[Tutor] events and popup menus

[Chris Hare]

Thanks Peter - I finally got back to working on this while my dog was having a panic attack from a thunderstorm about 430 AM.  :-)  She is asleep as my feet.  

Anyway, great example and it showed me exactly what i needed to do, AND what I was doing wrong.

I appreciate your help!

On May 3, 2012, at 5:30 AM, Peter Otten wrote:

> Chris Hare wrote:
> 
>> I have four images in a frame.  I want to pop up a menu when the user
>> right clicks on an image, and when they choose an option from the menu,
>> execute the action.
>> 
>> I can create the popup menu, and bind it to the image.  However, what I
>> can't figure out is how to detect in the popup menu code which image fired
>> the event so I can do the right thing (like display a larger version of
>> the image, etc.)
>> 
>> # create a menu
>> self.popup = Menu(self.pictureWindow, tearoff=0)
>> self.popup.add_command(label="Change Picture",
>> command=self.selectPicture) self.popup.add_command(label="Make Primary",
>> command=self.selectPicture) self.popup.add_command(label="Large View",
>> command=self.selectPicture)
> 
> You should have a different callback for every menu item:
> 
> self.popup.add_command(label="Change Picture", command=self.change_picture)
> ...
> self.popup.add_command(label="Large View", command=self.large_view)
> 
> 
>> self.picture1.bind("<Button-1>", self.do_popup)
>> 
>> def do_popup(self,event):
>>            # display the popup menu
>>          try:
>>           self.popup.tk_popup(event.x_root, event.y_root, 0)
>> 
>>                 finally:
>>                         # make sure to release the grab (Tk 8.0a1 only)
>>                         self.popup.grab_release()
>> 
>> Thanks for the advice!
> 
> You can remember the widget from do_popup()'s event argument
> 
> def do_popup(self, event):
>    self.current_picture = event.widget
>    ...
> 
> and later refer to it in the menu callbacks 
> 
> def select_picture(self):
>    picture = self.current_picture
>    ...
> 
> I got a bit distracted struggling with PIL, therefore my "self-contained 
> demo" got rather baroque. You may still find it useful:
> 
> $ cat tk_popup_demo.py
> import sys
> import Tkinter as tk
> import ImageTk
> import Image
> 
> current_label = None
> 
> def do_popup(event):
>    global current_label
>    current_label = event.widget
>    try:
>        popup.tk_popup(event.x_root, event.y_root, 0)
>    finally:
>        popup.grab_release()
> 
> def rotate_picture():
>    image = current_label.photoimage.image.rotate(90)
>    photoimage = ImageTk.PhotoImage(image)
>    photoimage.image = image
>    current_label.photoimage = current_label["image"] = photoimage
> 
> def flip_picture():
>    print "flip picture"
> 
> def load_image(filename, maxsize=(500, 500), padcolor="#f80"):
>    image = Image.open(filename)
>    image.thumbnail(maxsize)
>    if image.size != maxsize:
>        padded_image = Image.new(image.mode, maxsize, color=padcolor)
>        maxx, maxy = maxsize
>        x, y = image.size
>        padded_image.paste(image, ((maxx-x)//2, (maxy-y)//2))
>        image = padded_image
>    assert image.size == maxsize
>    return image
> 
> root = tk.Tk()
> 
> picturefiles = sys.argv[1:4]
> for i, filename in enumerate(picturefiles):
>    image = load_image(filename)
>    photoimage = ImageTk.PhotoImage(image)
>    photoimage.image = image
> 
>    label = tk.Label(root, image=photoimage)
>    label.photoimage = photoimage
>    label.grid(row=0, column=i)
>    label.bind("<Button-3>", do_popup)
> 
> popup = tk.Menu(root, tearoff=0)
> popup.add_command(label="Rotate", command=rotate_picture)
> popup.add_command(label="Flip", command=flip_picture)
> 
> root.mainloop()
> 
> Invoke with a few picture names (all but the first three will be ignored):
> 
> $ python tk_popup_demo.py *.jpg
> 
> 
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