lua9 Documentation

lua9 is a custom lua interpreter including bindings to various plan9 libraries. This document is not meant to replace the plan9 documentation, please refer to the man pages in section 2 for the documentation of individual functions.

Notes

The API is mostly a one-for-one translation of the C API with some slight changes to make the API feel more "lua-ish". The most significant differences are:

• The API is split across several modules (draw, event, etc.).
• Naming respects lua conventions instead of their original C name.
• Functions that take pointers as out parameters (e.g. event) instead return the value and may return multiple values (e.g. icossin).
• In lua, indices start at one not zero. The API respects the lua convention for function returning indices (e.g. emenuhit)
• Value types (e.g. Point, Rectangle) are mapped as lua tables, reference types (e.g. Image, Font) as userdata.

API Reference

Module draw

draw.init(title)

This is the C initdraw function.
The important difference is that it does not handle the additional parameters allowed by initdraw. When called, init will check for the existence of an eresized function as with the C API.
Upon success, three global variables are defined: display, screen and font.

draw.draw(dst, r, src, mask, p)

draw.replxy(min, max, x)

draw.repl(r, p)

draw.replclipr(i, r, clipr)

draw.line(dst, p0, p1, end0, end1, thick, src, sp)

draw.poly(dst, pts, end0, end1, radius, src, sp)

draw.fillpoly(dst, pts, wind, src, sp)

draw.bezier(dst, p0, p1, p2, p3, end0, end1, radius, src, sp)

draw.fillbezier(dst, p0, p1, p2, p3, w, src, sp)

draw.bezspline(dst, pts, end0, end1, radius, src, sp)

draw.fillbezspline(dst, pts, w, src, sp)

draw.ellipse(dst, c, a, b, thick, src, sp)

draw.fillellipse(dst, c, a, b, src, sp)

draw.arc(dst, c, a, b, thick, src, sp, alpha, phi)

draw.fillarc(dst, c, a, b, src, sp, alpha, phi)

draw.icossin(deg)

Returns two values: cosp and sinp

draw.icossin2(x, y)

Returns two values: cosp and sinp

draw.border(dst, r, i, color, sp)

draw.string(dst, p, src, sp, f, s)

draw.stringn(dst, p, src, sp, f, s, len)

draw.stringbg(dst, p, src, sp, f, s, bg, bgp)

draw.stringnbg(dst, p, src, sp, f, s, len, bg, bgp)

draw.allocimage(d, r, chan, repl, col)

draw.allocimagemix(d, one, three)

Constants

The following constants are exported:

• END_SQUARE, END_DISC, END_ARROW, END_MASK

Module event

event.init(keys)

Initialize event handling. This is the einit C function.

event.event()

Returns:

• The event key
• The event structure

event.kbd()

event.canmouse()

event.cankbd()

event.timer(key, n)

event.enter(ask, s, m)

The s parameter is used as an initial value in the text field.

event.menuhit(but, m, menu)

The menu is expected to be a table of strings. The generation of menu items is not supported currently.
Returns:

• Selected index (starting at 1) or nil

Constants

The following constants are exported:

• MOUSE, KEYBOARD

Module g

Geometry related functions.

g.pt(x, y)

g.rect(x0, y0, x1, y1)

g.rpt(p, q)

g.addpt(p, q)

g.subpt(p, q)

g.mulpt(p, a)

g.divpt(p, a)

g.rectaddpt(r, p)

g.rectsubpt(r, p)

g.insetrect(r, n)

g.canonrect(r)

g.eqpt(p, q)

g.eqrect(r, s)

g.ptinrect(p, r)

g.rectinrect(r, s)

g.rectxrect(r, s)

g.badrect(r)

g.dx(r)

g.dy(r)

Module key

key.eq(k, str)

Checks whether k is equal to str. This is a convenience function to help with lua not having a character type.

Constants

The following constants are exported:

• HOME, UP, DOWN, PGUP, PRINT, LEFT, RIGHT, PGDOWN, INS, END, SOH, STX, ETX, EOF, ENQ, ACK, BS, NACK, ETB, DEL, ESC.

Module color

Constants

The following constants are exported:

• OPAQUE, TRANSPARENT, BLACK, WHITE, RED, GREEN, BLUE, CYAN, MAGENTA, YELLOW, PALE_YELLOW, DARK_YELLOW, PALE_GREEN, DARK_GREEN, MED_GREEN, DARK_BLUE, PALE_BLUE_GREEN, PALE_BLUE, BLUE_GREEN, GREY_GREEN, PALE_GREY_GREEN, YELLOW_GREEN, MED_BLUE, GREY_BLUE, PALE_GREY_BLUE, PURPLE_BLUE, NOT_A_COLOR, NO_FILL