Python 代码作为模块而不是 class
Python code works as module but not as class
我试图找出原因，但可能不知道正确的问题。我有一个项目，我正在尝试为我的汽车创建一个仪表板。问题是，当我尝试从另一个 class 制作一个 canvas 对象时，我的 GUI 启动但不显示任何内容。如果我在不要求 canvas 出现的情况下启动 GUI，则 GUI 工作并显示屏幕。我是 Python 的新手。我的版本是3.5
我的主程序：
from tkinter import*
from helperThingys import Helpers
root = Tk()
root.geometry("800x480")
bgLeft = Frame(root, bg="black", width=200, height=480)
bgLeft.pack_configure(fill=BOTH, expand=1, side=LEFT)
bgMiddle = Frame(root, bg="black", width=400, height=480)
bgMiddle.pack_configure(fill=BOTH, expand=1, side=LEFT)
bgRight = Frame(root, bg="black", width=200, height=480)
bgRight.pack_configure(fill=BOTH, expand=1, side=LEFT)
# These are really gif images read to labels to be able to grid them
# now just plain text labels for convenience.
label_4hi = Label(bgLeft, text="ok", bg="green")
label_4lo = Label(bgLeft, text="ok", bg="green")
label_lock = Label(bgLeft, text="ok", bg="green")
label_batt = Label(bgMiddle, text="ok", bg="red")
label_fuelF = Label(bgLeft, text="ok", bg="orange")
label_glow = Label(bgLeft, text="ok", bg="yellow")
label_hb = Label(bgMiddle, text="ok", bg="blue")
label_indL = Label(bgMiddle, text="ok", bg="green")
label_indR = Label(bgMiddle, text="ok", bg="green")
label_lowFuel = Label(bgLeft, text="ok", bg="red")
label_lowOil = Label(bgLeft, text="ok", bg="red")
label_park = Label(bgMiddle, text="ok", bg="red")
label_pwrS = Label(bgLeft, text="ok", bg="red")
label_rFog = Label(bgLeft, text="ok", bg="orange")
label_temp = Label(bgLeft, text="ok", bg="red")
label_gauge = Label(bgMiddle, text="ok", bg="red")
# Middle frame
bgMiddle.rowconfigure(0, minsize=46, weight=1)
bgMiddle.rowconfigure(1, minsize=217, weight=5)
bgMiddle.rowconfigure(2, minsize=217, weight=5)
bgMiddle.columnconfigure(0, minsize=80)
bgMiddle.columnconfigure(1, minsize=80)
bgMiddle.columnconfigure(2, minsize=80)
bgMiddle.columnconfigure(3, minsize=80)
bgMiddle.columnconfigure(4, minsize=80)
label_indL.grid(row=0, column=0, sticky=E+N+W)
label_hb.grid(row=0, column=1, sticky=E+N+S+W)
label_park.grid(row=0, column=2, sticky=E+N+S+W)
label_batt.grid(row=0, column=3, sticky=E+N+S+W)
label_indR.grid(row=0, column=4, sticky=E+N+S+W)
# Left frame
bgLeft.rowconfigure(0, minsize=46, weight=1)
bgLeft.rowconfigure(1, minsize=46, weight=1)
bgLeft.rowconfigure(2, minsize=46, weight=1)
bgLeft.rowconfigure(3, minsize=46, weight=1)
bgLeft.rowconfigure(4, minsize=46, weight=1)
bgLeft.columnconfigure(0, minsize=100)
bgLeft.columnconfigure(1, minsize=100)
label_4hi.grid(row=0, column=0, sticky=E+N+S+W)
label_4lo.grid(row=0, column=1, sticky=E+N+S+W)
label_lock.grid(row=1, column=0, sticky=E+N+S+W)
label_pwrS.grid(row=1, column=1, sticky=E+N+S+W)
label_rFog.grid(row=2, column=0, sticky=E+N+S+W)
