[英]Python Tkinter Canvas does not appear
你好我在python上使用Tkinter包有问题。 我想创建一个包含两个主要小部件的窗口,其中一个是一个画布,稍后将显示带有单元格的网格。 在初始化画布时,我使用“create_rectangle”来用所需的对象填充画布。 此外,当单击一个单元格(出于测试原因)时,画布应该在矩形区域中更改其颜色。 然而,当首先初始显示窗口时,不能看到任何对象(预期结果将只是白色矩形),并且仅当执行对画布的单击时,该区域根据需要改变其颜色。 在浏览互联网时,我尝试了pack() - 和create_rectangle() - 方法的几种变体。 这是代码:
from tkinter import *
from tkinter.ttk import *
import cells
GRID_WIDTH = 15
GRID_HEIGHT = 15
class Ui(Frame):
""" Class to represent the ui of conways game of life"""
def __init__(self, parent, grid):
self.parent = parent
self.grid = grid
Frame.__init__(self, parent)
self.__setup()
def __setup(self):
""" Method to setup the components of the ui """
self.parent.title("Conway's game of life")
self.pack()
#Setup a frame to hold control components
frame_cntrl = Frame(self)
frame_cntrl.pack(side = RIGHT, anchor="n")
self.__setup_cntrl_components(frame_cntrl)
#Setup a frame to hold the Grid
self.canvas = Canvas(self)
self.canvas.pack(side = LEFT)
self.__draw_grid()
self.canvas.bind("<Button-1>", self.__canvas_clicked)
def __setup_cntrl_components(self, parent):
""" Method to setup the control elements of the ui"""
#Setup a label for the generation
self.lb_generation = Label(parent, text="dummy")
self.lb_generation.pack(side = TOP)
#Setup a button for iteration
self.bt_iteration = Button(parent, text="Iterate")
self.bt_iteration.pack(side = TOP)
def __draw_cell(self, x, y):
""" Draws a cell on the canvas"""
width, height = self.canvas.winfo_width(), self.canvas.winfo_height()
color = "black" if self.grid.cell_alive(x, y) else "white"
x0 = width * x / self.grid.width + 1
x1 = width * (x + 1) / self.grid.width
y0 = height * y / self.grid.height + 1
y1 = height * (y + 1) / self.grid.height
self.canvas.create_rectangle(x0, y0, x1, y1, width=0, fill=color)
def __draw_grid(self):
""" Method to setup the grid itself"""
width, height = self.canvas.winfo_width(), self.canvas.winfo_height()
for i in range(0, self.grid.width):
for j in range(0, self.grid.height):
self.__draw_cell(i, j)
def __canvas_clicked(self, event):
""" Method for when the cell was clicked """
x, y, width, height = event.x, event.y, self.canvas.winfo_width(), self.canvas.winfo_height()
cell_x = int(x / width * self.grid.width)
cell_y = int(y / height * self.grid.height)
self.grid.switch_cell(cell_x, cell_y)
self.__draw_cell(cell_x, cell_y)
if __name__ == "__main__":
Ui(Tk(), cells.Grid(GRID_WIDTH, GRID_HEIGHT)).mainloop()
问题1 :
您的主要问题是,在实际显示画布之前, canvas.winfo_width()
和canvas.winfo_height()
不返回画布宽度和高度,而是返回值1
。
我建议您按如下方式创建画布:
# Define canvas and save dimensions
self.canvas_width = 300
self.canvas_height = 200
self.canvas = Canvas(self, width = self.canvas_width,
height = self.canvas_height)
然后,在您的代码中,替换每个实例:
width, height = self.canvas.winfo_width(), self.canvas.winfo_height()
同
width, height = self.canvas_width, self.canvas_height
问题2:
在创建每个单元格时,我认为您不需要将1添加到x0
和y0
。 相反,它应该是:
x0 = width * x / self.grid.width
x1 = width * (x + 1) / self.grid.width
y0 = height * y / self.grid.height
y1 = height * (y + 1) / self.grid.height
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