python计算圆周长、面积、球体体积并画出圆

输入半径，计算圆的周长、面积、球体体积，并画出这个圆。
拖动条、输入框和图像控件的数据保持一致！

fedora下测试通过

#https://github.com/robberphex/gtk-example-calcarea
from gi.repository import gtk, gdk, gdkpixbuf
from pil import image, imagedraw
from io import bytesio
from math import pi

class model:
    '''
    模型类
    存储半径，计算周长、面积、体积
    '''

    def __init__(self):
        self._radius = 0

    def setradius(self, radius):
        self._radius = float(radius)

    def getradius(self):
        return self._radius

    def getperimeter(self):
        return pi * self._radius * 2

    def getarea(self):
        return self._radius ** 2 * pi

    def getvolume(self):
        return 4 * pi * self._radius ** 3 / 3

class controller:
    '''
    控制器类
    控制视图和模型的更新
    '''

    def __init__(self, model):
        self.model = model
        self._observers = []

    def addobserver(self, observer):
        self._observers.append(observer)

    def setradius(self, radius):
        model.setradius(radius)
        self.notify()

    def notify(self):
        for observer in self._observers:
            observer.update()

class textview:
    '''
    文字视图类
    处理文本输入框的视图
    '''

    def __init__(self, model, rentry, pentry, aentry, ventry):
        '''
        :type model model
        '''
        self.model = model
        self.rentry = rentry
        self.pentry = pentry
        self.aentry = aentry
        self.ventry = ventry

    def update(self):
        self.rentry.set_text('%2.2f' % self.model.getradius())
        self.pentry.set_text('%2.2f' % self.model.getperimeter())
        self.aentry.set_text('%2.2f' % self.model.getarea())
        self.ventry.set_text('%2.2f' % self.model.getvolume())

class scaleview:
    '''
    拖动条视图
    处理拖动条的视图
    '''

    def __init__(self, model, scale):
        '''
        :type model model
        '''
        self.model = model
        self.scale = scale

    def update(self):
        self.scale.set_value(self.model.getradius())

class imageview:
    '''
    图像视图
    处理图像的视图
    '''

    @classmethod
    def imgtopixbuf(cls, img):
        '''
        :type img image
        '''
        buff = bytesio()
        img.save(buff, 'ppm')
        contents = buff.getvalue()
        buff.close()

        loader = gdkpixbuf.pixbufloader.new_with_type('pnm')
        loader.write(contents)
        pixbuf = loader.get_pixbuf()
        loader.close()
        return pixbuf

    @classmethod
    def ellipse(cls, radius):
        '''
        :type radius int
        '''
        image = image.new("rgba", (300, 300), "white")
        draw = imagedraw.draw(image)
        minor = 150 - radius
        major = 150 + radius
        draw.ellipse((minor, minor, major, major), outline='red')
        pixbuf = imageview.imgtopixbuf(image)
        return pixbuf

    def __init__(self, model, image):
        self.model = model
        self.image = image

    def update(self):
        radius = self.model.getradius()
        pixbuf = imageview.ellipse(radius)
        self.image.set_from_pixbuf(pixbuf)

class mainwindow(gtk.window):
    '''
    主窗口类
    负责整体界面的显示
    '''

    def textcallback(self, widget, controller):
        '''
        文本输入回调
        '''
        try:
            radius = float(widget.get_text())
            controller.setradius(radius)
        except valueerror as e:
            pass

    def scalecallback(self, widget, controller):
        '''
        拖动条回调
        '''
        radius = widget.get_value()
        controller.setradius(radius)

    def __init__(self):
        gtk.window.__init__(self, title="title")

        self.set_default_size(600, 400)
        self.set_position(gtk.windowposition.center)

        hbox = gtk.hbox(spacing=5)
        self.add(hbox)

        vbox = gtk.vbox(spacing=5)
        hbox.pack_start(vbox, true, true, 2)

        table = gtk.table.new(4, 2, false)
        vbox.pack_start(table, true, true, 2)

        label = gtk.label('半径：')
        table.attach_defaults(label, 0, 1, 0, 1)
        label = gtk.label('周长：')
        table.attach_defaults(label, 0, 1, 1, 2)
        label = gtk.label('面积：')
        table.attach_defaults(label, 0, 1, 2, 3)
        label = gtk.label('体积：')
        table.attach_defaults(label, 0, 1, 3, 4)

        self.radiusentry = gtk.entry.new()
        self.radiusentry.connect('changed', self.textcallback, controller)
        table.attach_defaults(self.radiusentry, 1, 2, 0, 1)
        self.perimeterentry = gtk.entry.new()
        self.perimeterentry.set_sensitive(false)
        self.perimeterentry.set_text('周长')
        table.attach_defaults(self.perimeterentry, 1, 2, 1, 2)
        self.areaentry = gtk.entry.new()
        self.areaentry.set_sensitive(false)
        self.areaentry.set_text('面积')
        table.attach_defaults(self.areaentry, 1, 2, 2, 3)
        self.volumeentry = gtk.entry.new()
        self.volumeentry.set_sensitive(false)
        self.volumeentry.set_text('体积')
        table.attach_defaults(self.volumeentry, 1, 2, 3, 4)

        self.scale = gtk.hscale.new_with_range(0, 100, 1)
        self.scale.connect('value-changed', self.scalecallback, controller)
        vbox.pack_start(self.scale, false, false, 2)

        pixbuf = gdkpixbuf.pixbuf.new(gdkpixbuf.colorspace.rgb, true, 8, 300, 300)
        pixbuf.fill(0xaaaaaaaa)
        self.image = gtk.image.new_from_pixbuf(pixbuf)
        hbox.pack_start(self.image, true, true, 2)

        self.connect('delete-event', gtk.main_quit)

model = model()
controller = controller(model)

if __name__ == '__main__':
    gdk.threads_init()
    gdk.threads_enter()
    win = mainwindow()

    iv = imageview(model, win.image)
    controller.addobserver(iv)

    tv = textview(model, win.radiusentry, win.perimeterentry, win.areaentry, win.volumeentry)
    controller.addobserver(tv)

    sv = scaleview(model, win.scale)
    controller.addobserver(sv)

    win.show_all()
    gtk.main()
    gdk.threads_leave()