Class: DynamicImageSources::GradientSource

Inherits:
SourceFactory show all
Defined in:
lib/sources/gradient_source.rb

Overview

Source providing gradient source to drawing.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(type, ext, *args) ⇒ GradientSource

Creates gradient source object from type and extend type.

Valid values for type are :linear and :radial. Default is :linear.

Valid values for extend type are :pad, :repeat and :reflect. Default is :pad.



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# File 'lib/sources/gradient_source.rb', line 13

def initialize(type, ext, *args)
  @type = type || :linear
  @ext = ext || :pad
  @args = args
  @stops = []
end

Class Method Details

.parse(source) ⇒ Object

Returns source object or nil if it can’t parse it.

Supported syntax

All values can be given as Array or String separated by space chars.

Values has to be in this order: [:gradient_name, *gradient_arguments, stop_value1, stop_value2, ..., stop_valueN]. All values has to be in one-dimensional array.

Gradient name

Valid gradient names are:

  • Linear:

    • :gradient for linear gradient

    • :gradient_repeat for linear gradient with repeating

    • :gradient_reflect for linear gradient with reflection

  • Radial:

    • :gradient_radial for radial gradient

    • :gradient_radial_repeat for radial gradient with repeating

    • :gradient_radial_reflect for radial gradient with reflection

Gradient arguments

Gradient arguments are different for linear and radial gradients. Adding gradient options is optional.

Linear

Valid values are [x0, y0, x1, y1] or [angle, size] where size is optional.

At first place x0, y0 locates first and x1, y1 second points of gradient vector in pixels.

At second place angle defines direction of gradient from top left corner. Valid values are 0deg - 360deg (“deg” must be included). Default is 0deg meaning East. Angle is counted in clockwise direction.

Size is a length of gradinet vector. You can use percentage. F.e.: "50%".

Radial

Valid values are [x0, y0, r0, x1, y1, r1] or [size, angle0, dif0, angle1, dif1] where size and pair angle1, dif1 are optional.

At first place x0, y0 locates first and x1, y1 second centers of circles and r0, r1 theirs radius. All in pixels.

At second place size is a length of gradinet vector. You can use percentage. F.e.: "50%".

Angle and dif defines direction and value of circle movement. Valid values for angle are 0deg - 360deg (“deg” must be included). Default is 0deg meaning East. Angle is counted in clockwise direction. You can use percentage for dif. F.e.: "50%".

Stop values

Stop is described as offset value at first position followed by color. The offset specifies the location in % along the gradient’s control vector. For color see ColorSource.parse.

Example

  • [:gradient, "0%", :red, "100%", :blue] will create linear gradient red at left side and blue at right side

  • [:gradient, "0%", 1, 0, 0, "100%", 0, 0, 1] same as above

  • [:gradient_reflect, "50%", "0%", 1, 0, 0, "100%", 0, 0, 1] will create gradient red at left side, blue in middle and red at right side

  • [:gradient, "90deg", "0%", :red, "100%", :blue] will create linear gradient red at top and blue at bottom

  • [:gradient_radial, "0%", :red, "100%", :blue] will create radial gradient red in center and blue at sides

  • [:gradient_radial, 100, "0%", :red, "100%", :blue] will create radial gradient red in center and blue 100px from center

  • [:gradient_radial, "225deg", "50%", "0%", :red, "100%", :blue]will create radial gradient red in left top quadrant and blue at sides



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# File 'lib/sources/gradient_source.rb', line 72

