ledsign_text_renderer

#!/opt/local/bin/ruby1.9
require 'sinatra'
require 'cairo'
require 'pango'
require 'bmix'
# set :port, 9494

ALIGN={"center"=>Pango::ALIGN_CENTER,"left"=>Pango::ALIGN_LEFT,"right"=>Pango::ALIGN_RIGHT}

def get_resized_font_size(surface, layout, font_name, font_size, font_min_size)
  font_desired_size = font_size
  fontdesc = Pango::FontDescription.new("#{font_name} #{font_size}")
  layout.set_font_description fontdesc
  while(layout.pixel_extents[1].width > surface.width \
     || layout.pixel_extents[1].height > surface.height) do
    font_size -= 1
    fontdesc.set_size font_size * Pango::SCALE
    layout.set_font_description fontdesc
    if(font_size < font_min_size) then
      # we can't render this much text big enough to be readable
      # set the font size back to what we were given originally and give up
      font_size = font_desired_size
      fontdesc.set_size font_size * Pango::SCALE
      layout.set_font_description fontdesc
      return -1
    end
  end
  font_size
end

def scroll_text(surface, ctx, layout, voffset, bmix)
  left = 0
  frame = 0
  sleep_time = 0.025
  step = 2
  layout.set_width -1 # don't wrap if we're scrolling
  scroll_seconds = (layout.pixel_extents[1].width + surface.width) / step * sleep_time
  while(scroll_seconds > 8) do
    scroll_seconds = (layout.pixel_extents[1].width + surface.width) / step * sleep_time
    step += 1
  end
  puts "Expecting to scroll text for #{scroll_seconds} seconds using step #{step}."
  while(layout.pixel_extents[1].width + left >= surface.width - 3) do
    frame += 1
    ctx.move_to left, voffset
    ctx.set_source_color(:black)
    ctx.paint
    ctx.set_source_color(:white)
    ctx.show_pango_layout layout
    bmix.send_frame surface
    sleep 0.025
    left -= step
  end
  return "Successfully rendered #{frame} frames of scrolling text."
end

get '/signservice/SignService' do
  msg = params[:Message] || "Get Ready For A Whole Bunch of Ostriches and Cats"
  wrap = params[:WrapMethod] || 'best'
  font_name = params[:FontName] || "Sans"
  font_size_str = params[:FontSize] || "12"
  font_size = font_size_str.to_i
  font_min_size_str = params[:FontMinSize] || "6"
  font_min_size = font_min_size_str.to_i
  alignment = ALIGN["center"]
  text_align = params[:Align] || "center"
  alignment = ALIGN[text_align] if ALIGN.has_key?text_align
  port_str = params[:Port] || "2324"
  port = port_str.to_i
  voffset_str = params[:VOffset] || "0"
  voffset = voffset_str.to_i
  bmix = Bmix::Sender.new("sign0.hacklab.to",port)

  surface = Cairo::ImageSurface.new(Cairo::Format::ARGB32, 96, 32)
  ctx = Cairo::Context.new(surface)
  ctx.set_source_color(:white)

  layout = ctx.create_pango_layout
  ctx.move_to 0,voffset
  # puts "MSG: #{msg}"
  layout.set_text(msg)
  fontdesc = Pango::FontDescription.new("#{font_name} #{font_size}")
  layout.set_font_description fontdesc
  case wrap
    when 'wrap'
      layout.set_wrap(Pango::WRAP_WORD)
    when 'resize'
      layout.set_width surface.width * Pango::SCALE
      font_size = get_resized_font_size(surface, layout, font_name, font_size, font_min_size)
      if(font_size < 0) then
        return "Unable to render #{msg.length} characters of text in a readable font."
      end
      fontdesc = Pango::FontDescription.new("#{font_name} #{font_size}")
      layout.set_font_description fontdesc      
    when 'best'
      # try to resize the text to fit, if it won't fit then scroll it
      layout.set_width surface.width * Pango::SCALE
      font_size = get_resized_font_size(surface, layout, font_name, font_size, font_min_size)
      if(font_size < 0) then
        return scroll_text surface, ctx, layout, voffset, bmix
      end
      fontdesc = Pango::FontDescription.new("#{font_name} #{font_size}")
      layout.set_font_description fontdesc      
    when 'scroll'
      return scroll_text surface, ctx, layout, voffset, bmix
  end
  layout.set_width surface.width * Pango::SCALE  
  layout.set_alignment alignment

  ctx.show_pango_layout layout

  bmix.send_frame surface
  "Successfully rendered #{msg.length} characters to the sign in size #{font_size} using wrap method '#{wrap}'. Extents are #{layout.pixel_extents[1].width} x #{layout.pixel_extents[1].height}."
end