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 366 def border(size, color = ChunkyPNG::Color::BLACK) 367 dup.border!(size, color) 368 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 376 def border!(size, color = ChunkyPNG::Color::BLACK) 377 new_width = width + size * 2 378 new_height = height + size * 2 379 380 bg = Canvas.new(new_width, new_height, color).replace(self, size, size) 381 replace_canvas!(new_width, new_height, bg.pixels) 382 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 90 def compose(other, offset_x = 0, offset_y = 0) 91 dup.compose!(other, offset_x, offset_y) 92 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 56 def compose!(other, offset_x = 0, offset_y = 0) 57 check_size_constraints!(other, offset_x, offset_y) 58 59 for y in 0...other.height do 60 for x in 0...other.width do 61 set_pixel( 62 x + offset_x, 63 y + offset_y, 64 ChunkyPNG::Color.compose( 65 other.get_pixel(x, y), 66 get_pixel(x + offset_x, y + offset_y) 67 ) 68 ) 69 end 70 end 71 self 72 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 155 def crop(x, y, crop_width, crop_height) 156 dup.crop!(x, y, crop_width, crop_height) 157 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 175 def crop!(x, y, crop_width, crop_height) 176 if crop_width + x > width 177 raise ChunkyPNG::OutOfBounds, "Original image width is too small!" 178 end 179 if crop_height + y > height 180 raise ChunkyPNG::OutOfBounds, "Original image height is too small!" 181 end 182 183 if crop_width == width && x == 0 184 # We only need to crop off the top and/or bottom, so we can take a 185 # shortcut. 186 replace_canvas!(crop_width, crop_height, pixels.slice(y * width, width * crop_height)) 187 else 188 new_pixels = [] 189 for cy in 0...crop_height do 190 new_pixels.concat pixels.slice((cy + y) * width + x, crop_width) 191 end 192 replace_canvas!(crop_width, crop_height, new_pixels) 193 end 194 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 205 def flip_horizontally 206 dup.flip_horizontally! 207 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 218 def flip_horizontally! 219 for y in 0..((height - 1) >> 1) do 220 other_y = height - (y + 1) 221 other_row = row(other_y) 222 replace_row!(other_y, row(y)) 223 replace_row!(y, other_row) 224 end 225 self 226 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 240 def flip_vertically 241 dup.flip_vertically! 242 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 253 def flip_vertically! 254 for y in 0...height do 255 replace_row!(y, row(y).reverse) 256 end 257 self 258 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 36 def grayscale 37 dup.grayscale! 38 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 22 def grayscale! 23 pixels.map! { |pixel| ChunkyPNG::Color.to_grayscale(pixel) } 24 self 25 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 138 def replace(other, offset_x = 0, offset_y = 0) 139 dup.replace!(other, offset_x, offset_y) 140 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 111 def replace!(other, offset_x = 0, offset_y = 0) 112 check_size_constraints!(other, offset_x, offset_y) 113 114 for y in 0...other.height do 115 for d in 0...other.width 116 pixels[(y + offset_y) * width + offset_x + d] = other.pixels[y * other.width + d] 117 end 118 end 119 self 120 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 322 def rotate_180 323 dup.rotate_180! 324 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 330 def rotate_180! 331 pixels.reverse! 332 self 333 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 295 def rotate_left 296 dup.rotate_left! 297 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 306 def rotate_left! 307 new_pixels = [] 308 (width - 1).downto(0) { |i| new_pixels += column(i) } 309 replace_canvas!(height, width, new_pixels) 310 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 269 def rotate_right 270 dup.rotate_right! 271 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 279 def rotate_right! 280 new_pixels = [] 281 0.upto(width - 1) { |i| new_pixels += column(i).reverse } 282 replace_canvas!(height, width, new_pixels) 283 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 341 def trim(border = pixels.first) 342 dup.trim! 343 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 351 def trim!(border = pixels.first) 352 x1 = [*0...width].index { |c| column(c).uniq != [border] } 353 x2 = [*0...width].rindex { |c| column(c).uniq != [border] } 354 y1 = [*0...height].index { |r| row(r).uniq != [border] } 355 y2 = [*0...height].rindex { |r| row(r).uniq != [border] } 356 357 crop! x1, y1, x2 - x1 + 1, y2 - y1 + 1 358 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 395 def check_size_constraints!(other, offset_x, offset_y) 396 if width < other.width + offset_x 397 raise ChunkyPNG::OutOfBounds, "Background image width is too small!" 398 end 399 if height < other.height + offset_y 400 raise ChunkyPNG::OutOfBounds, "Background image height is too small!" 401 end 402 end