如何设置Python tkinter canvas元素的z索引? [英] How do I set the z index of an Python tkinter canvas element?

问题描述

如何在初次启动画布时设置tkinter画布元素(圆形，矩形)的z-index?或者我可以在绘制例如时直接设置z-index一个圆圈?不幸的是，我对 canvas.tag_lower("tag_name")所做的工作不多.我以为这个命令会将标记的所有元素都移回一级-是这样吗?

how can I set the z-index of tkinter canvas elements (circle, rectangle) on initial startup of the canvas? Or can I set a z-index directly when drawing e.g. a circle? Unfortunately I could not do much with canvas.tag_lower("tag_name"). I thought this command moves all elements of a tag one level back - is that so?

class CanvasGui(tk.Canvas):

    def __init__(self, master):
        super().__init__(master, bg="#FFF", highlightthickness=0, borderwidth=0)
        self.pack(fill="both", expand=True)
        self.setCanvasLayers()

    def setCanvasLayers(self):
        self.tag_lower("highlightGridPoint")
        self.tag_lower("grid")

我认为，标记为"highlightGridPoint"的元素现在应该位于最远的背景中，标记为"grid"的元素应该位于最远的背景中.但是，如果我运行该程序，事实并非如此……

In my opinion, the elements with the tag "highlightGridPoint" should now be in the farthest background and the elements with the tag "grid" in the foreground. But if I run the program, it's not so...

推荐答案

您必须先创建标签，然后才能设置标签的顺序.您的代码会升高和降低尚不存在的标签.

You can't set the ordering of a tag until after the tag has been created. Your code raises and lowers tags that don't yet exist.

您可以通过注意到以下代码在行为上的差异来看到这一点:

You can see this by noticing the difference in behavior between this code:

canvas.setCanvasLayers()
canvas.create_rectangle(10,10,50,50, fill="red", tags=("red",))
canvas.create_rectangle(20,20,60,60, fill="green", tags=("green",))

...以及此代码:

canvas.create_rectangle(10,10,50,50, fill="red", tags=("red",))
canvas.create_rectangle(20,20,60,60, fill="green", tags=("green",))
canvas.setCanvasLayers()

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