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March 4, 2014 12:25
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chunky_png: take a part of screenshot(see #crop)
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module ChunkyPNG | |
class Canvas | |
# The ChunkyPNG::Canvas::Operations module defines methods to perform operations | |
# on a {ChunkyPNG::Canvas}. The module is included into the Canvas class so all | |
# these methods are available on every canvas. | |
# | |
# Note that some of these operations modify the canvas, while some operations return | |
# a new canvas and leave the original intact. | |
# | |
# @see ChunkyPNG::Canvas | |
module Operations | |
# Converts the canvas to grascale. | |
# | |
# This method will modify the canvas. The obtain a new canvas and leave the | |
# current instance intact, use {#grayscale} instead. | |
# | |
# @return [ChunkyPNG::Canvas] Returns itself, converted to grayscale. | |
# @see {#grayscale} | |
# @see {ChunkyPNG::Color#to_grayscale} | |
def grayscale! | |
pixels.map! { |pixel| ChunkyPNG::Color.to_grayscale(pixel) } | |
return self | |
end | |
# Converts the canvas to grascale, returning a new canvas. | |
# | |
# This method will not modify the canvas. To modift the current canvas, | |
# use {#grayscale!} instead. | |
# | |
# @return [ChunkyPNG::Canvas] A copy of the canvas, converted to grasycale. | |
# @see {#grayscale!} | |
# @see {ChunkyPNG::Color#to_grayscale} | |
def grayscale | |
dup.grayscale! | |
end | |
# Composes another image onto this image using alpha blending. This will modify | |
# the current canvas. | |
# | |
# If you simply want to replace pixels or when the other image does not have | |
# transparency, it is faster to use {#replace!}. | |
# | |
# @param [ChunkyPNG::Canvas] other The foreground canvas to compose on the | |
# current canvas, using alpha compositing. | |
# @param [Integer] offset_x The x-offset to apply the new foreground on. | |
# @param [Integer] offset_y The y-offset to apply the new foreground on. | |
# @return [ChunkyPNG::Canvas] Returns itself, but with the other canvas composed onto it. | |
# @raise [ChunkyPNG::OutOfBounds] when the other canvas doesn't fit on this one, | |
# given the offset and size of the other canvas. | |
# @see #replace! | |
# @see #compose | |
def compose!(other, offset_x = 0, offset_y = 0) | |
check_size_constraints!(other, offset_x, offset_y) | |
for y in 0...other.height do | |
for x in 0...other.width do | |
set_pixel(x + offset_x, y + offset_y, ChunkyPNG::Color.compose(other.get_pixel(x, y), get_pixel(x + offset_x, y + offset_y))) | |
end | |
end | |
self | |
end | |
# Composes another image onto this image using alpha blending. This will return | |
# a new canvas and leave the original intact. | |
# | |
# If you simply want to replace pixels or when the other image does not have | |
# transparency, it is faster to use {#replace}. | |
# | |
# @param (see #compose!) | |
# @return [ChunkyPNG::Canvas] Returns the new canvas, composed of the other 2. | |
# @raise [ChunkyPNG::OutOfBounds] when the other canvas doesn't fit on this one, | |
# given the offset and size of the other canvas. | |
# | |
# @note API changed since 1.0 - This method now no longer is in place, but returns | |
# a new canvas and leaves the original intact. Use {#compose!} if you want to | |
# compose on the canvas in place. | |
# @see #replace | |
def compose(other, offset_x = 0, offset_y = 0) | |
dup.compose!(other, offset_x, offset_y) | |
end | |
# Replaces pixels on this image by pixels from another pixels, on a given offset. | |
# This method will modify the current canvas. | |
# | |
# This will completely replace the pixels of the background image. If you want to blend | |
# them with semi-transparent pixels from the foreground image, see {#compose!}. | |
# | |
# @param [ChunkyPNG::Canvas] other The foreground canvas to get the pixels from. | |
# @param [Integer] offset_x The x-offset to apply the new foreground on. | |
# @param [Integer] offset_y The y-offset to apply the new foreground on. | |
# @return [ChunkyPNG::Canvas] Returns itself, but with the other canvas placed onto it. | |
# @raise [ChunkyPNG::OutOfBounds] when the other canvas doesn't fit on this one, | |
# given the offset and size of the other canvas. | |
# @see #compose! | |
# @see #replace | |
def replace!(other, offset_x = 0, offset_y = 0) | |
check_size_constraints!(other, offset_x, offset_y) | |
for y in 0...other.height do | |
for d in 0...other.width | |
pixels[(y + offset_y) * width + offset_x + d] = other.pixels[y * other.width + d] | |
end | |
end | |
self | |
end | |
