Module: ChunkyPNG::Canvas::Operations

### Home Classes Methods

### In Files

- lib/chunky_png/canvas/operations.rb

### Methods

- #border
- #border!
- #check_size_constraints!
- #compose
- #compose!
- #crop
- #crop!
- #flip
- #flip!
- #flip_horizontally
- #flip_horizontally!
- #flip_vertically
- #flip_vertically!
- #grayscale
- #grayscale!
- #mirror
- #mirror!
- #replace
- #replace!
- #rotate_180
- #rotate_180!
- #rotate_clockwise
- #rotate_clockwise!
- #rotate_counter_clockwise
- #rotate_counter_clockwise!
- #rotate_left
- #rotate_left!
- #rotate_right
- #rotate_right!
- #trim
- #trim!

### Files

- BENCHMARKING.rdoc
- CHANGELOG.rdoc
- CONTRIBUTING.rdoc
- README.rdoc

### Class/Module Index

Quicksearch

- ChunkyPNG
- ChunkyPNG::CRCMismatch
- ChunkyPNG::Canvas
- ChunkyPNG::Canvas::Adam7Interlacing
- ChunkyPNG::Canvas::DataUrlExporting
- ChunkyPNG::Canvas::DataUrlImporting
- ChunkyPNG::Canvas::Drawing
- ChunkyPNG::Canvas::Masking
- ChunkyPNG::Canvas::Operations
- ChunkyPNG::Canvas::PNGDecoding
- ChunkyPNG::Canvas::PNGEncoding
- ChunkyPNG::Canvas::Resampling
- ChunkyPNG::Canvas::StreamExporting
- ChunkyPNG::Canvas::StreamImporting
- ChunkyPNG::Chunk
- ChunkyPNG::Chunk::Base
- ChunkyPNG::Chunk::CompressedText
- ChunkyPNG::Chunk::End
- ChunkyPNG::Chunk::Generic
- ChunkyPNG::Chunk::Header
- ChunkyPNG::Chunk::ImageData
- ChunkyPNG::Chunk::InternationalText
- ChunkyPNG::Chunk::Palette
- ChunkyPNG::Chunk::Text
- ChunkyPNG::Chunk::Transparency
- ChunkyPNG::Color
- ChunkyPNG::Datastream
- ChunkyPNG::Dimension
- ChunkyPNG::Exception
- ChunkyPNG::ExpectationFailed
- ChunkyPNG::Image
- ChunkyPNG::NotSupported
- ChunkyPNG::OutOfBounds
- ChunkyPNG::Palette
- ChunkyPNG::Point
- ChunkyPNG::RMagick
- ChunkyPNG::SignatureMismatch
- ChunkyPNG::Vector
- Enumerable
- String

No matching classes.

# 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

border(size, color = ChunkyPNG::Color::BLACK) click to toggle source

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 356
    def border(size, color = ChunkyPNG::Color::BLACK)
      dup.border!(size, color)
    end

border!(size, color = ChunkyPNG::Color::BLACK) click to toggle source

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 366
    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

compose(other, offset_x = 0, offset_y = 0) click to toggle source

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 85
    def compose(other, offset_x = 0, offset_y = 0)
      dup.compose!(other, offset_x, offset_y)
    end

compose!(other, offset_x = 0, offset_y = 0) click to toggle source

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

    # 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

crop(x, y, crop_width, crop_height) click to toggle source

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 150
    def crop(x, y, crop_width, crop_height)
      dup.crop!(x, y, crop_width, crop_height)
    end

crop!(x, y, crop_width, crop_height) click to toggle source

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 170
    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

      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

flip() click to toggle source
Alias for: flip_horizontally
flip!() click to toggle source
Alias for: flip_horizontally!
flip_horizontally() click to toggle source

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 194
    def flip_horizontally
      dup.flip_horizontally!
    end

Also aliased as: flip
flip_horizontally!() click to toggle source

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 207
    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

Also aliased as: flip!
flip_vertically() click to toggle source

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 229
    def flip_vertically
      dup.flip_vertically!
    end

Also aliased as: mirror
flip_vertically!() click to toggle source

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 242
    def flip_vertically!
      for y in 0...height do
        replace_row!(y, row(y).reverse)
      end
      self
    end

Also aliased as: mirror!
grayscale() click to toggle source

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 34
    def grayscale
      dup.grayscale!
    end

grayscale!() click to toggle source

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 20
    def grayscale!
      pixels.map! { |pixel| ChunkyPNG::Color.to_grayscale(pixel) }
      self
    end

mirror() click to toggle source
Alias for: flip_vertically
mirror!() click to toggle source
Alias for: flip_vertically!
replace(other, offset_x = 0, offset_y = 0) click to toggle source

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 133
    def replace(other, offset_x = 0, offset_y = 0)
      dup.replace!(other, offset_x, offset_y)
    end

replace!(other, offset_x = 0, offset_y = 0) click to toggle source

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

    # File lib/chunky_png/canvas/operations.rb, line 106
    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

rotate_180() click to toggle source

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 312
    def rotate_180
      dup.rotate_180!
    end

rotate_180!() click to toggle source

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 320
    def rotate_180!
      pixels.reverse!
      self
    end

rotate_clockwise() click to toggle source
Alias for: rotate_right
rotate_clockwise!() click to toggle source
Alias for: rotate_right!
rotate_counter_clockwise() click to toggle source
Alias for: rotate_left
rotate_counter_clockwise!() click to toggle source
Alias for: rotate_left!
rotate_left() click to toggle source

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 285
    def rotate_left
      dup.rotate_left!
    end

Also aliased as: rotate_counter_clockwise
rotate_left!() click to toggle source

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 296
    def rotate_left!
      new_pixels = []
      (width - 1).downto(0) { |i| new_pixels += column(i) }
      replace_canvas!(height, width, new_pixels)
    end

Also aliased as: rotate_counter_clockwise!
rotate_right() click to toggle source

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 258
    def rotate_right
      dup.rotate_right!
    end

Also aliased as: rotate_clockwise
rotate_right!() click to toggle source

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 268
    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

Also aliased as: rotate_clockwise!
trim(border = pixels.first) click to toggle source

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 331
    def trim(border = pixels.first)
      dup.trim!
    end

trim!(border = pixels.first) click to toggle source

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 341
    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

check_size_constraints!(other, offset_x, offset_y) click to toggle source

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 385
    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

[Validate]

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