module ChunkyPNG::Canvas::Operations
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
Public Instance Methods
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
# File lib/chunky_png/canvas/operations.rb, line 80 def compose(other, offset_x = 0, offset_y = 0) dup.compose!(other, offset_x, offset_y) 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.
# File lib/chunky_png/canvas/operations.rb, line 54 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
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.
# File lib/chunky_png/canvas/operations.rb, line 139 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.
# File lib/chunky_png/canvas/operations.rb, line 155 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!
# File lib/chunky_png/canvas/operations.rb, line 175 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
# File lib/chunky_png/canvas/operations.rb, line 187 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
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!
# File lib/chunky_png/canvas/operations.rb, line 208 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
# File lib/chunky_png/canvas/operations.rb, line 220 def flip_vertically! for y in 0...height do replace_row!(y, row(y).reverse) end 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}
# File lib/chunky_png/canvas/operations.rb, line 35 def grayscale dup.grayscale! end
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}
# File lib/chunky_png/canvas/operations.rb, line 22 def grayscale! pixels.map! { |pixel| ChunkyPNG::Color.to_grayscale(pixel) } return 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
# File lib/chunky_png/canvas/operations.rb, line 124 def replace(other, offset_x = 0, offset_y = 0) dup.replace!(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.
# File lib/chunky_png/canvas/operations.rb, line 98 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
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!
# File lib/chunky_png/canvas/operations.rb, line 287 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
# File lib/chunky_png/canvas/operations.rb, line 295 def rotate_180! pixels.reverse! return self end
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.
# File lib/chunky_png/canvas/operations.rb, line 262 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.
# File lib/chunky_png/canvas/operations.rb, line 273 def rotate_left! new_pixels = [] (width - 1).downto(0) { |i| new_pixels += column(i) } replace_canvas!(height, width, new_pixels) end
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.
# File lib/chunky_png/canvas/operations.rb, line 236 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.
# File lib/chunky_png/canvas/operations.rb, line 246 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
Protected Instance Methods
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.
# File lib/chunky_png/canvas/operations.rb, line 308 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