rotated & colour literals

Two small conveniences for figures: rotated labels and native colour literals.

rotated <degrees>

A per-string text attribute (binding like ljust — to the string it follows). Angles are counter-clockwise, pic’s convention; the rotation pivots on the text’s anchor point.

.PS
margin = 0.12
A: arrow right 2.4 "gradient ascent" rotated 18 above
"y axis" rotated 90 at A.start + (-0.3, 0.55)
arrow from A.start up 1.1 dashed
.PE

• Composes with the font attributes: "note" bold rotated 45.
• fit and standalone-text bounds cover the rotated extent, so a rotated caption gets a properly sized box.
• Like classic pic, labels attached to lines/boxes may overflow the canvas edge — give the drawing breathing room with margin.
• Math lines ($…$ under texlabels) ignore it.

aligned — follow the line

aligned (pikchr’s spelling) rotates a label to the host segment’s angle automatically, so edge labels ride their line. It works on linear objects (line/arrow/spline) and normalizes the angle to keep the text upright — a leftward or downward segment reads horizontally, never upside down.

.PS
margin = 0.12
arrow from (0,0) to (2.4,1.3) "gradient ascent" aligned above
arrow from (0,0) to (2.4,-1.1) "descent" aligned below
.PE

Colour literals: rgb(r,g,b) and 0xRRGGBB

The colour grammar (for outlined, shaded, color, hatchcolor and gradient) accepts two native literal forms besides names and strings:

.PS
box shaded rgb(27,94,32) "rgb()" bold wid 1
circle outlined 0xb3261e rad 0.35 at last box.e + (0.9,0) "hex" italic
.PE

• rgb(r,g,b) takes full expressions (rgb(v, v/2, 0)), components 0–255; out-of-range values are an error.
• 0xRRGGBB follows Pikchr’s numeric colours; 0x… is a general hexadecimal number literal, usable anywhere a number is.
• Why not bare #1b5e20? In pic, # starts a comment — the quoted form shaded "#1b5e20" has always worked and still does.

A colour can also be held in a variable or computed, so a palette defined once drives a whole figure (handy for the for-loops that plot the easing curves):

.PS
accent = 0x2f855a
box outlined accent "variable" wid 1
circle shaded (accent + 0x60) rad 0.35 at last box.e + (0.9,0) "expr" italic
.PE

• A bareword that names a variable resolves to its value as a 0xRRGGBB colour (accent = 0x2f855a; … outlined accent); a bareword that is not a variable stays a literal colour name (outlined crimson), so existing sources are unaffected.
• Wrap an expression in parentheses for arithmetic in colour position (shaded (accent + 0x60)), just like rgb() takes expressions.
• A quoted "0xRRGGBB" string is normalised to #rrggbb (the bare literal already worked; the string form no longer slips through as invalid colour).

Any unknown colour name — a typo ("crimsom"), a malformed hex ("#12g456") — is flagged with an invalid_color warning in the --json bundle (with a “did you mean” suggestion), instead of silently rendering blank. The colour is still passed through unchanged, so the warning is advisory and never blocks rendering. Valid forms — the CSS named colours, #hex, rgb()/hsl(), and the dvips/xcolor names the dpic corpus uses (Dandelion, Goldenrod, …) — stay quiet.