Stumpy Utils

A collection of drawing functions for stumpy_core, stumpy_png, ...

Usage

Install the stumpy_utils shard

1. shards init
2. Add the dependency to the shard.yml file

...
dependencies:
stumpy_utils:
github: stumpycr/stumpy_utils
...

3. shards install

You also need to install and require (at least) one of the image extensions ( stumpy_png, stumpy_gif ) or stumpy_core.

Latest Release

Canvas

canvas.line(x0, y0, x1, y1, color = RGBA::BLACK)

Use the Xiaolin Wo algorithm to draw an antialiased line from (x0, y0) to (x1, y1). x0, etc can be floats, too.

Example

require"stumpy_png"require"stumpy_utils"includeStumpyPNG
record Branch, x0 : Int32, y0 : Int32, dir : Int32, length : Float64doRADIANTS=Math::PI/180.0FACTOR= (0.6..1.0)
ANGLE= (30..90)
defx1; x0 + (Math.sin(dir *RADIANTS) * length).to_i; enddefy1; y0 + (Math.cos(dir *RADIANTS) * length).to_i; enddefsplit
angle = rand(ANGLE) /2
[Branch.new(x1, y1, dir + angle, length * rand(FACTOR)),
Branch.new(x1, y1, dir - angle, length * rand(FACTOR))]
endend
branches = [Branch.new(128, 256, 180, 50.0)]
canvas =Canvas.new(256, 256, RGBA::WHITE)
10.times do |i|
branches = branches.flat_map do |b|
canvas.line(b.x0, b.y0, b.x1, b.y1, RGBA::DARKGREEN)
b.split
endendStumpyPNG.write(canvas, "tree.png")

canvas.circle(center_x, center_y, radius, color = RGBA::BLACK, filled = false)

Use the Xiaolin Wo algorithm to draw an antialiased (filled) circle around (center_x, center_y).

Example

require"stumpy_png"require"stumpy_utils"includeStumpyPNG
canvas =Canvas.new(400, 400, RGBA::WHITE)
colors = [RGBA::WHITE, RGBA::DARKSLATEGRAY, RGBA::LIGHTBLUE, RGBA::RED, RGBA::YELLOW]
colors.each_with_index do |color, i|
radius = (colors.size - i) *40
canvas.circle(200, 200, radius, color, true)
end
(colors.size *2).times do |i|
radius = ((colors.size *2) - i) *20
canvas.circle(200, 200, radius, RGBA::BLACK, false)
endStumpyPNG.write(canvas, "circles.png")

canvas.fill_pilygon(vertices, color = RGBA::BLACK)

Use the scanline algorithm to fill a polygon defined by an arbitrary set of vertices.

vertices should be an array of objects that respond to .x and .y methods. StumpyCore::Point is provided as a default implementation.

Example

require"stumpy_png"require"stumpy_utils"includeStumpyPNG
canvas =Canvas.new(400, 400, RGBA::WHITE)
# triangle
canvas.fill_polygon [Point.new(150.0, 50.0), Point.new(250.0, 200.0), Point.new(50.0, 200.0)], RGBA::RED# pentagon
num_points =5
radius =100
center =Point.new 200.0, 280.0
points =0.upto(num_points).map do |n|
angle =2.0*Math::PI*n/num_points -Math::PI/2.0Point.new Math.cos(angle)*radius + center.x, Math.sin(angle)*radius + center.y
end.to_a
canvas.fill_polygon points, RGBA::BLUE# star
center =Point.new 280.0, 150.0
points =0.upto(num_points*2).map do |n|
angle =Math::PI*n/num_points -Math::PI/2.0
r = n %2==0? radius : radius/2.0Point.new Math.cos(angle)*r + center.x, Math.sin(angle)*r + center.y
end.to_a
canvas.fill_polygon points, RGBA::GREENStumpyPNG.write(canvas, "polygons.png")

canvas.text(x, baseline_y, text, font : PCFParser::FONT, color = RGBA:BACK)

NOTE: The fonts are not included in this repo.

On linux, you can find them using fc-list | grep '.pcf'. (The files need to be unpacked using gunzip before using them)

require"stumpy_png"require"stumpy_utils"includeStumpyPNG
canvas =Canvas.new(500, 80, RGBA::WHITE)
font1 =PCFParser::Font.from_file("./fonts/10x20.pcf")
font2 =PCFParser::Font.from_file("./fonts/helvR18.pcf")
text ="The quick brown fox jumps over the lazy dog"
canvas.text(10, 30, text, font1)
canvas.text(10, 60, text, font2, RGBA::BLUE)
StumpyPNG.write(canvas, "text.png")

Contributors

Thanks goes to these wonderful people (emoji key):

Leon 💻	Daniel Huffman 💻	Andy Selvig 💻	Nishant Shah 💻

This project follows the all-contributors specification. Contributions of any kind welcome!