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
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!
# File lib/chunky_png/canvas/operations.rb, line 365 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
# File lib/chunky_png/canvas/operations.rb, line 375 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
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 89 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 55 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 154 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 174 def crop!(x, y, crop_width, crop_height) if crop_width + x > width raise ChunkyPNG::OutOfBounds, "Original image width is too small!" end if crop_height + y > height raise ChunkyPNG::OutOfBounds, "Original image height is too small!" end if crop_width == width && x == 0 # We only need to crop off the top and/or bottom, so we can take a # shortcut. replace_canvas!(crop_width, crop_height, pixels.slice(y * width, width * crop_height)) else new_pixels = [] for cy in 0...crop_height do new_pixels.concat pixels.slice((cy + y) * width + x, crop_width) end replace_canvas!(crop_width, crop_height, new_pixels) end 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 204 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 217 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 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 239 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 252 def flip_vertically! for y in 0...height do replace_row!(y, row(y).reverse) end self end
Converts the canvas to grayscale, 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
grayscale.
@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 grayscale.
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 21 def grayscale! pixels.map! { |pixel| ChunkyPNG::Color.to_grayscale(pixel) } 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 137 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 110 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 321 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 329 def rotate_180! pixels.reverse! 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.
@return [ChunkyPNG::Canvas] A rotated copy of itself. @see rotate_left! for the in-place version.
# File lib/chunky_png/canvas/operations.rb, line 294 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 305 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.
@return [ChunkyPNG::Canvas] A clockwise-rotated copy. @see rotate_right! for the in place version.
# File lib/chunky_png/canvas/operations.rb, line 268 def rotate_right dup.rotate_right! end
Rotates the image 90 degrees clockwise in place.
This method will change the current canvas.
@return [ChunkyPNG::Canvas] Itself, but rotated clockwise. @see rotate_right for a version that leaves the current canvas intact
# File lib/chunky_png/canvas/operations.rb, line 278 def rotate_right! new_pixels = [] 0.upto(width - 1) { |i| new_pixels += column(i).reverse } replace_canvas!(height, width, new_pixels) 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!
# File lib/chunky_png/canvas/operations.rb, line 340 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
# File lib/chunky_png/canvas/operations.rb, line 350 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
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 394 def check_size_constraints!(other, offset_x, offset_y) if width < other.width + offset_x raise ChunkyPNG::OutOfBounds, "Background image width is too small!" end if height < other.height + offset_y raise ChunkyPNG::OutOfBounds, "Background image height is too small!" end end