请运行以下代码以获取如下内容：

基本上，我已经建立了一个Gtk.DrawingArea，它位于一个Gtk.Viewport内部，它也位于一个Gtk.Scrolledwindow中。在上述的DrawingArea中，我绘制图像，并使用2个按钮可以缩放该图像。

# -*- encoding: utf-8 -*-

import gi
gi.require_version('Gtk','3.0')
from gi.repository import Gtk
from gi.repository import Gdk
from gi.repository import GdkPixbuf


class MyWindow(Gtk.Window):

    def __init__(self):

        Gtk.Window.__init__(self,title="DrawingTool")
        self.set_default_size(800,600)

        # The ratio
        self.ratio = 1.

        # Image
        filename = "image.jpg"
        self.original_image = GdkPixbuf.Pixbuf.new_from_file(filename)
        self.displayed_image = GdkPixbuf.Pixbuf.new_from_file(filename)

        box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL,spacing=6)
        # zoom buttons
        self.button_zoom_in = Gtk.Button(label="zoom-In")
        self.button_zoom_out = Gtk.Button(label="zoom-Out")      
        # |Scrolledwindow
        # |-> Viewport
        # |--> DrawingArea 
        scrolledwindow = Gtk.Scrolledwindow()
        viewport = Gtk.Viewport()
        self.drawing_area = Gtk.DrawingArea()
        self.drawing_area.set_size_request(
                              self.displayed_image.get_width(),self.displayed_image.get_height())
        self.drawing_area.set_events(Gdk.EventMask.ALL_EVENTS_MASK)

        # Pack
        viewport.add(self.drawing_area)
        scrolledwindow.add(viewport)
        box.pack_start(self.button_zoom_in,False,True,0)
        box.pack_start(self.button_zoom_out,0)
        box.pack_start(scrolledwindow,0)
        self.add(box)

        # Connect
        self.connect("destroy",Gtk.main_quit)
        self.button_zoom_in.connect("clicked",self.on_button_zoom_in_clicked)
        self.button_zoom_out.connect("clicked",self.on_button_zoom_out_clicked)
        self.drawing_area.connect("enter-notify-event",self.on_drawing_area_mouse_enter)
        self.drawing_area.connect("leave-notify-event",self.on_drawing_area_mouse_leave)
        self.drawing_area.connect("motion-notify-event",self.on_drawing_area_mouse_motion)
        self.drawing_area.connect("draw",self.on_drawing_area_draw)

        self.show_all()

    def on_button_zoom_in_clicked(self,widget):
        self.ratio += 0.1
        self.scale_image()
        self.drawing_area.queue_draw()

    def on_button_zoom_out_clicked(self,widget):
        self.ratio -= 0.1
        self.scale_image()
        self.drawing_area.queue_draw()

    def scale_image(self):
        self.displayed_image = self.original_image.scale_simple(self.original_image.get_width() * self.ratio,self.original_image.get_height() * self.ratio,2)

    def on_drawing_area_draw(self,drawable,cairo_context):
        pixbuf = self.displayed_image           
        self.drawing_area.set_size_request(pixbuf.get_width(),pixbuf.get_height())
        Gdk.cairo_set_source_pixbuf(cairo_context,pixbuf,0)
        cairo_context.paint()

    def on_drawing_area_mouse_enter(self,widget,event):
        print("In - DrawingArea")

    def on_drawing_area_mouse_leave(self,event):
        print("Out - DrawingArea")

    def on_drawing_area_mouse_motion(self,event):

        (x,y) = int(event.x),int(event.y)
        offset = ( (y*self.displayed_image.get_rowstride()) + 
                   (x*self.displayed_image.get_n_channels()) )
        pixel_intensity = self.displayed_image.get_pixels()[offset]
        print("(" + str(x) + "," + str(y) + ") = " + str(pixel_intensity))



MyWindow()
Gtk.main()

运行该应用程序。我还设置了一些回调，因此，当您将鼠标指针悬停在图像上时，您会知道：

i）当您输入DrawingArea

ii）离开绘图区时

iii）在DrawingArea处的（x，y）和图像像素强度

我面临的问题是，当您缩小足够多的时间时，图像将如下所示：

但是，“鼠标进入”和“鼠标离开”信号以及“鼠标运动”信号都被发送，就像DrawingArea仍具有创建时的尺寸一样。请将鼠标悬停在图像上方和图像外部但在DrawingArea内部，以查看终端中的输出。

我希望将信号悬停在图像之外时不要发送自己。也就是说，如果可能，请将DrawingArea大小调整为显示的图像大小。