Dan Drake dandrake

Displaying Images in Tkinter: PNG vs JPG

The Simple Case: PNG Files with `tk.PhotoImage`

Tkinter has built-in support for a few image formats — PNG, GIF, and PPM/PGM — through tk.PhotoImage. For a PNG file, no third-party library is needed:

import tkinter as tk

Motivation: removing speaker notes from slides

I make reveal.js slides with markdown and convert with pandoc. Sometimes I want to post those slides so my students can access them, but I want to strip out the speaker notes because they usually aren't very useful to them.

Solution: use a pandoc filter

I don't want to edit my source files; I just want the output correct. So, I could do something to the output html slides.

But: I also want to allow for the possibility that I'll want to output to other formats. So the best solution is to tell pandoc to do that filtering while it converts.

A macro that creates constants in Racket

Inspired by this Racket discourse post I tried writing a macro that defines bindings that work like constants in Racket.

Note that the solution here handles using set!; you can't prevent shadowing or redefining these variables -- see the Discourse thread.

	import tkinter as tk

	def main():
	win = tk.Tk()
	win.geometry("400x200")

	label = tk.Label(win, text="Here is an image.")
	label.grid(row=0, column=0)

	my_tk_photoimage = tk.PhotoImage(file="your_image_here.png")

	(defun my/do-command-other-window (count command &optional return-p)
	"Do COMMAND in other-window. The COUNT argument is provided to
	`other-window'.

	The optional RETURN-P argument, if true, will make this return to the
	original window after calling COMMAND.

	The intended way to use this function is by calling it from an
	interactive function that specifies the command:

	public enum Coffee {
	ESPRESSO(2.50, 2),
	LATTE(4.50, 8),
	CAPPUCCINO(4.00, 8),
	AMERICANO(3.00, 8);

	// the 'final' isn't necessary functionally, since you can't change these from outside the class/enum
	// but this does document our intent, and would prevent accidentally adding something inside this enum
	// that modified the field.
	private final double price;

	# my version of Steve Reich's Clapping for Sonic Pi:
	# https://en.wikipedia.org/wiki/Clapping_Music
	# https://youtu.be/lzkOFJMI5i8?si=oaBTc4WBR_DC2SJJ
	# https://sonic-pi.net/

	use_bpm 120

	claps = [1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0].ring

	live_loop :clapping do

	#lang racket

	#\|

	I'm trying to understand parameters in Racket.

	One idea: for a recursive function,
	have a parameter that says how much to indent a debugging print
	statement so that I can see the call stack more clearly.

	#lang racket/base


	;; This is lovely but Exercism doesn't let you (require math)!
	;;
	;; Posted this: https://gist.github.com/dandrake/d9a3e20021a68ed16bce6f5dc79e62eb



	(require racket/contract)