Question

试图创建一个简单的绘画应用程序，我有一个按钮，当按下该按钮时，我希望清除画布，以便可以开始新的绘画。

我在tkinter界面中呈现了按钮，并且我在按钮中添加了与drawing_area.delete('all')命令等效的canvas.delete('all')命令，但是当我在画布上绘制并单击按钮时，似乎什么也没有发生。

不太确定我在哪里出错了，如果有人可以帮助我，那将非常好，我将应用程序的代码放在下面。

from tkinter import *
import tkinter.font
from PIL import Image, ImageTk

class PaintApp:

    # Stores current drawing tool used
    drawing_tool = "pencil"

    # Tracks whether left mouse is down
    left_but = "up"

    # x and y positions for drawing with pencil
    x_pos, y_pos = None, None


    # ---------- CATCH MOUSE UP ----------

    def left_but_down(self, event=None):
        self.left_but = "down"

        # Set x & y when mouse is clicked
        self.x1_line_pt = event.x
        self.y1_line_pt = event.y

    # ---------- CATCH MOUSE UP ----------

    def left_but_up(self, event=None):
        self.left_but = "up"

        # Reset the line
        self.x_pos = None
        self.y_pos = None

        # Set x & y when mouse is released
        self.x2_line_pt = event.x
        self.y2_line_pt = event.y

    # ---------- CATCH MOUSE MOVEMENT ----------

    def motion(self, event=None):

        if self.drawing_tool == "pencil":
            self.pencil_draw(event)

    # ---------- DRAW PENCIL ----------

    def pencil_draw(self, event=None):
        if self.left_but == "down":

            # Make sure x and y have a value
            if self.x_pos is not None and self.y_pos is not None:
                event.widget.create_line(self.x_pos, self.y_pos, event.x, event.y, smooth=TRUE)

            self.x_pos = event.x
            self.y_pos = event.y   

    def __init__(self, root):

        # Add buttons for Finishing and Getting a new Word combo

        drawing_area = Canvas(root, bd=2, highlightthickness=1, relief='ridge')
        drawing_area.pack(side = LEFT, fill="both", expand=True)
        drawing_area.bind("<Motion>", self.motion)
        drawing_area.bind("<ButtonPress-1>", self.left_but_down)
        drawing_area.bind("<ButtonRelease-1>", self.left_but_up)

        toolbar = Frame(root,bd=1,relief = RAISED)
        clearcanvas_img = Image.open("clearcanvas.png")
        clearcanvas_icon = ImageTk.PhotoImage(clearcanvas_img)
        clearcanvas_button = Button(toolbar, image=clearcanvas_icon, command = drawing_area.delete('all'))
        clearcanvas_button.image = clearcanvas_icon
        clearcanvas_button.pack (side = LEFT, padx=2, pady=2)
        toolbar.pack(side = TOP, fill= X)

root = Tk()
paint_app = PaintApp(root)
root.mainloop()

Answer 1

使用command=lambda: drawing_area.delete('all')将起作用。没有lambda，它只是在那里调用函数。但是您只需要在单击按钮时才能调用它。

Tkinter按钮未运行命令

1 个答案: