Re: Few more thoughts about arrowheads

[Lars Clausen <lars raeder dk>]

On Sun, 2005-05-22 at 20:07 +0200, Radek Krahl wrote:
> Hi all,
>
> Today i took a closer look at drawing previews of arrowheads in dia's
> main windows after recent addition of calculate_arrow_point to
> dia_arrow_preview_expose(). I have 'discovered' few problems.
>
> 1. Two arrows look the same now -- 'Hollow triangle' and 'Unfilled
> triangle'. There is one difference between them - first of them is drawn
> with triangle filled with background colour and second is drawn with
> hollow triangle.
> 2. After changing gtk theme to dark one: few arrowheads still use
> blanking with white together with 'line shortening': hollow-: -triangle,
> -diamond, -ellipse, -dot, -double triangle, -box, slashed, integral
> symbol (last two look the same for me, too). Lars said, that blanking is
> not a good way to draw arrows and additionally, i think,  getting rid of
> all that fill- and draw-with-background-color functions should speed up
> drawing of diagram a little.

Blanking is not a good way to remove parts of a line (see the integral
symbol, slashed and half diamond for examples), but makes sense inside
of a closed form.  While always using white for the blanking isn't
ideal, they both have reasonable uses, and there's no big reason to
remove them.  I doubt that their rendering is a significant time drain.

> So, my question is -- do you also see the sense of cleaning up arrow
> routines (removing drawing with background color)? I don't want to do
> anything that is unnecessary :).

Not in general, but using calculate_arrow_point instead of blanking for
integral symbol, slashed and half diamond may well work better than
blanking out a line.

> And second -- what to do with doubled arrows (i know that there can be a
> problem with back compatibility here), they look a little strange now.

The double arrows have some specific uses and should not be removed.

-Lars

-- 
Lars Clausen <lars raeder dk>