Tkinter Listobox Selection反复调用/自动刷新功能

Question

I am running a GUI in Python 3 with Tkinter implementation.

I am populating a Listbox with some values that I query from a database and on select of a result from the Listbox, I "bind" a function.

tagsList.bind('<<ListboxSelect>>', get_anchors)

This function/event widget, queries again another database that has saved the location of some PNG images and imports them to the GUI using: ImageTk.PhotoImage(Image.open(path)) , as PhotoImage. It populates a grid with all these images loaded, as you may see in the code below:

def get_anchors(event):
    lb = event.widget
    index = lb.curselection()[0]
    tag_name = lb.get(index)

    # Get the anchor list from the database row
    alist = []
    for row in conn.execute("SELECT anchor FROM \"" + tag_name + "\" ORDER BY anchor"):
        alist.append(row[0])

    # ===== Import PNG Images =====
    i = 1
    for anchor in alist:
        j = 1
        for key in measurements:
            path = conn.execute("SELECT \"" + key + "\" FROM \"" + tag_name + "\" WHERE anchor = \"" + anchor +"\"").fetchone()[0]
            photo = ImageTk.PhotoImage(Image.open(path))
            label = tkinter.Label(mainWindow, relief="sunken", image=photo)
            label.image = photo
            label.grid(row=i, column=j, sticky='nsew')
            j += 1
        i += 1

The Problem: The PNG images are changing over the time, they are basically replaced with new generated ones from another program. So, I was wondering if the is a way to autorefresh/load again the newly PNG files, without having to click/select again the same result from the Listbox, that I already have it selected.

The PNG images are generated every 5 seconds, if that helps and they are basically replacing the existing ones(same file name, location etc.). I was hoping that there might be something like a constant autorefresh feature/method or at least a way to call this get_anchors function repeatedly once a specific result is selected from the Listbox.

I can't really find something that will enable this functionality and the only way to go right now, is by clicking again the option that refreshes the grid with the new PNGs by calling again the get_anchors .

Answer 1

Not entirely sure why it was not working before with the lb.after(5000, get_anchors, args=(event,)) , but it is working now in the format lb.after(5000, get_anchors, event) .

I am basically calling a function from the main Tkinter code like this:

tagsList.bind('<<ListboxSelect>>', get_anchors)

which is a listbox and once I select my choice, it calls the get_anchors function, which I bind to it. Then, all I wanted was to re-call the function every 6 seconds from within the same function get_anchors . The code looks like:

def get_anchors(event):
    # ===== Clear canvas and re-assign it on GUI =====
    canvas.delete("all")
    canvas.grid(row=1, column=1, sticky='nsew', rowspan=17, columnspan=5, padx=(10, 0))
    image_plots = tkinter.Frame(canvas, background='white')
    canvas.create_window((0,0), window=image_plots, anchor='nw')

    lb = event.widget
    index = lb.curselection()[0]
    tag_name = lb.get(index)

    # Get the anchor list from the database row
    alist = []
    for row in conn.execute("SELECT anchor FROM \"" + tag_name + "\" ORDER BY anchor"):
        alist.append(row[0])

    # ===== Import PNG Images =====
    i = 1
    for anchor in alist:
        j = 1
        for key in measurements:
            path = conn.execute("SELECT \"" + key + "\" FROM \"" + tag_name + "\" WHERE anchor = \"" + anchor +"\"").fetchone()[0]
            photo = ImageTk.PhotoImage(Image.open(path))
            label = tkinter.Label(image_plots, relief="sunken", image=photo)
            label.image = photo  # Keeping reference is needed
            label.grid(row=i, column=j, sticky='nsew')
            j += 1
        i += 1

    # Refresh PNGs every 6s; they are generated roughly every 5s
    mainWindow.after(6000, get_anchors, event)

This solution at the last line works for refreshing the Canvas and populating it with the new PNGs. With the args=(event,) solution, it did not work.