blockstRunning Scratch programs#
blockst includes an execution engine that runs Scratch programs visually — for demonstrating program flow and pen drawing. It runs Scratch text only.
scratch-run Module#
#import "@preview/blockst:0.4.0": scratch-run, set-scratch-run
#scratch-run.stage("...", scale: 2)
#scratch-run.grid("...", grid: true)scratch-run.stage() — Stage Canvas#
Renders pen drawing on a stage canvas, like the Scratch stage.
#scratch-run.stage(
program,
language: "en", // locale for block text
size: auto, // (width, height) in pixels (default 480×360)
scale: auto, // drawing scale multiplier
start: auto, // (x: 0, y: 0, angle: 90)
pen: auto, // (down: false, color: ..., size: ...)
background: auto, // background color (e.g. white, black)
cursor: auto, // show/hide turtle cursor (default: true)
border: auto, // show/hide stage border (default: true)
)scratch-run.grid() — Coordinate Grid#
Renders the drawing on a Cartesian coordinate grid with optional axes and grid lines.
#scratch-run.grid(
program,
language: "en", // locale for block text
x: auto, // view bounds (tuple, e.g. (-10, 10))
y: auto, // view bounds (tuple)
step: auto, // grid step size
scale: auto, // drawing scale multiplier
start: auto, // (x: 0, y: 0, angle: 90)
pen: auto, // (down: false, color: ..., size: ...)
background: auto, // background color
axes: auto, // show axis lines (default: false)
grid: auto, // show grid lines (default: false)
grid-style: auto, // grid line stroke (default: 0.5pt + gray)
cursor: auto, // show/hide turtle cursor (default: true)
fit: auto, // auto-fit view to drawing bounds
)set-scratch-run() — Run Global Defaults#
#set-scratch-run(
scale: none, // default scale for all runs
start: none, // (x: 0, y: 0, angle: 90)
pen: none, // (down: false, color: ..., size: ...)
background: none, // default background color
cursor: none, // show/hide turtle cursor (default: true)
stage: none, // (size: (480, 360), border: true)
grid: none, // (visible: false, axes: false, step: auto, style: auto)
)Supported Execution Commands#
| Category | Commands |
|---|---|
| Motion | move, turn-right, turn-left, set-direction, go-to, set-x, set-y, change-x, change-y |
| Pen | pen-down, pen-up, set-pen-color, set-pen-size, change-pen-size, erase-all, stamp, set-pen-param, change-pen-param |
| Variables | set-variable, change-variable, variable |
| Operators | plus, minus, multiply, divide, modulo, random, round, greater, less, equals, op-and, op-or, op-not |
| Control | repeat, repeat-until, if-then, if-else, wait |
| Looks | say, think |
| Shapes | square, triangle, circle, star, spiral |
| German | gehe, drehe-rechts, drehe-links, setze-richtung, gehe-zu, stift-ein, stift-aus, setze-stiftfarbe-auf, setze-stiftdicke, setze-variable, aendere-variable, groesser, kleiner, gleich, und, oder, nicht, mal, geteilt, zufallszahl |
Complete Example#
#let square-program = "
go to x: (-45) y: (45)
pen down
set pen [color v] to (0)
set pen size to (45)
repeat (4)
move (90) steps
turn cw (90) degrees
change pen [color v] by (25)
end"
#set-scratch-run(
stage: (size: (300, 240)),
start: (x: 0, y: 0, angle: 90),
)
#grid(
columns: (auto, auto),
gutter: 6mm,
[#scratch(square-program)],
[#scratch-run.stage(square-program, scale: 2)],
)