ImageTk.PhotoImage vs. Tkinter.PhotoImage

[John Carter]

On Mon, 27 Sep 1999 21:42:15 GMT, Les Schaffer <godzilla at netmeg.net>
wrote:

>i need to zoom in on a user specified subset of an image. 
>
>but i am confussed about ImageTk.PhotoImage and
>Tkinter.PhotoImage. the former creates an instance of the latter in
>its self.__photo, used for pasting. but i need access to
>Tkinter.Photoimage's copy and zoom commands. i dont understand why
>ImageTk.PhotoImage doesnt just extend Tkinter.PhotoImage so the copy
>and zoom methods are available, or delegate those calls to __photo
>methods.
>
>also, i notice that in Tkinter.PhotoImage the -from and -to keywords
>for the image copy methods are not explicitly defined. wonder why....
>
>this is my first real foray into using tkinter/PIL for some astro
>work, so please excuse if my questions are stupid.
>
>
>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).

I've simply used the crop method, so I would do something like

image1 = image,crop((x1,y1,x2,y2))
self.photo = ImageTk.PhotoImage(image1)
self.canvas.create_image(0, 0, image=self.photo, anchor=NW)

Do all the image manipulation before I create an instance of Image.TK.

This worked well, except when I called a C extension, there was
clearly something I dodnt usnder stand about PIL's internal data
structures, as my C code accted on the whole origional image. This was
easily solved by using a copy after the crop.

John Carter

jnc at ecs.soton.ac.uk




>
>-- 
>____        Les Schaffer              ___| --->> Engineering R&D <<---
>Theoretical & Applied Mechanics          |  Designspring, Inc. 
>Center for Radiophysics & Space Research |  http://www.designspring.com/
>Cornell Univ.  schaffer at tam.cornell.edu  |  les at designspring.com