Class: Vizcore::Renderer::SnapshotRenderer::Canvas

Inherits:
Object
  • Object
show all
Defined in:
lib/vizcore/renderer/snapshot_renderer.rb

Overview

Tiny RGBA canvas with alpha blending and a few primitive drawing helpers.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(width:, height:, transparent: false) ⇒ Canvas

Returns a new instance of Canvas.



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 935

def initialize(width:, height:, transparent: false)
  @width = width
  @height = height
  @bytes = String.new(capacity: width * height * 4, encoding: Encoding::BINARY)
  alpha = transparent ? 0 : 255
  @bytes << ([0, 0, 0, alpha].pack("C4") * (width * height))
end

Instance Attribute Details

#bytes ⇒ Object (readonly)

Returns the value of attribute bytes.



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 943

def bytes
  @bytes
end

#height ⇒ Object (readonly)

Returns the value of attribute height.



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 943

def height
  @height
end

#width ⇒ Object (readonly)

Returns the value of attribute width.



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 943

def width
  @width
end

Instance Method Details

#draw_circle_outline(cx, cy, radius, color, alpha:) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 970

def draw_circle_outline(cx, cy, radius, color, alpha:)
  segments = 96
  previous = nil
  (0..segments).each do |index|
    angle = (index.to_f / segments) * Math::PI * 2
    point = [cx + Math.cos(angle) * radius, cy + Math.sin(angle) * radius]
    draw_line(previous[0], previous[1], point[0], point[1], color, alpha: alpha) if previous
    previous = point
  end
end

#draw_label(text, x:, y:, color:, alpha:, letter_spacing: 0.0) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 1018

def draw_label(text, x:, y:, color:, alpha:, letter_spacing: 0.0)
  chars = text.each_byte.first(24)
  char_width = 14 + Float(letter_spacing).clamp(0.0, 96.0).round
  total_width = chars.length * char_width
  start_x = x.round - total_width / 2
  chars.each_with_index do |byte, index|
    height_factor = 0.35 + (byte % 9) * 0.07
    fill_bar(start_x + index * char_width, y.round, 9, (42 * height_factor).round, color, alpha)
  end
end

#draw_line(x1, y1, x2, y2, color, alpha:) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 991

def draw_line(x1, y1, x2, y2, color, alpha:)
  x1 = x1.round
  y1 = y1.round
  x2 = x2.round
  y2 = y2.round
  steps = [(x2 - x1).abs, (y2 - y1).abs].max
  return blend_pixel(x1, y1, color, alpha) if steps.zero?

  steps.times do |step|
    t = step.to_f / steps
    blend_pixel(interpolate(x1, x2, t).round, interpolate(y1, y2, t).round, color, alpha)
  end
end

#draw_rect_outline(x, y, rect_width, rect_height, color, alpha:) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 963

def draw_rect_outline(x, y, rect_width, rect_height, color, alpha:)
  draw_line(x, y, x + rect_width, y, color, alpha: alpha)
  draw_line(x + rect_width, y, x + rect_width, y + rect_height, color, alpha: alpha)
  draw_line(x + rect_width, y + rect_height, x, y + rect_height, color, alpha: alpha)
  draw_line(x, y + rect_height, x, y, color, alpha: alpha)
end

#draw_wave(y_base, amplitude:, color:, alpha:, height_scale: 1.0) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 953

def draw_wave(y_base, amplitude:, color:, alpha:, height_scale: 1.0)
  previous = nil
  width.times do |x|
    phase = (x.to_f / width) * Math::PI * 4.0
    y = y_base + Math.sin(phase) * height * (0.06 + amplitude * 0.08) * height_scale
    draw_line(previous[0], previous[1], x, y, color, alpha: alpha) if previous
    previous = [x, y]
  end
end

#fill_circle(cx, cy, radius, color, alpha:) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 1005

def fill_circle(cx, cy, radius, color, alpha:)
  cx = cx.round
  cy = cy.round
  radius = radius.round
  (cy - radius).upto(cy + radius) do |y|
    (cx - radius).upto(cx + radius) do |x|
      next if ((x - cx)**2) + ((y - cy)**2) > radius**2

      blend_pixel(x, y, color, alpha)
    end
  end
end

#fill_gradient(top, bottom) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 945

def fill_gradient(top, bottom)
  height.times do |y|
    t = y.to_f / [height - 1, 1].max
    color = 3.times.map { |index| interpolate(top[index], bottom[index], t).round }
    width.times { |x| set_pixel(x, y, color, 255) }
  end
end

#fill_rect(x, y, rect_width, rect_height, color, alpha:) ⇒ Object 



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# File 'lib/vizcore/renderer/snapshot_renderer.rb', line 981

def fill_rect(x, y, rect_width, rect_height, color, alpha:)
  start_x = x.round
  end_x = (x + rect_width).round
  start_y = y.round
  end_y = (y + rect_height).round
  start_y.upto(end_y) do |py|
    start_x.upto(end_x) { |px| blend_pixel(px, py, color, alpha) }
  end
end