Re: @Diag question

[Mark Summerfield]

On 2008-09-02, j. van den hoff wrote:
> Jeff Kingston <jeff <at> it.usyd.edu.au> writes:
> > > I was not able to find out how to freely position start and
> > > end point of links on the object boundary in @Diag.
> >
> > Sounds like you need a bit of algebra, as in Section 9.11 of
> > the User's Guide.
> >
> > > I tried verbatim the example on page 209 of the manual, ...
> > > this does _not_ produce the diagram as in the manual.
> >
> > It's all a question of how much space is made available to
> > the diagram by its context.  If you had used @CD @Diag ...
> > instead of @Diag ... for example, you would have got what
> > you see in the manual, because only the minimum amount of
> > horizontal space is made available to a centred display.
> > Lout is basically keen to give as much space as possible
> > to everything, on the principle that it is easy to elec
> > not to use it if you don't want it.
> >
> > Jeff
>
> thanks for this explanation. this (the necessity for @CD) was not obvious
> to a beginner (me, anyway)
> from the context of the example. maybe a remark could be added to the
> manual (which is overall very good, by the way!)? --
>
> concerning my initial aim of drawing two (three, four, ...) boxes aligned
> on a "grid" and connected by 'off-center' arrows like this:
>
>      ______   k1 ______
>
>      |    | ---->|    |
>      |
>      | c1 |      | c2 |   ,
>      |
>      |    | <----|    |
>
>      ------   k2 ------
>
> I'm still not happy. using low level alignment with white space like this:
>
> @CD
> @Diag vsize {5f} hsize {5f} arrowwidth {.5f}
> margin {0f}
> {
> A::@Box
> address@hidden {c sub 1}}
> &5f
> B::@Box address@hidden {c sub 2}}
>
> C::@Box address@hidden {c sub 3 = k sub 3 cdot int from 0 to t c sub 2 }}
>
> @Line from address@hidden 1.25f}} to address@hidden 1.25f}}
>    ylabel address@hidden  {K sub 1}}
> @Arrow from address@hidden 1.25f}} to address@hidden 1.25f}}
>
> @Line from address@hidden 1.25f}} to address@hidden 1.25f}}
>    ylabelprox {below}
>    ylabel address@hidden  {k sub 2}}
> @Arrow from address@hidden 1.25f}} to address@hidden 1.25f}}
>
> }
>
> worked OK. I only noted that th `ylabel' on an arrow is not centered on the
> arrow as a whole but rather on the line excluding the arrowhead. this
> necessitates the awkward double drawing of lines (with labels) and arrows
> to get the vertical alignment of k1 and k2 right. question: is this as it
> should be or am I missing something?
>
> but trying to actually use the positioning scheme proposed in the manual I
> ended up with (positions of arrows are not the same as above
> intentionally):
>
> @CD @Diag
> margin {0c} arrowwidth {.5f}
>
> {
>
> 6c @Wide 2c @High
> //
> A:: @Box
>    translate { W to 0, 0.5 }
>    2c @Wide 2c @High
>    { @CD @Eq { c sub 1 } }
>
> B:: @Box
>    translate { E to 1, 0.5 }
>    2c @Wide 2c @High
>    { @CD @Eq { c sub 2 } }
>
> @Arrow from address@hidden 0.333c}} to address@hidden 0.333c}}
> ylabel address@hidden  {K sub 1}}
> @Arrow from address@hidden 0.333c}} to address@hidden 0.333c}}
> ylabel address@hidden  {k sub 2}}
>
> (note that here the arrow labels are actually not aligned as already noted
> above). what's more of a problem to me is that now the boxed text is no
> longer centered in the boxes. question: how do I do this right?
>
> joerg
> }

I think you need to mix @Tbl with @Diag; also you can add ylabels to
arrows, no need for extra lines. The lout below keeps the boxes
vertically centred and keeps everything lined up nicely.

@SysInclude{tbl}
@SysInclude{diag}
@SysInclude{eq}
@SysInclude{doc}
@Doc
@Text @Begin

@CD
@Diag
{
    @Tbl
        marginhorizontal{1.5f}
        address@hidden A| @Cell B| @Cell C|}
    {
        @Rowa
        A{A:: @Box address@hidden sub 1}}}
        B{B:: @Box address@hidden sub 2}}}
        C{C:: @Box vsize{2.5f}
            address@hidden sub 3 = k sub 3 cdot int from 0 to t c sub 2}}}
    }
//
@Arrow address@hidden 1.25f}} address@hidden 1.25f}} address@hidden sub 1}}
@Arrow address@hidden 1.25f}} address@hidden 1.25f}}
    ylabelprox{below} address@hidden sub 2}}
@Arrow address@hidden 1.25f}} address@hidden 1.25f}}
@Arrow address@hidden 1.25f}} address@hidden 1.25f}}
}

@End @Text



-- 
Mark Summerfield, Qtrac Ltd, www.qtrac.eu
    C++, Python, Qt, PyQt - training and consultancy
        "Rapid GUI Programming with Python and Qt" - ISBN 0132354187