def self.parse(source)
  if source[0].to_s.downcase =~ /\Agradient_?(radial)?_?(reflect|repeat)?\Z/
    ext = $2
    source.shift
    unless $1 #linear
      if source[0..3].join(' ') =~ /\A(\d+) (\d+) (\d+) (\d+)\Z/ # x0, y0, x1, y1
        args = [$1, $2, $3, $4].map(&:to_i)
        source.shift 4
      else # angle deg, [size (%)]
        args = [0, 1.0]
        if source.first.to_s =~ /\A\d+deg\Z/ #angle
          args[0] = source.first.to_i
          source.shift
        end
        if source.first.to_s =~ /\A\d+\Z/ #size
          args[1] = source.first.to_i
          source.shift
        end
        if source[1].to_s =~ /\A\d+%\Z/ && source.first.to_s =~ /\A(\d+)%\Z/ # size
          args[1] = $1.to_f/100.0
          source.shift
        end
      end
      object = new :linear, ext, *args
    else #radial
      # Args => [size (%),] [angle1 deg, dif1 (%), [angle2 deg, dif2 (%)]]
      if source[0..5].join(' ') =~ /\A(\d+) (\d+) (\d+) (\d+) (\d+) (\d+)\Z/ # x0, y0, d0, x1, y1, d1
        args = [$1, $2, $3, $4, $5, $6].map(&:to_i)
        source.shift 6
      else
        args = [1.0, 0, 0, 0, 0]
        if source.first.to_s =~ /\A\d+\Z/ #size
          args[0] = source.first.to_i
          source.shift
        end
        if source[1].to_s =~ /\A\d+(%|deg)\Z/ && source.first.to_s =~ /\A(\d+)%\Z/ # size
          args[0] = $1.to_f/100.0
          source.shift
        end
        if source[0..1].join(' ') =~ /\A(\d+)deg (\d+)(%)?\Z/ # angle1 deg, dif1 (%)
          args[1] = $1.to_i
          args[2] = $3 ? $2.to_f/100.0 : $2.to_i
          source.shift 2
        end
        if source[0..1].join(' ') =~ /\A(\d+)deg (\d+)(%)?\Z/ # angle2 deg, dif2 (%)
          args[3] = $1.to_i
          args[4] = $3 ? $2.to_f/100.0 : $2.to_i
          source.shift 2
        end
      end
      object = new :radial, ext, *args
    end
    stops = []
    source.each do |i|
      if i.to_s =~ /(\d+)%/
        stops << [$1.to_f/100.0]
      else
        stops.last << i if stops.last
      end
    end
    stops.each do |stop|
      color = ColorSource.parse(stop[1..-1])
      return nil unless color
      object.send :add_stop, stop.first, color
    end
    object
  end
end

Instance Method Details

#set_source(context, x, y, w, h) ⇒ Object

Sets color as source to given context



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# File 'lib/sources/gradient_source.rb', line 142

def set_source(context, x, y, w, h)
  case @type.to_sym
  when :linear
    if @args.size == 4
      pattern = Cairo::LinearPattern.new @args[0]+x, @args[1]+y, @args[2]+x, @args[3]+y
    else
      if @args[1].class == Float
        deg = (@args[0]%180+180)%180
        deg = 180 - deg if deg > 90
        deg *= Math::PI / 180
        deg -= Math.atan(h.to_f/w.to_f)
        dist = Math.sqrt(w**2 + h**2) * Math.cos(deg)
        dist = dist * @args[1]
      else
        dist = @args[1]
      end
      pattern = Cairo::LinearPattern.new *[x, y, degree_dist(@args[0], dist, x, y)].flatten
    end
  when :radial
    if @args.size == 6
      pattern = Cairo::RadialPattern.new @args[0]+x, @args[1]+y, @args[2], @args[3]+x, @args[4]+y, @args[5]
    else
      x, y = [x+w/2, y+h/2]
      radius = @args[0].class == Float ? Math.sqrt(w**2 + h**2)/2 * @args[0] : @args[0]
      dist1 = @args[2].class == Float ? radius * @args[2] : @args[2]
      dist2 = @args[4].class == Float ? radius * @args[4] : @args[4]
      pattern = Cairo::RadialPattern.new *[degree_dist(@args[1], dist1, x, y), 0, degree_dist(@args[3], dist2, x, y), radius].flatten
    end
  end
  pattern.set_extend({
    :pad => Cairo::EXTEND_NONE,
    :repeat => Cairo::EXTEND_REPEAT,
    :reflect => Cairo::EXTEND_REFLECT
  }[@ext.to_sym]) unless @type.to_sym == :radial && @ext.to_sym == :pad
  @stops.each do |stop|
    pattern.add_color_stop_rgba *stop
  end

  context.set_source pattern
  context.fill_preserve
end