scan_mark
画布通过和scan_dragto
方法内置了对鼠标滚动的支持。前者记住您单击鼠标的位置,后者将窗口滚动适当数量的像素。
注意:该gain
属性告诉scan_moveto
鼠标移动的每个像素要移动多少像素。默认情况下为 10,因此如果您希望光标和画布之间的相关性为 1:1,则需要将此值设置为 1(如示例所示)。
这是一个例子:
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()