require 'tk'
require 'tkextlib/blt'

# left drag: expand
# left click: autoscale off
# right drag: shrink
# right click: autoscale on
# middle drag: move

class GraphBlt
  include Tk
  def initialize(width=300,height=300,w=nil,side="top")
    @graph = Tk::BLT::Graph.new(w, :width=>width,:height=>height).pack('side'=>side)
    @graph.axis_configure('x',:ticklength=>5)
    @graph.axis_configure('x',:showticks=>true)
    @graph.gridline_on()
    @graph.legend_configure( :hide=>'yes')
    @graph.crosshairs_configure( :hide=>'no')
    @graph.bind('1',proc{|x,y| box_start(x,y)},'%x %y')
    @graph.bind('B1-Motion',proc{|x,y| box_resize(x,y)},'%x %y')
    @graph.bind('ButtonRelease-1',proc{|x,y| enlarge(x,y)},'%x %y')
    @graph.bind('3',proc{|x,y| box_start(x,y)},'%x %y')
    @graph.bind('B3-Motion',proc{|x,y| box_resize(x,y)},'%x %y')
    @graph.bind('ButtonRelease-3',proc{|x,y| shrink(x,y)},'%x %y')
    @graph.bind('2',proc{|x,y| move_start(x,y)},'%x %y')
    @graph.bind('B2-Motion',proc{|x,y| move(x,y)},'%x %y')
    @graph.bind('ButtonRelease-2',proc{|x,y| },'%x %y')
    @xdata=Tk::BLT::Vector.new()
    @ydata=Tk::BLT::Vector.new()
    @plot = Tk::BLT::PlotComponent::Element.new(@graph, 'plot1', :label=>'foo')
    @plot.configure( :xdata=>@xdata, :ydata=>@ydata)
    @plot.configure( :linewidth=>1)
    @plot.configure( :symbol=>'none',:pixels=>5)
    @xb,@yb=nil,nil	#box
  end
  def add(x,y) # add new point
    @xdata.append(x)
    @ydata.append(y)
  end
  def xaxis(title)
    @graph.axis_configure('x',:title=>title)
  end
  def yaxis(title)
    @graph.title=title
#    @graph.axis_configure('y',:title=>title) # error on X
  end
  def mark=(symbol=true)
    symbols=["none","circle", "square", "diamond", "plus", "cross", 
             "splus", "scross", "triangle", "arrow"]
    s=case symbol
      when *symbols
        symbol
      when true
        "splus"
      else
        "none"
      end
    @plot.configure( :symbol=>s,:pixels=>5)
  end
  def box_start(x,y)
    @xb,@yb=@graph.invtransform(x,y)
    autoscale(false)
    xx,yy=@xb,@yb
    @graph.marker_create('line', :name=>'box',
                            :coords=>[@xb,@yb,@xb,yy,xx,yy,xx,@yb,@xb,@yb])
  end
  def box_resize(x,y)
    xx,yy=@graph.invtransform(x,y)
    @graph.marker_configure('box',
                            :coords=>[@xb,@yb,@xb,yy,xx,yy,xx,@yb,@xb,@yb])
  end
  def enlarge(x,y,x0=@xb,y0=@yb)
    @graph.marker_delete('box')
    xx,yy=@graph.invtransform(x,y)
    x0,xx=[x0,xx].sort
    y0,yy=[y0,yy].sort
    unless xx>x0 and yy>y0 # autoscale off
      x0,xx=@graph.xaxis_limits()
      y0,yy=@graph.yaxis_limits()
    end
    @graph.xaxis_configure(:min=>x0,:max=>xx)
    @graph.yaxis_configure(:min=>y0,:max=>yy)
  end
  def shrink(x,y,x1=@xb,y1=@yb)
    @graph.marker_delete('box')
    x0,xx=@graph.xaxis_limits()
    y0,yy=@graph.yaxis_limits()
    x2,y2=@graph.invtransform(x,y)
    x1,x2=[x1,x2].sort
    y1,y2=[y1,y2].sort
    if x2>x1 and y2>y1
      x0,xx=x0-(xx-x0)*(x1-x0)/(x2-x1),x0+(xx-x0)*(xx-x1)/(x2-x1)
      y0,yy=y0-(yy-y0)*(y1-y0)/(y2-y1),y0+(yy-y0)*(yy-y1)/(y2-y1)
      @graph.xaxis_configure(:min=>x0,:max=>xx)
      @graph.yaxis_configure(:min=>y0,:max=>yy)
    else # autoscale on
      autoscale()
    end
  end
  def move_start(x,y)
    @xb,@yb=x,y
    autoscale(false)
  end
  def move(x,y,x1=@xb,y1=@yb)
    @xb,@yb=x,y
    x,y=@graph.invtransform(x,y)
    x1,y1=@graph.invtransform(x1,y1)
    x0,xx=@graph.xaxis_limits()
    y0,yy=@graph.yaxis_limits()
    x0-=(x-x1)
    xx-=(x-x1)
    y0-=(y-y1)
    yy-=(y-y1)
    @graph.xaxis_configure(:min=>x0,:max=>xx)
    @graph.yaxis_configure(:min=>y0,:max=>yy)
  end
  def clear()
  end
  def autoscale(onoff=true)
    case onoff
    when true, "on", "ON"
      @graph.xaxis_configure(:min=>'',:max=>'')
      @graph.yaxis_configure(:min=>'',:max=>'')
    when false, "off", "OFF"
      x0,xx=@graph.xaxis_limits()
      y0,yy=@graph.yaxis_limits()
      @graph.xaxis_configure(:min=>x0,:max=>xx)
      @graph.yaxis_configure(:min=>y0,:max=>yy)
    end
  end

end #class

#2015.3.4 first version (expand,shrink,move)
#2015.3.11 bugfix