用鼠标移动tkinter画布

Question

用鼠标移动tkinter画布

pythonuser-interfacetkintertkinter-canvas

9

我想通过鼠标点击（按住）+鼠标移动来移动整个tkinter Canvas。我尝试使用canvas.move，但不幸的是它不起作用。

如何在整个画布中滚动？ (不是移动画布的每个元素，而是滚动画布的显示区域)

import Tkinter as Tk

oldx = 0
oldy = 0

def oldxyset(event):
    global oldx, oldy
    oldx = event.x
    oldy = event.y

def callback(event):
    # How to move the whole canvas here?
    print oldx - event.x, oldy - event.y

root = Tk.Tk()

c = Tk.Canvas(root, width=400, height=400, bg='white')
o = c.create_oval(150, 10, 100, 60, fill='red')
c.pack()

c.bind("<ButtonPress-1>", oldxyset)
c.bind("<B1-Motion>", callback)

root.mainloop()

- Basj

1个回答

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- Bryan Oakley · Accepted Answer

Canvas提供了鼠标滚动的内置支持，通过使用scan_mark和scan_dragto方法。前者记录了您点击鼠标的位置，后者滚动相应数量的像素。

注意: gain属性告诉scan_moveto每移动一个鼠标像素需要移动多少像素。默认值是10，因此如果您想要鼠标光标与画布之间的1:1对应关系，则需要将此值设置为1(如示例所示)。

以下是一个例子:

import Tkinter as tk
import random

class Example(tk.Frame):
    def __init__(self, root):
        tk.Frame.__init__(self, root)
        self.canvas = tk.Canvas(self, width=400, height=400, background="bisque")
        self.xsb = tk.Scrollbar(self, orient="horizontal", command=self.canvas.xview)
        self.ysb = tk.Scrollbar(self, orient="vertical", command=self.canvas.yview)
        self.canvas.configure(yscrollcommand=self.ysb.set, xscrollcommand=self.xsb.set)
        self.canvas.configure(scrollregion=(0,0,1000,1000))

        self.xsb.grid(row=1, column=0, sticky="ew")
        self.ysb.grid(row=0, column=1, sticky="ns")
        self.canvas.grid(row=0, column=0, sticky="nsew")
        self.grid_rowconfigure(0, weight=1)
        self.grid_columnconfigure(0, weight=1)

        for n in range(50):
            x0 = random.randint(0, 900)
            y0 = random.randint(50, 900)
            x1 = x0 + random.randint(50, 100)
            y1 = y0 + random.randint(50,100)
            color = ("red", "orange", "yellow", "green", "blue")[random.randint(0,4)]
            self.canvas.create_rectangle(x0,y0,x1,y1, outline="black", fill=color)
        self.canvas.create_text(50,10, anchor="nw", 
                                text="Click and drag to move the canvas")

        # This is what enables scrolling with the mouse:
        self.canvas.bind("<ButtonPress-1>", self.scroll_start)
        self.canvas.bind("<B1-Motion>", self.scroll_move)

    def scroll_start(self, event):
        self.canvas.scan_mark(event.x, event.y)

    def scroll_move(self, event):
        self.canvas.scan_dragto(event.x, event.y, gain=1)


if __name__ == "__main__":
    root = tk.Tk()
    Example(root).pack(fill="both", expand=True)
    root.mainloop()