A diamond acts much like a box except that its corners are rotated around the center point such that they become the shape’s four primary cardinal points:
D: diamond "Cardinal" "Points" dot ".n" above at D.n dot " .e" ljust at D.e dot ".s" below at D.s dot ".w " rjust at D.w→ /pikchrshow
Indeed, before Pikchr acquired this primitive, the workaround was to draw an invisible box to hold the text, then draw lines between its cardinal points:
box width 150% invis "“Diamond”" "Label" line from last.w to last.n to last.e to last.s close→ /pikchrshow
This does work, and it has the advantage of being compatible with the
original PIC and with GNU dpic, but it also has a number of
weaknesses, one of which is evident in comparing the examples above: the
labels aren’t as well-centered when manually drawing the diamond.
Another is the need for that 150% fudge factor to the invisible box’s width, without which the labels would be truncated by the dimensions Pikchr calculates for the invisible bounding box:
box invis "“Diamond”" "Label" line from last.w to last.n to last.e to last.s close→ /pikchrshow
A third advantage falls out of this fact: the “fit” attribute works as
expected for Pikchr diamonds. It cannot with the manual PIC-compatible
workaround due to the lack of a properly-calculated bounding box, one taking
into account the rotated cardinal points:
text "Unfitted:" diamond "D" text "Properly fitted:" diamond "D" fit text "Badly fitted:" box invis "D" fit line from last.w to last.n to last.e to last.s close→ /pikchrshow
There’s a fourth, more subtle advantage to having this primitive built into the language: the location of the ordinal points is now well-defined:
D: diamond "Ordinal" "Points" dot " .ne" ljust above at D.ne dot " .se" ljust below at D.se dot ".sw " rjust below at D.sw dot ".nw " rjust above at D.nw→ /pikchrshow
To replicate that with the PIC-compatible hack above, you’d have to do the geometry to work out where those points land along the lines. It’s better to leave that bit of tedious math to the Pikchr renderer.
Unlike a box, you cannot currently round the corners on a diamond. You
can, however, programmatically override the default height and width
by redefining the diamondht and diamondwid variables. Here we show
two different ways of making the diamond 25% larger:
D: diamond thick "Diamond" "Dimensions" width 125% height 125%
X1: line thin color gray left 70% from 4mm left of (D.w,D.n)
X2: line same from 4mm left of (D.w,D.s)
text "height" small at 1/2 way between X1 and X2
line thin color gray from previous text.n up until even with X1 ->
line thin color gray from previous text.s down until even with X2 ->
X3: line thin color gray down 50% from 2mm below (D.w,D.s)
X4: line same from 2mm below (D.e,D.s)
text "width" small at 1/2 way between X3 and X4
line thin color gray from previous text.w left until even with X3 ->
line thin color gray from previous text.e right until even with X4 ->
diamondht *= 1.25
diamondwid *= 1.25
diamond thick "Diamond" "Dimensions" at 1.5in right of D
→ /pikchrshow