[julia-users] Hit test in Winston using Gtk

[Roger Herikstad]

Hi,
 I'm trying to implement a simple interface where I can click on points in 
a plot an get their (x,y) value. I was wondering how I can convert the 
(x,y) value returned by the Gtk mouse event to Winston data coordinates?

I am using this function to get a PlotContext from the GtkCanvas

function get_context(c::Gtk.Canvas, pc::Winston.PlotContainer)
    device = Winston.CairoRenderer(Gtk.cairo_surface(c))
    ext_bbox = Winston.BoundingBox(0,Winston.width(c),0,Winston.height(c))
    Winston._get_context(device, ext_bbox, pc)
end



 This is my interact function

function interact()
    c = Gtk.@Canvas()
    win = Gtk.@Window(c,"Test")
    p =  Winston.FramedPlot()
    Winston.plot(p,[1,2,3])
    display(c,p)
    Winston.show(c)

    function motion(w,event)
        cc = get_context(c, p)
        x, y = Winston.project(cc.geom, 1.0,1.0) # just testing what we can 
map from data to device coordinates
        println("$x, $y")
        x,y = Winston.device_to_data(cc,event.x,event.y)
        println("$xx, $yy")

    end
    c.mouse.button1press = motion
end 


           #I just copied this function from the Gtk implementation of 
Winston

function display(c::Gtk.Canvas, pc::Winston.PlotContainer)
    c.draw = let bad=false
        function (_)
            bad && return
            ctx = Winston.getgc(c)
            Winston.set_source_rgb(ctx, 1, 1, 1)
            Winston.paint(ctx)
            try
                Winston.page_compose(pc, Gtk.cairo_surface(c))
            catch e
                bad = true
                isa(e, WinstonException) || rethrow(e)
                println("Winston: ", e.msg)
            end
        end
    end
    Gtk.draw(c)
end 


The resulting (xx,yy) coordinates do not seem to correspond to the data 
coordinates that I'm clicking. Any thoughts on how to do this? Thanks!