Lua Programming

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Revision as of 21:13, 17 April 2011 by AdRiWeB (talk | contribs) (Platform)
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The TI-Nspire allows, since OS v3.0, programming with the Lua language through a hidden application "TI.ScriptApp".

This page describes how to setup a Lua development environment and documents the currently known Lua functions for the Nspire, and a brief description of how to use the functions.

Note: Neither the io nor os libraries are present for the TI-Nspire, which seems to be running a light version of Lua 5.1.4.

Here's a dump of a lot of functions available in the API : Link to the dump.


Prerequisites

Lua is only supported starting from OS v3.0.1. Creating Lua scripts is currently not officially supported by TI, you need one of the following third-party tools to convert Lua scripts to TI-Nspire documents:

  • LUAtoTNS.sh (bash script, works on Linux, Mac OS and Unix, or Windows + Cygwin or Windows + MSYS).
  • maketns.py (Python script, cross-platform)
  • lua2ti (Windows + .NET Framework v4.0)
  • lua2ti_linux (Linux + Mono v3.5)

You may also want to install Lua on your computer: luac -p can be used to check the syntax of your script before running it on a TI-Nspire or an emulator.


Standard Library

  • _G - Global Variable - A global variable (not a function) that holds the global environment (that is, _G._G = _G). Lua itself does not use this variable; changing its value does not affect any environment, nor vice-versa. (Use setfenv to change environments.) - taken from Lua docs
  • print - print (···) - Receives any number of arguments, and prints their values to stdout, using the tostring function to convert them to strings. print is not intended for formatted output, but only as a quick way to show a value, typically for debugging. For formatted output, use string.format. - taken from Lua Docs
  • tostring - tostring (e) - Receives an argument of any type and converts it to a string in a reasonable format. For complete control of how numbers are converted, use string.format. If the metatable of e has a "__tostring" field, then tostring calls the corresponding value with e as argument, and uses the result of the call as its result. - taken from Lua Docs.
  • xpcall - xpcall (f, err) - xpcall calls function f in protected mode, using err as the error handler. Any error inside f is not propagated; instead, xpcall catches the error, calls the err function with the original error object, and returns a status code. Its first result is the status code (a Boolean), which is true if the call succeeds without errors. In this case, xpcall also returns all results from the call, after this first result. In case of any error, xpcall returns false plus the result from err. - taken from Lua Docs
  • select - select (index, ···)- If index is a number, returns all arguments after argument number index. Otherwise, index must be the string "#", and select returns the total number of extra arguments it received. - Taken from Lua Docs
  • getmetatable -
  • upack -


GC (as in Graphics Context)

Note: You need to add “gc:” before each of these commands in order to use them. ex. gc:setAlpha().

The amount of the screen available to Lua programs is 318 by 212 pixels.

  • begin -
  • clipRect -
  • drawArc(x, y, width, height, start angle, finish angle) Note, to draw a circle, use drawArc(x - diameter/2, y - diameter/2, diameter,diameter,0,360) where x and y are the coordinates of the middle.
  • drawImage ? First argument in format “TI.Image”
  • drawLine(xstart, ystart, xend, yend) Draws a line starting at the point (xstart,ystart) and ending at the point (xend, yend)
  • drawPolyLine(int list1 [,int list2, .., int listN]) Draw a shape from a list contaning successively the x and y coordinates of each point the line have to draw. ex : drawPolyLine(0,0, 0,100, 100,100, 100,0, 0,0) = drawRect(0,0,100,100). If there are multiple argument (which can be 4 elements list to represent lines), each list has to contain an even number of element.
  • drawRect(x, y, xwidth, yheight) Draws a rectangle at (x,y) with the “x” side being “xwidth” long and the “y” side being “yheight” long
  • drawString(string, x, y, PositionString) PositionString is the string’s anchor point and can be “bottom”, “middle”, or “top”.
  • fillArc(x, y, width, height, start angle, finish angle) see drawArc
  • fillPolygon(int list1 [,int list2, .., int listN]) see drawPolyLine
  • fillRect(x, y, width, height) see drawRect
  • finish -
  • getStringHeight(string)
  • getStringWidth(string)
  • isColorDisplay Bool (Read-only) Returns 1 if color, 0 if not.
  • setAlpha ≈ transparency ?
  • setColorRGB(red, green, blue) Values range from 0 to 255.
  • setFont(font, type, size)
  • font {“sansserif”, ..}, type {“b”, “r”, “i”}, size(int)
  • setPen(size, smooth)
  • size {“thin”, “medium”, "thick"}, smooth {“smooth”, ..}

Platform

These are mainly read-only. These work by writing "platform." in front of them. Example : "platform.window:invalidate()"

  • apilevel() : Returns 1.0.0
  • window
*width() - Returns the width of the window
*height() - Returns the height of the window
*invalidate() - Repaints the window
  • isDeviceModeRendering() Returns true or false whether the unit is "rendering" or not
  • gc ?
  • isColorDisplay() Returns true if the unit the code is being run on has a color display (-> Nspire CX), and false otherwise.

Events

  • on.charIn(string) is called when the Nspire detects a non arrow key being pressed. ch is the character it detect. If you want to auto start an event in the file linked to key r(like a reset) put on.charIn(“r”) where you want. This Lua program lets you display the value of a valid non arrow key :
c = “”
function on.charIn(ch)
	c = ch
end
function on.paint(gc)
	gc:setFont(“sansserif”, “r”, 10)
	gc:drawString(c, 0, 0, “top”)
end
  • on.paint(gc) is called when the GUI is painted. 'gc' is the Graphics Context (see above)
  • on.arrowKey(key) is called when an arrow key from the clickPad/TouchPad is pressed
  • on.enterKey() is called when the enter key is pressed.
  • on.escapeKey() is called when the escape key is pressed.
  • on.tabKey()is called when the tab key is pressed.
  • on.mouseDown(x, y) is called when we press a button of the mouse. X and Y are the pressed point coordinates.
  • on.help() is called when the combo-key Ctrl H is pressed.
  • on.timer()
  • on.resize()