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
# 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
pixels[(y + offset_y) * width + offset_x, other.width] = other.pixels[y * other.width, other.width]
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, "Image width is too small!" if crop_width + x > width
raise ChunkyPNG::OutOfBounds, "Image width 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
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