/usr/lib/ruby/vendor_ruby/chunky_png/canvas/masking.rb is in ruby-chunky-png 1.2.8-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 | module ChunkyPNG
class Canvas
# The ChunkyPNG::Canvas::Masking module defines methods to perform masking
# and theming operations on a {ChunkyPNG::Canvas}. The module is included into the Canvas class so all
# these methods are available on every canvas.
#
# @see ChunkyPNG::Canvas
module Masking
# Creates a new image, based on the current image but with a new theme color.
#
# This method will replace one color in an image with another image. This is done by
# first extracting the pixels with a color close to the original theme color as a mask
# image, changing the color of this mask image and then apply it on the original image.
#
# Mask extraction works best when the theme colored pixels are clearly distinguishable
# from a background color (preferably white). You can set a tolerance level to influence
# the extraction process.
#
# @param [Integer] old_theme_color The original theme color in this image.
# @param [Integer] new_theme_color The color to replace the old theme color with.
# @param [Integer] bg_color The background color on which the theme colored pixels are placed.
# @param [Integer] tolerance The tolerance level to use when extracting the mask image. Five is
# the default; increase this if the masked image does not extract all the required pixels,
# decrease it if too many pixels get extracted.
# @return [ChunkyPNG::Canvas] Returns itself, but with the theme colored pixels changed.
# @see #change_theme_color!
# @see #change_mask_color!
def change_theme_color!(old_theme_color, new_theme_color, bg_color = ChunkyPNG::Color::WHITE, tolerance = 5)
base, mask = extract_mask(old_theme_color, bg_color, tolerance)
mask.change_mask_color!(new_theme_color)
self.replace!(base.compose!(mask))
end
# Creates a base image and a mask image from an original image that has a particular theme color.
# This can be used to easily change a theme color in an image.
#
# It will extract all the pixels that look like the theme color (with a tolerance level) and put
# these in a mask image. All the other pixels will be stored in a base image. Both images will be
# of the exact same size as the original image. The original image will be left untouched.
#
# The color of the mask image can be changed with {#change_mask_color!}. This new mask image can
# then be composed upon the base image to create an image with a new theme color. A call to
# {#change_theme_color!} will perform this in one go.
#
# @param [Integer] mask_color The current theme color.
# @param [Integer] bg_color The background color on which the theme colored pixels are applied.
# @param [Integer] tolerance The tolerance level to use when extracting the mask image. Five is
# the default; increase this if the masked image does not extract all the required pixels,
# decrease it if too many pixels get extracted.
# @return [Array<ChunkyPNG::Canvas, ChunkyPNG::Canvas>] An array with the base canvas and the mask
# canvas as elements.
# @see #change_theme_color!
# @see #change_mask_color!
def extract_mask(mask_color, bg_color = ChunkyPNG::Color::WHITE, tolerance = 5)
base_pixels = []
mask_pixels = []
pixels.each do |pixel|
if ChunkyPNG::Color.alpha_decomposable?(pixel, mask_color, bg_color, tolerance)
mask_pixels << ChunkyPNG::Color.decompose_color(pixel, mask_color, bg_color, tolerance)
base_pixels << bg_color
else
mask_pixels << (mask_color & 0xffffff00)
base_pixels << pixel
end
end
[ self.class.new(width, height, base_pixels), self.class.new(width, height, mask_pixels) ]
end
# Changes the color of a mask image.
#
# This method works on a canvas extracted out of another image using the {#extract_mask} method.
# It can then be applied on the extracted base image. See {#change_theme_color!} to perform
# these operations in one go.
#
# @param [Integer] new_color The color to replace the original mask color with.
# @raise [ChunkyPNG::ExpectationFailed] when this canvas is not a mask image, i.e. its palette
# has more than once color, disregarding transparency.
# @see #change_theme_color!
# @see #extract_mask
def change_mask_color!(new_color)
raise ChunkyPNG::ExpectationFailed, "This is not a mask image!" if palette.opaque_palette.size != 1
pixels.map! { |pixel| (new_color & 0xffffff00) | ChunkyPNG::Color.a(pixel) }
self
end
end
end
end
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