Am 26.06.14 12:39, schrieb Peter Tomcsanyi:
"Christian Gollwitzer" <aurio...@gmx.de> wrote in message
news:lofciv$nq6$1...@dont-email.me...
For PNG image support you can load either the Img package which gives
support for a large variety of images, or the smaller tkpng package.


My first Google search for
"tkpng" "python"
gave no usable results. So I am not sure if and how can I use these Tk
extensions from Python...

As I said, it doesn't have a special interface, you just load it and that's it. So if you do a tk.eval("package require tkpng"), your Tk.PhotoImage will magically recognize PNG. I don't know how widespread the installation is, but compilation is easy. An alternative is the widely available Img package, which adds support for many image formats like gif, bmp, jpeg, tga, tiff etc. On my Mac it came with the OS (I think); you'll do Tk.eval("package require Img"). Since there are no additional commands, it'll just work from Python as well. An alternative employed by Pythonistas is to load the image using PIL and create a Tk PhotoImage via the ImageTk bridge.

And finally I want to show the picture(s) on a Tk-based Canvas on top of
each other with properly handled semi-transparency.

This has been in the canvas for a long time, if you managed to create an image with an alpha channel.

In our project we want to use as little as possible additonal packages
because we expect that the end-users will use several platforms
(Windows, Mac, Linux) and installing any extra Python-related package on
non-Windows platform seems to be a nightmare, at least that is the
result of the past three months of experience.

I understand.

The need to go to the command line level for such a basic thing like
installing or uninstalling something seems to me like going 20 to 30
years back in history. We cannot expect that our end-users (especially
the Mac-based ones) will have that expertise even if they have enough
expertise to program in Python when it is finally correctly installed on
their computers.

On the Mac you can create an APP bundle which contains everything, including extra dependencies. It is a folder with a special structure, you put it into a DMG archive and it matches the expectation a Mac user has of an "installer". Unfortunately these things are very system-dependent, and it's a lot of work to provide deployment (do program icons, setup file associations etc.)


For angled text it's right, I don't know, there used to be some hacks
before, it's probably not possible in a clean way.

I was actually negatively surprised by the lack of this very basic
feature (especially in a vector-graphics-based environment)

Yes this was a long-deferred feature due to its inhomogeneous implementation on the supported platforms. There were some extensions like 10 years ago to do it, but only in 8.6 (2012) it made it into the core Tk.

        Christian

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