GTK3 Conversion of Proportional Layout

proplayout.py

from gi.repository import Gtk
from gi.repository import Gdk
from gi.repository import cairo
from gi.repository import GObject


class ProportionalLayoutChild:
    def __init__(self,widget,left,right,top,bottom):
        self.widget=widget
        self.left=left
        self.right=right
        self.top=top
        self.bottom=bottom
        self.eventbox = None
        self.hidden = False

class ProportionalLayout(Gtk.Container):    
    '''
    An extension of Gtk.Container that supports sizing of children and positioning them
    in proportional (instead of pixel) terms
    '''
    __gtype_name__ = 'ProportionalLayout'
    def __init__(self,*children):
        super(ProportionalLayout, self).__init__()
        self.set_has_window(False)

        self.children=[]
        for ch in children:
            self.add_with_bg(*ch)
 
    def do_get_request_mode(self):
        return(Gtk.SizeRequestMode.CONSTANT_SIZE)
        
    def do_get_preferred_height_for_width(self, width):
        needed_req = [0,0]
        for ch in self.children:
            req = ch.widget.get_preferred_height_for_width(width)
            try:
                req[0] = int(req[0]/(ch.top-ch.bottom))
            except:
                pass
            try:
                req[1] = int(req[0]/(ch.top-ch.bottom))
            except:
                pass
            for i in range(2):
                if needed_req[i]<req[i]:
                    needed_req[i]=req[i]
        return tuple(needed_req)
        
    def do_get_preferred_width_for_height(self, height):
        needed_req = [0,0]
        for ch in self.children:
            req = ch.widget.get_preferred_width_for_height(height)
            try:
                req[0] = int(req[0]/(ch.right-ch.left))
            except:
                pass
            try:
                req[1] = int(req[1]/(ch.right-ch.left))
            except:
                pass
            for i in range(2):
                if needed_req[i]<req[i]:
                    needed_req[i]=req[i]
        return tuple(needed_req)

    def do_get_preferred_width(self):
        '''
        request the minimum size such that each child widget can fit within its specified proportions
        '''
        needed_req = [0,0]
        for ch in self.children:
            req = ch.widget.get_preferred_width()
            try:
                req[0] = int(req[0]/(ch.right-ch.left))
            except:
                pass
            try:
                req[1] = int(req[1]/(ch.right-ch.left))
            except:
                pass
            for i in range(2):
                if needed_req[i]<req[i]:
                    needed_req[i]=req[i]
        return tuple(needed_req)

    def do_get_preferred_height(self):
        '''
        request the minimum size such that each child widget can fit within its specified proportions
        '''
        needed_req = [0,0]
        for ch in self.children:
            req = ch.widget.get_preferred_width()
            try:
                req[0] = int(req[0]/(ch.top-ch.bottom))
            except:
                pass
            try:
                req[1] = int(req[0]/(ch.top-ch.bottom))
            except:
                pass
            for i in range(2):
                if needed_req[i]<req[i]:
                    needed_req[i]=req[i]
        return tuple(needed_req)

    def do_size_allocate (self, allocation):
        n = len(self.children)
        al = allocation
        for ch in self.children:
            widget = ch.eventbox if ch.eventbox else ch.widget
            left = ch.left
            right = ch.right
            if left == right: #centered
                w, wn = widget.get_preferred_width()
                w = 0
                left = int(al.x + left * al.width - w/2)
            elif left is not None and right is not None:
                w = int((right - left)*al.width)
                w = 0
                left = int(al.x + left * al.width)
            elif left is not None: #align right
                w, wn = widget.get_preferred_width()
                w = 0
                left = int(al.x + left * al.width)
            elif right is not None: #align left
                w, wn = widget.get_preferred_width()
                w = 0
                left = int(al.x + right * al.width - w)

            top = ch.top
            bottom = ch.bottom
            if top == bottom: #centered
                h, hn = widget.get_preferred_height()
                h = 0
                top = int(al.y + top * al.height - h/2)
            elif top is not None and bottom is not None:
                h = int((bottom - top)*al.height)
                h = 0
                top = int(al.y + top * al.height)
            elif top is not None: #align bottom
                h, hn = widget.get_preferred_height()
                h = 0
                top = int(al.y + top * al.height)
            elif bottom is not None: #align top
                h, hn = widget.get_preferred_height()
                h = 0
                top = int(al.x + bottom *al.height - h)

            a=cairo.RectangleInt(left,top,w,h)
            widget.size_allocate(a)

    def do_remove(self,child):
        i=0
        for ch in self.children:
            if ch.widget==child or ch.eventbox==child:
                if ch.eventbox:
                    ch.eventbox.remove(ch.widget)
                    ch.eventbox.unparent()
                else:
                    ch.widget.unparent()
                del self.children[i]
                return
            i+=1

    def add(self, widget, x_left, x_right, y_bottom, y_top):
        ch = ProportionalLayoutChild(widget, x_left, x_right, y_bottom, y_top)
        widget.set_parent(self)
        self.children.append(ch)
        self.queue_resize()

    def do_forall (self, include_internals, callback):
        try:
            for ch in self.children:
                if ch.eventbox:
                    callback (ch.eventbox)
                else:
                    callback (ch.widget)
        except AttributeError:
            print 'AttribError'

GObject.type_register(ProportionalLayout)


if __name__ == '__main__':
    proplayout = ProportionalLayout()
    proplayout.add(Gtk.Button('bottom-right'),0.5,1,0.5,1)

    box = Gtk.HBox()
    box.pack_start(Gtk.Button("test"), True, True, 0)
    box.pack_start(proplayout, True, True, 0)

    window = Gtk.Window ()
    window.add(box)
    window.set_size_request(600,300)
    window.connect('destroy', lambda window: Gtk.main_quit ())
    window.show_all()
    window.present ()

    Gtk.main ()

Converted from the original pygtk 2.0 class here: https://github.com/spillz/picty/blob/master/modules/picty/uitools/overlay_widgets.py