Module: ChunkyPNG::Canvas::Resampling

Included in:
ChunkyPNG::Canvas
Defined in:
lib/chunky_png/canvas/resampling.rb

Overview

The ChunkyPNG::Canvas::Resampling module defines methods to perform image resampling to a ChunkyPNG::Canvas.

Currently, only the nearest neighbor algorithm is implemented. Bilinear and cubic algorithms may be added later on.

See Also:

Instance Method Summary collapse

Instance Method Details

#resample_nearest_neighbor(new_width, new_height) ⇒ Object Also known as: resample 



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# File 'lib/chunky_png/canvas/resampling.rb', line 40

def resample_nearest_neighbor(new_width, new_height)
  dup.resample_nearest_neighbor!(new_width, new_height)
end

#resample_nearest_neighbor!(new_width, new_height) ⇒ ChunkyPNG::Canvas

Resamples the canvas.

Parameters:

  • new_width (Integer) —

    The width of the resampled canvas.

  • new_height (Integer) —

    The height of the resampled canvas.

Returns:



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# File 'lib/chunky_png/canvas/resampling.rb', line 17

def resample_nearest_neighbor!(new_width, new_height)
  
  resampled_image = self.class.new(new_width.to_i, new_height.to_i)
  
  width_ratio  = width.to_f / new_width.to_f
  height_ratio = height.to_f / new_height.to_f

  pixels = []
  for y in 1..new_height do
    source_y   = (y - 0.5) * height_ratio + 0.5
    input_y    = source_y.to_i

    for x in 1..new_width do
      source_x = (x - 0.5) * width_ratio + 0.5
      input_x  = source_x.to_i

      pixels << get_pixel([input_x - 1, 0].max, [input_y - 1, 0].max)
    end
  end
  
  replace_canvas!(new_width.to_i, new_height.to_i, pixels)
end