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 175

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}'." if !args[:img]
  raise "No or invalid ':radius' given: '#{args}'." if !args[:radius].respond_to?("to_i") or args[:radius].to_i <= 0
  
  pic = args[:img]
  
  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 and x > 0 and 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
      
      #Make corners transparent.
      if false or RUBY_ENGINE == "jruby"
        #Make up for the fact that "get_pixels" has not been implemented in "rmagick4j"...
        pixels = []
        0.upto(y_to) do |count|
          pixels << Magick::Pixel.new(0, 0, 0, 255)
        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.opacity = Magick::TransparentOpacity
        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" and 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
  
  pic.matte = true
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 168

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