[Image-SIG] ImageTk.PhotoImage vs. Tkinter.PhotoImage

[Fredrik Lundh]

Les Schaffer <godzilla@netmeg.net> wrote:
> so, with code like this:
> 
> ...
>         self.photo = ImageTk.PhotoImage(image)
>         self.canvas.create_image(0, 0, image=self.photo, anchor=NW)
> ...
> 
> i want to create a new PhotoImage consisting of a zoom in on a subset
> of self.photo (i have the x,y coords of the desired zoom area in
> self.photo).

the easiest (and by far fastest) way to do this
is to keep a reference to the original PIL image,
and create a new ImageTk.PhotoImage instance
when necessary.

here's some (untested) sample code:

    ...

        self.image = image

        # display original image
        self.setimage(self.image)

        # display subregion
        im = self.image.transform(
            (512, 512), Image.EXTENT,
            (12.5, 12.5, 27.5, 27.5)
            )
        self.setimage(im)

    ...

    def setimage(self, image):
        self.photo = ImageTk.PhotoImage(image)
        self.canvas.delete("image")
        self.canvas.create_image(0, 0,
            image=self.photo,
            anchor=NW, tag="image"
            )

    ...

hope this helps!

</F>