如何使用Tkinter移动Canvas图像？

Question

大家好，我正在写一段代码，想用Python的Tkinter库在画布上移动一张图片。可是这让我遇到了问题。虽然图片能显示出来，但就是动不了。

from Tkinter import *
root = Tk()
root.title("Click me!")
def next_image(event):
    global toggle_flag
    global x, y, photo1
    # display photo2, move to right, y stays same
    canvas1.create_image(x+10, y, image=photo1)
    canvas1.create_image(x+20, y, image=photo1)           
    canvas1.create_image(x+30, y, image=photo1)
    canvas1.create_image(x+40, y, image=photo1)
    canvas1.create_image(x+50, y, image=photo1)
    canvas1.create_image(x+60, y, image=photo1)
    canvas1.create_image(x+70, y, image=photo1)
    canvas1.create_image(x+100, y, image=photo1)

image1 = "C:\Python26\Lib\site-packages\pygame\examples\data\ADN_animation.gif"   #use some random gif
photo1 = PhotoImage(file=image1)
# make canvas the size of image1/photo1
width1 = photo1.width()
height1 = photo1.height()
canvas1 = Canvas(width=width1, height=height1)
canvas1.pack()
# display photo1, x, y is center (anchor=CENTER is default)
x = (width1)/2.0
y = (height1)/2.0
canvas1.create_image(x, y, image=photo1)
canvas1.bind('<Button-1>', next_image)  # bind left mouse click
root.mainloop() 

Answer 1

Canvas 提供了一个叫做 move 的方法。这个方法需要几个参数：你想移动的对象、从之前位置往右移动的距离（x方向），以及往下移动的距离（y方向）。

你需要保存 create_image 的返回值，这样才能把它传给 move 方法。

另外，要确保画布是可以扩展的（在下面的代码中用 pack(expand=1, fill=BOTH) 来实现）。

from Tkinter import *

root = Tk()

def next_image(event):
    canvas1.move(item, 10, 0) # <--- Use Canvas.move method.

image1 = r"C:\Python26\Lib\site-packages\pygame\examples\data\ADN_animation.gif"
photo1 = PhotoImage(file=image1)
width1 = photo1.width()
height1 = photo1.height()
canvas1 = Canvas(width=width1, height=height1)
canvas1.pack(expand=1, fill=BOTH) # <--- Make your canvas expandable.
x = (width1)/2.0
y = (height1)/2.0
item = canvas1.create_image(x, y, image=photo1) # <--- Save the return value of the create_* method.
canvas1.bind('<Button-1>', next_image)
root.mainloop() 

---

根据评论的更新

使用 after 方法，你可以安排一个函数在指定的时间后被调用。

def next_image(event=None):
    canvas1.move(item, 10, 0)
    canvas1.after(100, next_image) # Call this function after 100 ms.