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

复制代码 代码如下:

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()