition or resize and reapply the anchors.

    Examples::

        Let's anchor the right and bottom edge of a control and
        resize it's parent.

        ctrl.SetConstraints(LayoutAnchors(ctrl, left=0, top=0, right=1, bottom=1))

        +=========+         +===================+
        | +-----+ |         |                   |
        | |     * |   ->    |                   |
        | +--*--+ |         |           +-----+ |
        +---------+         |           |     * |
                            |           +--*--+ |
                            +-------------------+
        * = anchored edge

        When anchored on both sides the control will stretch horizontally.

        ctrl.SetConstraints(LayoutAnchors(ctrl, 1, 0, 1, 1))

        +=========+         +===================+
        | +-----+ |         |                   |
        | *     * |   ->    |                   |
        | +--*--+ |         | +---------------+ |
        +---------+         | *     ctrl      * |
                            | +-------*-------+ |
                            +-------------------+
        * = anchored edge
        
    """
    def __init__(self, control, left=1, top=1, right=0, bottom=0):
        wx.LayoutConstraints.__init__(self)
        parent = control.GetParent()
        if not parent: return

        pPos, pSize = parent.GetPosition(), parent.GetClientSize()
        cPos, cSize = control.GetPosition(), control.GetSize()

        self.setConstraintSides(self.left, wx.Left, left,
                                self.right, wx.Right, right,
                                self.width, wx.Width, self.centreX,
                                cPos.x, cSize.width, pSize.width, parent)

        self.setConstraintSides(self.top, wx.Top, top,
                                self.bottom, wx.Bottom, bottom,
                                self.height, wx.Height, self.centreY,
                                cPos.y, cSize.height, pSize.height, parent)

    def setConstraintSides(self, side1, side1Edge, side1Anchor,
                                 side2, side2Edge, side2Anchor,
                                 size, sizeEdge, centre,
                                 cPos, cSize, pSize, parent):
        if side2Anchor:
            side2.SameAs(parent, side2Edge, pSize - (cPos + cSize))

        if side1Anchor:
            side1.SameAs(parent, side1Edge, cPos)

            if not side2Anchor:
                size.AsIs()
        else:
            size.AsIs()
            
            if not side2Anchor:
                centre.PercentOf(parent, sizeEdge,
                                 int(((cPos + cSize / 2.0) / pSize)*100))