label_lowFuel.grid(row=2, column=1, sticky=E+N+S+W)
label_lowOil.grid(row=3, column=0, sticky=E+N+S+W)
label_temp.grid(row=3, column=1, sticky=E+N+S+W)
label_fuelF.grid(row=4, column=0, sticky=E+N+S+W)
label_glow.grid(row=4, column=1, sticky=E+N+S+W)
# Middle frame
speedo = helpers.Gauge()
speedo.makeGauge(bgMiddle, 150, "speed")
speedo.grid(row=1, columnspan=5, sticky=E+N+S+W)
#label_gauge.grid(row=1, columnspan=5, sticky=E+N+S+W)
# Right Frame
#oilPres = Gauge(bgRight, 150, "oilPres")
root.mainloop()
这是来自 helperThingys 包的 'helpers.py'。
from tkinter import Canvas
class Gauge(Canvas):
def __init__(self):
Canvas.__init__(self)
pass
def makeGauge(self, window, value, gaugeType):
if gaugeType == "speed":
baseCanvas = Canvas(window, bg="black", width=400, height=217,
highlightthickness=0)
baseCanvas.create_arc([10, 5, 390, 395], start=0, extent=180,
fill="white")
return baseCanvas
我使用 canvases 作为仪表的背景。奇怪的是，这个 'helpers.py' 工作并为我的 GUI 创建了 canvases，但它不是 class 而是一个模块：
def makeGauge(self, window, value, gaugeType):
if gaugeType == "speed":
baseCanvas = Canvas(window, bg="black", width=400, height=217,
highlightthickness=0)
baseCanvas.create_arc([10, 5, 390, 395], start=0, extent=180,
fill="white")
return baseCanvas
... 等等（该模块当时与 GUI 在同一个包中）。这就是为什么我知道 canvases 与 GUI 一起工作。在 class 中使用它们时我做错了什么？
感谢您的回答。
你的问题是 Gauge 都是 Canvas 的子class 并且 创建了一个或多个其他 canvas es（奇怪的是，其他 window 的 child）。
当您调用 makeGauge 时，这将创建第二个 canvas 和 returns。但是，您不保存引用，并且您从不在这一秒 canvas 上调用 pack、place 或 grid，因此它永远不会显示。
我不知道你打算用这两个 canvas 做什么，但我猜你真的只想要一个。我建议像这样创建 class，在创建 canvas 时传递所有参数，这样您就可以一步创建仪表：
class Gauge(Canvas):
def __init__(self, parent, value, gaugeType):
Canvas.__init__(self, parent)
self.makeGauge(value, gaugeType)
def makeGauge(self, value, gaugeType):
if gaugeType == "speed":
self.configure(bg="black", width=400, height=217,
highlightthickness=0)
self.create_arc([10, 5, 390, 395], start=0, extent=180,
fill="white")
elif gaugeType == "rpm":
...
speedo = Gauge(bgMiddle, 150, "speed")
speedo.grid(...)
如果你想保留两个 canvas，或者你决定让 Gauge 继承自其他东西，你需要保存 makeGauge 返回的引用，并且然后将其添加到显示中：
gauge = speedo.makeGauge(bgMiddle, 150, "speed")
gauge.grid(row=1, columnspan=5, sticky=E+N+S+W)
我试图找出原因，但可能不知道正确的问题。我有一个项目，我正在尝试为我的汽车创建一个仪表板。问题是，当我尝试从另一个 class 制作一个 canvas 对象时，我的 GUI 启动但不显示任何内容。如果我在不要求 canvas 出现的情况下启动 GUI，则 GUI 工作并显示屏幕。我是 Python 的新手。我的版本是3.5
我的主程序：
from tkinter import*
from helperThingys import Helpers
root = Tk()
root.geometry("800x480")
bgLeft = Frame(root, bg="black", width=200, height=480)
bgLeft.pack_configure(fill=BOTH, expand=1, side=LEFT)
bgMiddle = Frame(root, bg="black", width=400, height=480)
bgMiddle.pack_configure(fill=BOTH, expand=1, side=LEFT)
bgRight = Frame(root, bg="black", width=200, height=480)
bgRight.pack_configure(fill=BOTH, expand=1, side=LEFT)
