Tkinter Canvas：在移动物体上缩放

Question

我不知道我的问题是愚蠢的还是棘手的。

因此，我使用 Tkinter 和 Canvas 成功实现了一个完美运行的滚动/缩放功能，感谢这篇文章 Move and zoom a tkinter canvas with mouse。我还添加了一个绑定以在窗口大小更改时调整画布大小而不会出现问题。

使用coords 和after，我可以轻松移动object。

当我尝试将所有内容结合起来时，麻烦就来了。

• 移动和滚动：没问题
• 滚动和缩放：好的
• 缩放、移动和滚动：不起作用

下面的代码重现了这个问题（python 2.7，在 Windows 上工作）。就我所见，问题来自缩放，可能是由对象的coords 的变化引起的，导致画布调整大小，然后禁用缩放？如果是这种情况，我需要帮助来解决这个问题。如果不是这样，我需要帮助才能找到问题...

通过删除/禁用self.master.after(50, self.Display) 行，移动不再发生。

import Tkinter as tk
import math

class Example:
    def __init__ (self, master):
        self.master = master
        self.interval = 0
        self.SizeX, self.SizeY = master.winfo_width(), master.winfo_height()
        #Canvas Frame
        self.SystemCanvasFrame = tk.Frame(master, bg='black')
        self.SystemCanvasFrame.grid(row=0, column=0)

        #Canvas
        self.SystemCanvas = tk.Canvas(self.SystemCanvasFrame, width=int(self.SizeX*0.75)-20, height=self.SizeY-20, bg="black")
        self.SystemCanvas.focus_set()
        self.xsb = tk.Scrollbar(self.SystemCanvasFrame, orient="horizontal", command=self.SystemCanvas.xview)
        self.ysb = tk.Scrollbar(self.SystemCanvasFrame, orient="vertical", command=self.SystemCanvas.yview)
        self.SystemCanvas.configure(scrollregion=(-500,-500,500,500))
        self.SystemCanvas.configure(yscrollcommand=self.ysb.set, xscrollcommand=self.xsb.set)
        #add the canvas with scroll bar in grid format
        self.xsb.grid(row=1, column=0, sticky="ew")
        self.ysb.grid(row=0, column=1, sticky="ns")
        self.SystemCanvas.grid(row=0, column=0, sticky="nsew")

        # This is what enables using the mouse to slide the window:
        self.SystemCanvas.bind("<ButtonPress-1>", self.move_start)
        self.SystemCanvas.bind("<B1-Motion>", self.move_move)
        #windows scroll
        self.SystemCanvas.bind("<MouseWheel>",self.zoomer)        
        #resize the main window
        self.master.bind('<Configure>', self.UpdateCanvasSize)

        #Create Objects
        self.Size = 5 #object Size
        x0 = 0
        y0 = 0
        x1 = self.Size
        y1 = self.Size
        self.SystemCanvas.create_oval(x0,y0,x1,y1, fill='green', outline='green', width=3, tags='Green')
        self.SystemCanvas.create_oval(x0,y0,x1,y1, fill='red', outline='red', width=3, tags='Red')
        self.SystemCanvas.create_oval(x0,y0,x1,y1, fill='yellow', outline='yellow', width=1, tags='Yellow')

        self.Display()

    def Display(self):
        self.interval += 0.5 #speed parameter
        GreenPos = self.UpdatePosition(0.1*self.interval, (0,0), 50)
        RedPos = self.UpdatePosition(0.02*self.interval+180, (0,0), 200)
        YellowPos = self.UpdatePosition(0.3*self.interval, RedPos, 10)

        self.MoveObject('Green', GreenPos)
        self.MoveObject('Red', RedPos)
        self.MoveObject('Yellow', YellowPos)

        self.master.after(50, self.Display) #Disable to zoom

    def MoveObject (self, Obj, pos): #only move object that are in the field of view
        """Move Obj to the given position (tuple - xy)"""
        ID = self.SystemCanvas.find_withtag(Obj)      
        #Convert the Center of the object to the coo need for tk
        x0 = pos[0] - self.Size/2.0 #radius of the circle
        y0 = pos[1] - self.Size/2.0
        x1 = pos[0] + self.Size/2.0
        y1 = pos[1] + self.Size/2.0
        self.SystemCanvas.coords(ID, x0,y0,x1,y1)

