Class: Knj::Image

Inherits:
Object show all
Defined in:
lib/knj/image.rb

Overview

This class holds methods to manipulate images.

Class Method Summary collapse

Class Method Details

.height_for_width(orig_width, orig_height, new_width) ⇒ Object

Returns the height relative to the width.

Examples

Knj::Image.height_for_width(640, 480, 533) #=> 399



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# File 'lib/knj/image.rb', line 174

def self.height_for_width(orig_width, orig_height, new_width)
  return (orig_height.to_f / (orig_width.to_f / new_width.to_f)).to_i
end

.rounded_corners(args) ⇒ Object

This function can make rounded transparent corners on an image with a given radius. Further more it can also draw borders around the entire image in a given color and take the border into account.

Examples

img = Magick::Image.read(path_str) Knj::Image.rounded_corners(

img: img,
radius: 25,
border: 1,
border_color: "#000000"

)



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# File 'lib/knj/image.rb', line 12

def self.rounded_corners(args)
  raise "No or invalid ':img' given: '#{args}'." unless args[:img]
  raise "No or invalid ':radius' given: '#{args}'." if !args[:radius].respond_to?(:to_i) || args[:radius].to_i <= 0

  pic = args[:img]
  raise "Format '#{pic.format}' does not support transparency." if pic.format == "JPEG"

  r = args[:radius].to_i
  r_half = r / 2
  r2 = r * r
  d = r * 2

  center_x = r - 1
  center_y = 1

  coords = {}
  0.upto(r) do |x|
    y = center_y + ::Math.sqrt(r2 - ((x - center_x) * (x - center_x)))
    coords[x] = y.to_i
  end

  if args[:border]
    draw = ::Magick::Draw.new
    draw.stroke(args[:border_color])
    draw.stroke_width(1)

    0.upto(args[:border] - 1) do |x|
      draw.line(x, 0, x, pic.rows)
      draw.line(pic.columns-x-1, 0, pic.columns-x-1, pic.rows)

      draw.line(0, x, pic.columns, x)
      draw.line(0, pic.rows-x-1, pic.columns, pic.rows-x-1)
    end

    draw.draw(pic)
  end

  borders = [] if args[:border]

  1.upto(4) do |count|
    r.times do |x|
      border_from = nil
      border_to = nil
      border_mode = nil

      case count
        when 1
          x_from = x

          y_from = 0
          y_to = r - coords[x]

          if borders && x > 0 && x < r_half
            border_from = y_to
            border_to = r - coords[x - 1]
            border_to = 1 if border_to < 1

            #top left
            borders << {x: x_from, yf: border_from, yt: border_to}
            borders << {y: x_from, xf: border_from, xt: border_to}

            #top right
            borders << {x: pic.columns - x - 1, yf: border_from, yt: border_to}
            borders << {y: x_from, xf: pic.columns - border_to, xt: pic.columns - border_from}

            #bottom left
            borders << {x: x_from, yf: pic.rows - border_to, yt: pic.rows - border_from}
            borders << {y: pic.rows - x - 1, xf: border_from, xt: border_to}

            #bottom right
            borders << {x: pic.columns - x - 1, yf: pic.rows - border_to, yt: pic.rows - border_from}
            borders << {y: pic.rows - x - 1, xf: pic.columns - border_to, xt: pic.columns - border_from}
          end
        when 2
          x_from = pic.columns - r + x

          y_from = 0
          y_to = r - coords[r - x - 1]
        when 3
          x_from = x

          y_from = pic.rows - r + coords[x]
          y_to = pic.rows - y_from
        when 4
          x_from = pic.columns - r + x

          y_from = pic.rows - r + coords[r - x - 1]
          y_to = pic.rows - y_from
      end

      next if y_to <= 0

      if RUBY_ENGINE == "jruby"
        # Hack around missing method in rmagick4j Image#get_pixels. It will be black :-(
        pixels = []
        y_to.times do |count|
          pixel = Magick::Pixel.new(0, 0, 0, 255)
          pixels << pixel
        end

        pic.store_pixels(x_from, y_from, 1, y_to, pixels)
      else
        pixels = pic.get_pixels(x_from, y_from, 1, y_to)
        pixels.each do |pixel|
          pixel.alpha = ::Magick::QuantumRange
        end
        pic.store_pixels(x_from, y_from, 1, y_to, pixels)
      end
    end
  end

  if borders
    color = args[:border_color]

    borders.each do |border|
      if border.key?(:x)
        count_from = border[:yf]
        count_to = border[:yt]
      elsif border.key?(:y)
        count_from = border[:xf]
        count_to = border[:xt]
      end

      count_from.upto(count_to - 1) do |coord|
        if RUBY_ENGINE == "jruby" && color[0, 1] == "#"
          r = color[1, 2].hex
          b = color[3, 2].hex
          g = color[5, 2].hex

          pixel = ::Magick::Pixel.new(r, b, g)
        else
          pixel = ::Magick::Pixel.from_color(color)
        end

        if border.key?(:x)
          if RUBY_ENGINE == "jruby"
            pic.store_pixels(border[:x], coord, 1, 1, [pixel])
          else
            pic.pixel_color(border[:x], coord, pixel)
          end
        elsif border.key?(:y)
          if RUBY_ENGINE == "jruby"
            pic.store_pixels(coord, border[:y], 1, 1, [pixel])
          else
            pic.pixel_color(coord, border[:y], pixel)
          end
        end
      end
    end
  end
end

.width_for_height(orig_width, orig_height, new_height) ⇒ Object

Returns the width relative to the height.

Examples

Knj::Image.width_for_height(640, 480, 400) #=> 533



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# File 'lib/knj/image.rb', line 167

def self.width_for_height(orig_width, orig_height, new_height)
  return (orig_width.to_f / (orig_height.to_f / new_height.to_f)).to_i
end