Class: SmartImage::JavaCanvas

Inherits:
BaseCanvas show all
Defined in:
lib/smart_image/java_canvas.rb

Overview

Canvas object backed by Java Graphics2D

Instance Method Summary collapse

Methods inherited from BaseCanvas

#destroyed?

Constructor Details

#initialize(width, height) ⇒ JavaCanvas

Returns a new instance of JavaCanvas.



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# File 'lib/smart_image/java_canvas.rb', line 12

def initialize(width, height)
  @width, @height = width, height
  @canvas = BufferedImage.new width, height, BufferedImage::TYPE_INT_ARGB
end

Instance Method Details

#alpha_mask(image_data, options = {}) ⇒ Object

Load the given file as an alpha mask for the image



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# File 'lib/smart_image/java_canvas.rb', line 40

def alpha_mask(image_data, options = {})
  input_stream = ByteArrayInputStream.new image_data.to_java_bytes
  mask = ImageIO.read input_stream
  
  width = mask.width
  image_data, mask_data = Java::int[width].new, Java::int[width].new
  
  mask.height.times do |y|
    # fetch a line of data from each image
    @canvas.get_rgb 0, y, width, 1, image_data, 0, 1
    mask.get_rgb 0, y, width, 1, mask_data, 0, 1
    
    width.times do |x|
      # mask away the alpha
      color = image_data[x] & 0x00FFFFFF 
      
      # turn red from the mask into alpha
      alpha = (mask_data[x] & 0x00FF0000) << 8 
      
      image_data[x] = color | alpha
    end
    
    @canvas.set_rgb 0, y, width, 1, image_data, 0, 1
  end
end

#composite(image_data, options = {}) ⇒ Object

Composite the given image data onto the canvas

Raises:



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# File 'lib/smart_image/java_canvas.rb', line 22

def composite(image_data, options = {})
  info = SmartImage.info image_data
  opts = {
    :width  => info.width,
    :height => info.height,
    :x => 0,
    :y => 0
  }.merge(options)
  
  input_stream = ByteArrayInputStream.new image_data.to_java_bytes
  image = ImageIO.read input_stream
  raise FormatError, "invalid image" unless image
  
  graphics = @canvas.graphics
  graphics.draw_image image, opts[:x], opts[:y], opts[:width], opts[:height], nil
end

#destroy ⇒ Object

Stub out destroy since Java actually garbage collects crap, unlike… C



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# File 'lib/smart_image/java_canvas.rb', line 18

def destroy
end

#encode(format, options = {}) ⇒ Object

Encode the image to the given format



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# File 'lib/smart_image/java_canvas.rb', line 67

def encode(format, options = {})
  case format
  when 'jpg'
    # If we're trying to save an JPEG, we need to convert it to RGB
    canvas = BufferedImage.new @width, @height, BufferedImage::TYPE_INT_RGB
    
    graphics = canvas.graphics
    graphics.draw_image @canvas, 0, 0, @width, @height, nil
  else
    canvas = @canvas
  end
  
  output_stream = ByteArrayOutputStream.new
  ImageIO.write(canvas, format, output_stream)
  String.from_java_bytes output_stream.to_byte_array
end