README.md

rectangle.maker.rb

Sample rectangle-making code. Presented at The Dalvik Underground, April 7, 2014.

Questions? Get in touch.

rectangle-maker.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'chunky_png'

# the resolutions we care about
sizes = {
  mdpi: 1.0,
  hdpi: 1.5,
  xhdpi: 2.0,
  xxhdpi: 3.0
}

# the colors we'll use
PRESSED_HOLO_LIGHT = ChunkyPNG::Color.rgba(51, 181, 229, 153)
TRANSPARENT = ChunkyPNG::Color::TRANSPARENT
BLACK = ChunkyPNG::Color::BLACK
WHITE = ChunkyPNG::Color::WHITE
GREY = ChunkyPNG::Color.rgb(221, 221, 221)
REDDISH = ChunkyPNG::Color.rgb(0xd5, 0x30, 0x49)

def pressed(bg)
  ChunkyPNG::Color.compose_precise(PRESSED_HOLO_LIGHT, bg)
end

module CanvasExtras
  # like ChunkyPNG::Drawing::rect, but sets pixels instead of composing them.
  def force_rect(x0, y0, x1, y1, fill_color = ChunkyPNG::Color::TRANSPARENT)
    [x0, x1].min.upto([x0, x1].max) do |x|
      [y0, y1].min.upto([y0, y1].max) do |y|
        set_pixel(x, y, fill_color)
      end
    end
  end
end

ChunkyPNG::Canvas.send :include, CanvasExtras

class Array
  def sum
    self.inject(0){ |a,b| a+b }
  end
end

shapes = {
  standalone: [ true, true ],
  top: [ true, false ],
  top_dark: [ true, false ],
  bottom: [ false, true ],
  middle: [ false, false ]
}

modes = {
  resting: WHITE,
  pressed: pressed(WHITE),
  focused: ChunkyPNG::Color.rgb(193, 232, 247)
}

sizes.each do |dpi, factor|
  shapes.each do |shape, args|

    draw_top = args[0]
    draw_bottom = args[1]

    # set up the bounds, working in dip
    left_to_right = [15, 1, 15, 4, 15, 1, 15]
    top_to_bottom = [8, 1, 8, 4, 8, 1, 8]

    unless draw_top
      top_to_bottom[0] = 0
      top_to_bottom[1] = 0
    end
    unless draw_bottom
      top_to_bottom[6] = 0
    end

    # convert dip to px. 9-patch borders are always 1px.
    scaled_left_to_right = [1] + left_to_right.map{|n| (n*factor).round} + [1]
    scaled_top_to_bottom = [1] + top_to_bottom.map{|n| (n*factor).round} + [1]

    # hairlines are also always 1px.
    scaled_left_to_right[2] = scaled_left_to_right[6] = 1
    scaled_top_to_bottom[6] = 1 unless shape == :top_dark
    scaled_top_to_bottom[2] = 1 if draw_top

    width = scaled_left_to_right.sum
    height = scaled_top_to_bottom.sum

    puts "#{dpi} #{shape}: #{width}x#{height}"
    modes.each do |mode, maincolor|
      colors = [TRANSPARENT, GREY, maincolor]
      png = ChunkyPNG::Image.new(width, height, TRANSPARENT)

      0.upto(2) do |i|
        left = scaled_left_to_right[0..i].sum
        right = scaled_left_to_right[0..(7-i)].sum - 1
        top = scaled_top_to_bottom[0..i].sum
        bottom = scaled_top_to_bottom[0..(7-i)].sum - 1
        png.force_rect(left, top, right, bottom, colors[i])
      end

      unless draw_bottom
        left = scaled_left_to_right[0..2].sum
        right = scaled_left_to_right[0..5].sum - 1
        top = scaled_top_to_bottom[0..5].sum
        bottom = scaled_top_to_bottom[0..6].sum - 1
        png.force_rect(left, top, right, bottom, WHITE)

        left = scaled_left_to_right[0..3].sum
        right = scaled_left_to_right[0..4].sum - 1
        png.rect(left, top, right, bottom, (shape == :top_dark ? REDDISH : GREY))
      end

      left = scaled_left_to_right[0..3].sum
      right = scaled_left_to_right[0..4].sum - 1
      top = scaled_top_to_bottom[0..3].sum
      bottom = scaled_top_to_bottom[0..4].sum - 1

      png.line(left, 0, right, 0, BLACK)
      png.line(left, height-1, right, height-1, BLACK)
      png.line(0, top, 0, bottom, BLACK)
      png.line(width-1, top, width-1, bottom, BLACK)
      fn = File.join(File.dirname(__FILE__), "..", "res", "drawable-#{dpi}", "venuepicker_#{shape}_#{mode}.9.png")
      png.save(fn)
    end
  end
end