# Replaces pixels on this image by pixels from another pixels, on a given offset. | |
# This method will modify the current canvas. | |
# | |
# This will completely replace the pixels of the background image. If you want to blend | |
# them with semi-transparent pixels from the foreground image, see {#compose!}. | |
# | |
# @param (see #replace!) | |
# @return [ChunkyPNG::Canvas] Returns a new, combined canvas. | |
# @raise [ChunkyPNG::OutOfBounds] when the other canvas doesn't fit on this one, | |
# given the offset and size of the other canvas. | |
# | |
# @note API changed since 1.0 - This method now no longer is in place, but returns | |
# a new canvas and leaves the original intact. Use {#replace!} if you want to | |
# replace pixels on the canvas in place. | |
# @see #compose | |
def replace(other, offset_x = 0, offset_y = 0) | |
dup.replace!(other, offset_x, offset_y) | |
end | |
# Crops an image, given the coordinates and size of the image that needs to be cut out. | |
# This will leave the original image intact and return a new, cropped image with pixels | |
# copied from the original image. | |
# | |
# @param [Integer] x The x-coordinate of the top left corner of the image to be cropped. | |
# @param [Integer] y The y-coordinate of the top left corner of the image to be cropped. | |
# @param [Integer] crop_width The width of the image to be cropped. | |
# @param [Integer] crop_height The height of the image to be cropped. | |
# @return [ChunkyPNG::Canvas] Returns the newly created cropped image. | |
# @raise [ChunkyPNG::OutOfBounds] when the crop dimensions plus the given coordinates | |
# are bigger then the original image. | |
def crop(x, y, crop_width, crop_height) | |
dup.crop!(x, y, crop_width, crop_height) | |
end | |
# Crops an image, given the coordinates and size of the image that needs to be cut out. | |
# | |
# This will change the size and content of the current canvas. Use {#crop} if you want to | |
# have a new canvas returned instead, leaving the current canvas intact. | |
# | |
# @param [Integer] x The x-coordinate of the top left corner of the image to be cropped. | |
# @param [Integer] y The y-coordinate of the top left corner of the image to be cropped. | |
# @param [Integer] crop_width The width of the image to be cropped. | |
# @param [Integer] crop_height The height of the image to be cropped. | |
# @return [ChunkyPNG::Canvas] Returns itself, but cropped. | |
# @raise [ChunkyPNG::OutOfBounds] when the crop dimensions plus the given coordinates | |
# are bigger then the original image. | |
def crop!(x, y, crop_width, crop_height) | |
raise ChunkyPNG::OutOfBounds, "Original image width is too small!" if crop_width + x > width | |
raise ChunkyPNG::OutOfBounds, "Original image height is too small!" if crop_height + y > height | |
new_pixels = [] | |
for cy in 0...crop_height do | |
new_pixels += pixels.slice((cy + y) * width + x, crop_width) | |
end | |
replace_canvas!(crop_width, crop_height, new_pixels) | |
end | |
# Flips the image horizontally, leaving the original intact. | |
# | |
# This will flip the image on its horizontal axis, e.g. pixels on the top will now | |
# be pixels on the bottom. Chaining this method twice will return the original canvas. | |
# This method will leave the original object intact and return a new canvas. | |
# | |
# @return [ChunkyPNG::Canvas] The flipped image | |
# @see #flip_horizontally! | |
def flip_horizontally | |
dup.flip_horizontally! | |
end | |
# Flips the image horizontally in place. | |
# | |
# This will flip the image on its horizontal axis, e.g. pixels on the top will now | |
# be pixels on the bottom. Chaining this method twice will return the original canvas. | |
# This method will leave the original object intact and return a new canvas. | |
# | |
# @return [ChunkyPNG::Canvas] Itself, but flipped | |
# @see #flip_horizontally | |
def flip_horizontally! | |
for y in 0..((height - 1) >> 1) do | |
other_y = height - (y + 1) | |
other_row = row(other_y) | |
replace_row!(other_y, row(y)) | |
replace_row!(y, other_row) | |
end | |
return self | |
end | |
alias_method :flip!, :flip_horizontally! | |
alias_method :flip, :flip_horizontally | |
# Flips the image vertically, leaving the original intact. | |
# | |
# This will flip the image on its vertical axis, e.g. pixels on the left will now | |
# be pixels on the right. Chaining this method twice will return the original canvas. | |
# This method will leave the original object intact and return a new canvas. | |
# | |
# @return [ChunkyPNG::Canvas] The flipped image | |
# @see #flip_vertically! | |
def flip_vertically | |
dup.flip_vertically! | |
end | |
# Flips the image vertically in place. | |
# | |
# This will flip the image on its vertical axis, e.g. pixels on the left will now | |
# be pixels on the right. Chaining this method twice will return the original canvas. | |
# This method will leave the original object intact and return a new canvas. | |
# | |
# @return [ChunkyPNG::Canvas] Itself, but flipped | |
# @see #flip_vertically | |
def flip_vertically! | |
for y in 0...height do | |
replace_row!(y, row(y).reverse) | |