    def UpdatePosition(self, angle, center, distance):
        """Calculate next object position around the Center at the Distance and speed determine by Angle (in Radian) - Center of the object"""
        h = center[0]
        k = center[1]
        radius = distance
        Rad = angle
        x = h+radius*math.cos(Rad)
        y = k+radius*math.sin(Rad)
        return (x, y)

    def UpdateCanvasSize(self, event):
        """Permit to resize the canvas to the window"""
        self.SizeX, self.SizeY = self.master.winfo_width(), self.master.winfo_height()
        self.SystemCanvas.config(width=int(self.SizeX*0.75)-20, height=self.SizeY-20)

    def move_start(self, event):
        """Detect the beginning of the move"""
        self.SystemCanvas.scan_mark(event.x, event.y)
        self.SystemCanvas.focus_set() #security, set the focus on the Canvas

    def move_move(self, event):
        """Detect the move of the mouse"""
        self.SystemCanvas.scan_dragto(event.x, event.y, gain=1)

    def zoomer(self,event):
        """Detect the zoom action by the mouse. Zoom on the mouse focus"""
        true_x = self.SystemCanvas.canvasx(event.x)
        true_y = self.SystemCanvas.canvasy(event.y)
        if (event.delta > 0):
            self.SystemCanvas.scale("all", true_x, true_y, 1.2, 1.2)
        elif (event.delta < 0):
            self.SystemCanvas.scale("all", true_x, true_y, 0.8, 0.8)
        self.SystemCanvas.configure(scrollregion = self.SystemCanvas.bbox("all"))

if __name__ == '__main__':
    root = tk.Tk()
    root.geometry('1125x750')
    app = Example(root)
    root.mainloop()

Answer 1

我是 Tkinter 的新手，所以这可能不是最优雅的解决方案，但我希望它能让您了解如何解决问题。

zoomer 方法会缩放您的坐标，但这些坐标会在您调用MoveObject 或UpdatePosition 时重置。我添加了跟踪比例因子self.scale 的代码和一个基于比例因子缩放给定坐标的方法update_coord。最后，我在MoveObject 和UpdatePosition 方法中调用了update_coord。

这是工作代码；

import Tkinter as tk
import math

class Example:
    def __init__ (self, master):

        self.scale = 1 #Added

        self.master = master
        self.interval = 0
        self.SizeX, self.SizeY = master.winfo_width(), master.winfo_height()
        #Canvas Frame
        self.SystemCanvasFrame = tk.Frame(master, bg='black')
        self.SystemCanvasFrame.grid(row=0, column=0)

        #Canvas
        self.SystemCanvas = tk.Canvas(self.SystemCanvasFrame, width=int(self.SizeX*0.75)-20, height=self.SizeY-20, bg="black")
        self.SystemCanvas.focus_set()
        self.xsb = tk.Scrollbar(self.SystemCanvasFrame, orient="horizontal", command=self.SystemCanvas.xview)
        self.ysb = tk.Scrollbar(self.SystemCanvasFrame, orient="vertical", command=self.SystemCanvas.yview)
        self.SystemCanvas.configure(scrollregion=(-500,-500,500,500))
        self.SystemCanvas.configure(yscrollcommand=self.ysb.set, xscrollcommand=self.xsb.set)
        #add the canvas with scroll bar in grid format
        self.xsb.grid(row=1, column=0, sticky="ew")
        self.ysb.grid(row=0, column=1, sticky="ns")
        self.SystemCanvas.grid(row=0, column=0, sticky="nsew")

        # This is what enables using the mouse to slide the window:
        self.SystemCanvas.bind("<ButtonPress-1>", self.move_start)
        self.SystemCanvas.bind("<B1-Motion>", self.move_move)
        #windows scroll
        self.SystemCanvas.bind("<MouseWheel>",self.zoomer)        
        #resize the main window
        self.master.bind('<Configure>', self.UpdateCanvasSize)