# These are really gif images read to labels to be able to grid them
# now just plain text labels for convenience.
label_4hi = Label(bgLeft, text="ok", bg="green")
label_4lo = Label(bgLeft, text="ok", bg="green")
label_lock = Label(bgLeft, text="ok", bg="green")
label_batt = Label(bgMiddle, text="ok", bg="red")
label_fuelF = Label(bgLeft, text="ok", bg="orange")
label_glow = Label(bgLeft, text="ok", bg="yellow")
label_hb = Label(bgMiddle, text="ok", bg="blue")
label_indL = Label(bgMiddle, text="ok", bg="green")
label_indR = Label(bgMiddle, text="ok", bg="green")
label_lowFuel = Label(bgLeft, text="ok", bg="red")
label_lowOil = Label(bgLeft, text="ok", bg="red")
label_park = Label(bgMiddle, text="ok", bg="red")
label_pwrS = Label(bgLeft, text="ok", bg="red")
label_rFog = Label(bgLeft, text="ok", bg="orange")
label_temp = Label(bgLeft, text="ok", bg="red")
label_gauge = Label(bgMiddle, text="ok", bg="red")
# Middle frame
bgMiddle.rowconfigure(0, minsize=46, weight=1)
bgMiddle.rowconfigure(1, minsize=217, weight=5)
bgMiddle.rowconfigure(2, minsize=217, weight=5)
bgMiddle.columnconfigure(0, minsize=80)
bgMiddle.columnconfigure(1, minsize=80)
bgMiddle.columnconfigure(2, minsize=80)
bgMiddle.columnconfigure(3, minsize=80)
bgMiddle.columnconfigure(4, minsize=80)
label_indL.grid(row=0, column=0, sticky=E+N+W)
label_hb.grid(row=0, column=1, sticky=E+N+S+W)
label_park.grid(row=0, column=2, sticky=E+N+S+W)
label_batt.grid(row=0, column=3, sticky=E+N+S+W)
label_indR.grid(row=0, column=4, sticky=E+N+S+W)
# Left frame
bgLeft.rowconfigure(0, minsize=46, weight=1)
bgLeft.rowconfigure(1, minsize=46, weight=1)
bgLeft.rowconfigure(2, minsize=46, weight=1)
bgLeft.rowconfigure(3, minsize=46, weight=1)
bgLeft.rowconfigure(4, minsize=46, weight=1)
bgLeft.columnconfigure(0, minsize=100)
bgLeft.columnconfigure(1, minsize=100)
label_4hi.grid(row=0, column=0, sticky=E+N+S+W)
label_4lo.grid(row=0, column=1, sticky=E+N+S+W)
label_lock.grid(row=1, column=0, sticky=E+N+S+W)
label_pwrS.grid(row=1, column=1, sticky=E+N+S+W)
label_rFog.grid(row=2, column=0, sticky=E+N+S+W)
label_lowFuel.grid(row=2, column=1, sticky=E+N+S+W)
label_lowOil.grid(row=3, column=0, sticky=E+N+S+W)
label_temp.grid(row=3, column=1, sticky=E+N+S+W)
label_fuelF.grid(row=4, column=0, sticky=E+N+S+W)
label_glow.grid(row=4, column=1, sticky=E+N+S+W)
# Middle frame
speedo = helpers.Gauge()
speedo.makeGauge(bgMiddle, 150, "speed")
speedo.grid(row=1, columnspan=5, sticky=E+N+S+W)
#label_gauge.grid(row=1, columnspan=5, sticky=E+N+S+W)
# Right Frame
#oilPres = Gauge(bgRight, 150, "oilPres")
root.mainloop()
这是来自 helperThingys 包的 'helpers.py'。
from tkinter import Canvas
class Gauge(Canvas):
def __init__(self):
Canvas.__init__(self)
pass
def makeGauge(self, window, value, gaugeType):
if gaugeType == "speed":
baseCanvas = Canvas(window, bg="black", width=400, height=217,
highlightthickness=0)
baseCanvas.create_arc([10, 5, 390, 395], start=0, extent=180,
fill="white")
return baseCanvas
我使用 canvases 作为仪表的背景。奇怪的是，这个 'helpers.py' 工作并为我的 GUI 创建了 canvases，但它不是 class 而是一个模块：
def makeGauge(self, window, value, gaugeType):
if gaugeType == "speed":
baseCanvas = Canvas(window, bg="black", width=400, height=217,
highlightthickness=0)
baseCanvas.create_arc([10, 5, 390, 395], start=0, extent=180,
fill="white")
return baseCanvas
... 等等（该模块当时与 GUI 在同一个包中）。这就是为什么我知道 canvases 与 GUI 一起工作。在 class 中使用它们时我做错了什么？
感谢您的回答。
你的问题是 Gauge 都是 Canvas 的子class 并且 创建了一个或多个其他 canvas es（奇怪的是，其他 window 的 child）。
当您调用 makeGauge 时，这将创建第二个 canvas 和 returns。但是，您不保存引用，并且您从不在这一秒 canvas 上调用 pack、place 或 grid，因此它永远不会显示。
我不知道你打算用这两个 canvas 做什么，但我猜你真的只想要一个。我建议像这样创建 class，在创建 canvas 时传递所有参数，这样您就可以一步创建仪表：
class Gauge(Canvas):
def __init__(self, parent, value, gaugeType):
Canvas.__init__(self, parent)
self.makeGauge(value, gaugeType)
def makeGauge(self, value, gaugeType):
if gaugeType == "speed":
self.configure(bg="black", width=400, height=217,
highlightthickness=0)
self.create_arc([10, 5, 390, 395], start=0, extent=180,
fill="white")
elif gaugeType == "rpm":
...
speedo = Gauge(bgMiddle, 150, "speed")
speedo.grid(...)
如果你想保留两个 canvas，或者你决定让 Gauge 继承自其他东西，你需要保存 makeGauge 返回的引用，并且然后将其添加到显示中：
gauge = speedo.makeGauge(bgMiddle, 150, "speed")
gauge.grid(row=1, columnspan=5, sticky=E+N+S+W)