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 364 def border(size, color = ChunkyPNG::Color::BLACK) 365 dup.border!(size, color) 366 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 374 def border!(size, color = ChunkyPNG::Color::BLACK) 375 new_width = width + size * 2 376 new_height = height + size * 2 377 378 bg = Canvas.new(new_width, new_height, color).replace(self, size, size) 379 replace_canvas!(new_width, new_height, bg.pixels) 380 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 88 def compose(other, offset_x = 0, offset_y = 0) 89 dup.compose!(other, offset_x, offset_y) 90 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 54 def compose!(other, offset_x = 0, offset_y = 0) 55 check_size_constraints!(other, offset_x, offset_y) 56 57 for y in 0...other.height do 58 for x in 0...other.width do 59 set_pixel( 60 x + offset_x, 61 y + offset_y, 62 ChunkyPNG::Color.compose( 63 other.get_pixel(x, y), 64 get_pixel(x + offset_x, y + offset_y) 65 ) 66 ) 67 end 68 end 69 self 70 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 153 def crop(x, y, crop_width, crop_height) 154 dup.crop!(x, y, crop_width, crop_height) 155 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 173 def crop!(x, y, crop_width, crop_height) 174 if crop_width + x > width 175 raise ChunkyPNG::OutOfBounds, "Original image width is too small!" 176 end 177 if crop_height + y > height 178 raise ChunkyPNG::OutOfBounds, "Original image height is too small!" 179 end 180 181 if crop_width == width && x == 0 182 # We only need to crop off the top and/or bottom, so we can take a 183 # shortcut. 184 replace_canvas!(crop_width, crop_height, pixels.slice(y * width, width * crop_height)) 185 else 186 new_pixels = [] 187 for cy in 0...crop_height do 188 new_pixels.concat pixels.slice((cy + y) * width + x, crop_width) 189 end 190 replace_canvas!(crop_width, crop_height, new_pixels) 191 end 192 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 203 def flip_horizontally 204 dup.flip_horizontally! 205 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 216 def flip_horizontally! 217 for y in 0..((height - 1) >> 1) do 218 other_y = height - (y + 1) 219 other_row = row(other_y) 220 replace_row!(other_y, row(y)) 221 replace_row!(y, other_row) 222 end 223 self 224 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 238 def flip_vertically 239 dup.flip_vertically! 240 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 251 def flip_vertically! 252 for y in 0...height do 253 replace_row!(y, row(y).reverse) 254 end 255 self 256 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 34 def grayscale 35 dup.grayscale! 36 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 20 def grayscale! 21 pixels.map! { |pixel| ChunkyPNG::Color.to_grayscale(pixel) } 22 self 23 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 136 def replace(other, offset_x = 0, offset_y = 0) 137 dup.replace!(other, offset_x, offset_y) 138 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 109 def replace!(other, offset_x = 0, offset_y = 0) 110 check_size_constraints!(other, offset_x, offset_y) 111 112 for y in 0...other.height do 113 for d in 0...other.width 114 pixels[(y + offset_y) * width + offset_x + d] = other.pixels[y * other.width + d] 115 end 116 end 117 self 118 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 320 def rotate_180 321 dup.rotate_180! 322 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 328 def rotate_180! 329 pixels.reverse! 330 self 331 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 293 def rotate_left 294 dup.rotate_left! 295 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 304 def rotate_left! 305 new_pixels = [] 306 (width - 1).downto(0) { |i| new_pixels += column(i) } 307 replace_canvas!(height, width, new_pixels) 308 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 267 def rotate_right 268 dup.rotate_right! 269 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 277 def rotate_right! 278 new_pixels = [] 279 0.upto(width - 1) { |i| new_pixels += column(i).reverse } 280 replace_canvas!(height, width, new_pixels) 281 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 339 def trim(border = pixels.first) 340 dup.trim! 341 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 349 def trim!(border = pixels.first) 350 x1 = [*0...width].index { |c| column(c).uniq != [border] } 351 x2 = [*0...width].rindex { |c| column(c).uniq != [border] } 352 y1 = [*0...height].index { |r| row(r).uniq != [border] } 353 y2 = [*0...height].rindex { |r| row(r).uniq != [border] } 354 355 crop! x1, y1, x2 - x1 + 1, y2 - y1 + 1 356 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 393 def check_size_constraints!(other, offset_x, offset_y) 394 if width < other.width + offset_x 395 raise ChunkyPNG::OutOfBounds, "Background image width is too small!" 396 end 397 if height < other.height + offset_y 398 raise ChunkyPNG::OutOfBounds, "Background image height is too small!" 399 end 400 end