class StumpyCore::Canvas

• StumpyCore::Canvas
• Reference
• Object

Overview

A canvas is 2D array of RGBA pixels

To create a canvas of size 400 x 200

canvas = StumpyCore::Canvas.new(400, 200)

The default background color is transparent, but it can be passed in as a parameter or as a block that returns the color value for each {x, y} pair.

canvas2 = StumpyCore::Canvas.new(400, 200, RGBA::WHITE)

canvas3 = StumpyCore::Canvas.new(256, 256) do |x, y|
  RGBA.from_rgb_n(x, y, 255, 8)
end

Because of the way pixels are stored in a Slice, Canvases are limited to Int32::MAX = 2147483647 pixels in total, e.g. a maximal size of 46340x46340 for a square image.

Defined in:

stumpy_core/canvas.cr

Constructors

• .new(width : Int32, height : Int32, background = RGBA.new(0_u16, 0_u16, 0_u16, 0_u16))
• .new(width : Int32, height : Int32, &)

Instance Method Summary

• #==(other)

  Two canvases are considered equal if they are of equal size and all their pixels are equal

• #[](x, y)

  Short form for #get

• #[]=(x, y, color)

  Short form for #set

• #each_row(&)

  Iterate over each row of the canvas (a Slice(RGBA) of size @width).

• #get(x, y)

  Get the value of pixel (x, y) without checking if (x, y) is a valid position.

• #height : Int32
• #includes_pixel?(x, y)

  Check if pixel (x, y) is part of this canvas.

• #map(&)

  Same as #map!, but instead of mutating the current canvas, a new one is created and returned

• #map!(&)

  Modify pixels by applying a function (color, x, y) -> new_color to each pixel of the current canvas, e.g.

• #map_with_index(&)

  Same as #map but passes along a fourth parameter with the index in the #pixels slice

• #map_with_index!(&)

  Same as #map! but passes along a fourth parameter with the index in the #pixels slice

• #paste(canvas : Canvas, x, y)

  Past the contents of a second Canvas into this one, starting at position (x, y).

• #pixels : Slice(RGBA)
• #safe_get(x : Int32, y : Int32) : RGBA | Nil

  Same as #get, but returns nil if (x, y) are outside of the canvas

• #safe_set(x : Int32, y : Int32, color : RGBA) : Bool

  Same as #set, but only sets the pixel, if it is part of the canvas.

• #set(x, y, color)

  Set the value of pixel (x, y) to color without checking if (x, y) is a valid position.

• #width : Int32
• #wrapping_get(x : Int32, y : Int32) : RGBA

  Same as #get, but if x ore y are outside of the canvas, wrap them over at the edges.

• #wrapping_set(x : Int32, y : Int32, color : RGBA)

  Same as #set, but wrapping along the canvas edges.

Constructor Detail

Instance Method Detail