用鼠标移动和缩放 tkinter 画布 [英] Move and zoom a tkinter canvas with mouse

问题描述

这里是我想要的描述:在 tkinter 画布中绘制一组几何对象(此处为矩形)，然后可以使用鼠标探索该画布.单击并拖动移动画布，滚动放大和缩小.

Here a description of what I would like : Draw a collection of geometric objects (here, rectangles) in a tkinter canvas, and beeing abble to explore this canvas using mouse. Click and drag move the canvas, scrolling zooms in and zooms out.

使用这个主题，我找到了点击和拖动部分:使用鼠标移动 tkinter 画布用鼠标

Using this topic, I found the click and drag part : Move a tkinter canvas with Mouse with-mouse

我设法为滚动缩放写了一些东西.移动和缩放都可以分别很好地工作.

I managed to write something for scrolling zoom. Both moving and zooming work well separatly.

问题:如果我移动然后放大，放大的焦点不再是光标的位置.

The problem : If I move and then zoom in, the focus of the zoom is not anymore the position of the cursor.

有什么建议吗?

这里有一段代码要测试

[edit : 现在应该适用于 linux 和 windows]

[edit : should now works for linux and windows]

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)

        #Plot some rectangles
        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, activefill="black", tags=n)
        self.canvas.create_text(50,10, anchor="nw", text="Click and drag to move the canvas
Scroll to zoom.")

        # This is what enables using the mouse:
        self.canvas.bind("<ButtonPress-1>", self.move_start)
        self.canvas.bind("<B1-Motion>", self.move_move)
        #linux scroll
        self.canvas.bind("<Button-4>", self.zoomerP)
        self.canvas.bind("<Button-5>", self.zoomerM)
        #windows scroll
        self.canvas.bind("<MouseWheel>",self.zoomer)

    #move
    def move_start(self, event):
        self.canvas.scan_mark(event.x, event.y)
    def move_move(self, event):
        self.canvas.scan_dragto(event.x, event.y, gain=1)

    #windows zoom
    def zoomer(self,event):
        if (event.delta > 0):
            self.canvas.scale("all", event.x, event.y, 1.1, 1.1)
        elif (event.delta < 0):
            self.canvas.scale("all", event.x, event.y, 0.9, 0.9)
        self.canvas.configure(scrollregion = self.canvas.bbox("all"))

    #linux zoom
    def zoomerP(self,event):
        self.canvas.scale("all", event.x, event.y, 1.1, 1.1)
        self.canvas.configure(scrollregion = self.canvas.bbox("all"))
    def zoomerM(self,event):
        self.canvas.scale("all", event.x, event.y, 0.9, 0.9)
        self.canvas.configure(scrollregion = self.canvas.bbox("all"))

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

推荐答案

鼠标事件在屏幕坐标"中报告.当你有一个滚动画布，您通常需要将这些数字转换为画布"(即滚动区域)坐标'.

Mouse events are reported in 'screen coordinates'. When you have a scrolled canvas, you often need to convert those numbers to 'canvas (ie. scrollregion) coordinates'.

例如.为您的变焦焦点:

eg. for your zoom focus:

true_x = canvas.canvasx(event.x)
true_y = canvas.canvasy(event.y)

这篇关于用鼠标移动和缩放 tkinter 画布的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！