M
Michael Neumann
The component! For example the button component has to draw itself onto
the screen, for which it needs a canvas.
Well, my example above was not good choosen. Better would have been:
class Button < Component
# this one is called from 'outside'
def draw_on(canvas)
draw_frame(canvas)
draw_inner(canvas)
end
private
# helper method
def draw_frame(canvas)
if @pressed
canvas.color = :lightgray
canvas.line(x, y, x+w, y)
canvas.line(x+w, y, x+w, y+h)
...
else
...
end
end
# helper method
def draw_inner(canvas)
canvas.text(@caption)
end
end
Of course the canvas implements the drawing primitives.
Now think the same for the Web and Html generation.
If I were the renderer, I'd have a headache from all the knowledge that
you must have stuffed into my poor brainThere must be a better way
to do this.
Hm, but somewhere you have to implement how the component looks like, no?
The above is equivalent to:
cgi.table {
cgi.tr {
cgi.td { ... } +
cgi.td { ... }
}
}
But in a more imperatively fashion, similar as for drawing a GUI on the
canvas, where you don't do this ('+'):
canvas.box(...) {
canvas.line(1, 1, 10, 10) +
canvas.line(...) +
...
}
Regards,
Michael