end | |
return self | |
end | |
alias_method :mirror!, :flip_vertically! | |
alias_method :mirror, :flip_vertically | |
# Returns a new canvas instance that is rotated 90 degrees clockwise. | |
# | |
# This method will return a new canvas and leaves the original intact. | |
# See {#rotate_right!} for the in place version. | |
# | |
# @return [ChunkyPNG::Canvas] A clockwise-rotated copy. | |
def rotate_right | |
dup.rotate_right! | |
end | |
# Rotates the image 90 degrees clockwise in place. | |
# | |
# This method will change the current canvas. See {#rotate_right} for | |
# a version that leaves th current canvas intact | |
# | |
# @return [ChunkyPNG::Canvas] Itself, but rotated clockwise. | |
def rotate_right! | |
rotated = self.class.new(height, width) | |
new_pixels = [] | |
0.upto(width - 1) { |i| new_pixels += column(i).reverse } | |
replace_canvas!(height, width, new_pixels) | |
end | |
alias_method :rotate_clockwise, :rotate_right | |
alias_method :rotate_clockwise!, :rotate_right! | |
# Returns an image that is rotated 90 degrees counter-clockwise. | |
# | |
# This method will leave the original object intact and return a new canvas. | |
# See {#rotate_left!} for the in place version. | |
# | |
# @return [ChunkyPNG::Canvas] A rotated copy of itself. | |
def rotate_left | |
dup.rotate_left! | |
end | |
# Rotates the image 90 degrees counter-clockwise in place. | |
# | |
# This method will change the original canvas. See {#rotate_left} for a | |
# version that leaves the canvas intact and returns a new rotated canvas | |
# instead. | |
# | |
# @return [ChunkyPNG::Canvas] Itself, but rotated. | |
def rotate_left! | |
new_pixels = [] | |
(width - 1).downto(0) { |i| new_pixels += column(i) } | |
replace_canvas!(height, width, new_pixels) | |
end | |
alias_method :rotate_counter_clockwise, :rotate_left | |
alias_method :rotate_counter_clockwise!, :rotate_left! | |
# Rotates the image 180 degrees. | |
# This method will leave the original object intact and return a new canvas. | |
# | |
# @return [ChunkyPNG::Canvas] The rotated image. | |
# @see #rotate_180! | |
def rotate_180 | |
dup.rotate_180! | |
end | |
# Rotates the image 180 degrees in place. | |
# | |
# @return [ChunkyPNG::Canvas] Itself, but rotated 180 degrees. | |
# @see #rotate_180 | |
def rotate_180! | |
pixels.reverse! | |
return self | |
end | |
# Trims the border around the image, presumed to be the color of the first pixel. | |
# | |
# @param [Integer] border The color to attempt to trim. | |
# @return [ChunkyPNG::Canvas] The trimmed image. | |
# @see #trim! | |
def trim(border = pixels.first) | |
dup.trim! | |
end | |
# Trims the border around the image in place. | |
# | |
# @param [Integer] border The color to attempt to trim. | |
# @return [ChunkyPNG::Canvas] Returns itself, but with the border trimmed. | |
# @see #trim | |
def trim!(border = pixels.first) | |
x1 = [*0...width].index { |c| column(c).uniq != [border] } | |
x2 = [*0...width].rindex { |c| column(c).uniq != [border] } | |
y1 = [*0...height].index { |r| row(r).uniq != [border] } | |
y2 = [*0...height].rindex { |r| row(r).uniq != [border] } | |
crop! x1, y1, x2 - x1 + 1, y2 - y1 + 1 | |
end | |
# Draws a border around the image. | |
# | |
# @param [Integer] size The size of the border. | |
# @param [Integer] color The color of the border. | |
# @return [ChunkyPNG::Canvas] Returns a bordered version of the image. | |
# @see #border! | |
def border(size, color = ChunkyPNG::Color::BLACK) | |
dup.border!(size, color) | |
end | |
# Draws a border around the image in place. | |
# | |
# @param [Integer] size The size of the border. | |
# @param [Integer] color The color of the border. | |
# @return [ChunkyPNG::Canvas] Returns itself with the border added. | |
# @see #border | |
def border!(size, color = ChunkyPNG::Color::BLACK) | |
new_width = width + size * 2 | |
new_height = height + size * 2 | |
bg = Canvas.new(new_width, new_height, color).replace(self, size, size) | |
replace_canvas!(new_width, new_height, bg.pixels) | |
end | |
protected | |
# Checks whether another image has the correct dimension to be used for an operation | |
# on the current image, given an offset coordinate to work with. | |
# @param [ChunkyPNG::Canvas] other The other canvas | |
# @param [Integer] offset_x The x offset on which the other image will be applied. | |
# @param [Integer] offset_y The y offset on which the other image will be applied. | |
# @raise [ChunkyPNG::OutOfBounds] when the other image doesn't fit. | |
def check_size_constraints!(other, offset_x, offset_y) | |
raise ChunkyPNG::OutOfBounds, "Background image width is too small!" if width < other.width + offset_x | |
raise ChunkyPNG::OutOfBounds, "Background image height is too small!" if height < other.height + offset_y | |
end | |
end | |
end | |
end |
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