        #Create Objects
        self.Size = 5 #object Size
        x0 = 0
        y0 = 0
        x1 = self.Size
        y1 = self.Size
        self.SystemCanvas.create_oval(x0,y0,x1,y1, fill='green',   outline='green', width=3, tags='Green')
        self.SystemCanvas.create_oval(x0,y0,x1,y1, fill='red', outline='red', width=3, tags='Red')
        self.SystemCanvas.create_oval(x0,y0,x1,y1, fill='yellow', outline='yellow', width=1, tags='Yellow')

        self.Display()


    #**Added Method
    def update_coord(self, coord):
        """Calculate the scaled cordinate for a given cordinate based on the zoomer scale factor"""
        new_coord = [coord_i * self.scale for coord_i in coord]
        return new_coord


    def Display(self):
        self.interval += 0.5 #speed parameter
        GreenPos = self.UpdatePosition(0.1*self.interval, (0,0), 50)
        RedPos = self.UpdatePosition(0.02*self.interval+180, (0,0), 200)
        YellowPos = self.UpdatePosition(0.3*self.interval, RedPos, 10)

        self.MoveObject('Green', GreenPos)
        self.MoveObject('Red', RedPos)
        self.MoveObject('Yellow', YellowPos)


        self.master.after(1, self.Display) #Disable to zoom

    def MoveObject (self, Obj, pos): #only move object that are in the field of view
        """Move Obj to the given position (tuple - xy)"""
        ID = self.SystemCanvas.find_withtag(Obj)      
        #Convert the Center of the object to the coo need for tk
        x0 = pos[0] - self.Size/2.0 #radius of the circle
        y0 = pos[1] - self.Size/2.0
        x1 = pos[0] + self.Size/2.0
        y1 = pos[1] + self.Size/2.0
        c_0 = self.update_coord([x0, y0]) #Added
        c_1 = self.update_coord([x1, y1]) #Added
        self.SystemCanvas.coords(ID, c_0[0], c_0[1], c_1[0], c_1[1]) #Added/Edited 

    def UpdatePosition(self, angle, center, distance):
        """Calculate next object position around the Center at the Distance and speed determine by Angle (in Radian) - Center of the object"""
        h = center[0]
        k = center[1]
        radius = distance
        Rad = angle
        x = h+radius*math.cos(Rad)
        y = k+radius*math.sin(Rad)
        return self.update_coord([x, y]) #Added/Edited

    def UpdateCanvasSize(self, event):
        """Permit to resize the canvas to the window"""
        self.SizeX, self.SizeY = self.master.winfo_width(), self.master.winfo_height()
        self.SystemCanvas.config(width=int(self.SizeX*0.75)-20, height=self.SizeY-20)

    def move_start(self, event):
        """Detect the beginning of the move"""
        self.SystemCanvas.scan_mark(event.x, event.y)
        self.SystemCanvas.focus_set() #security, set the focus on the Canvas

    def move_move(self, event):
        """Detect the move of the mouse"""
        self.SystemCanvas.scan_dragto(event.x, event.y, gain=1)

    def zoomer(self,event):
        """Detect the zoom action by the mouse. Zoom on the mouse focus"""
        true_x = self.SystemCanvas.canvasx(event.x)
        true_y = self.SystemCanvas.canvasy(event.y)
        if (event.delta > 0):
            self.SystemCanvas.scale("all", true_x, true_y, 1.2, 1.2)
            self.scale *= 1.2 #**Added
        elif (event.delta < 0):
            self.SystemCanvas.scale("all", true_x, true_y, 0.8, 0.8)
            self.scale *= 0.8 #**Added
        #self.SystemCanvas.configure(scrollregion =  self.SystemCanvas.bbox("all")) #**Removed (This disables scrollbar after zoom)

if __name__ == '__main__':
    root = tk.Tk()
    root.geometry('1125x750')
    app = Example(root)
    root.mainloop()