Lua and 3.2

[Jim Bauwens]

So, the new TI-Nspire OS 3.2 is out. What does that mean for Lua developers ?
Well, a lot ! There are some important changes that you all should know about, in order to make your applications works perfectly on 3.2.
TI has done a great job keeping compatibility, but there are some tiny stuff that might cause certain programs not to run (properly).


Compatibility mode
Let me first begin with the compatibility mode. TI has 2 "apiLevel's" in 3.2. apiLevel 1.0 provides backwards compatibility for <3.2 OS's by keeping the old API structure.
All documents created for 3.1 and previous will run in that apiLevel by default. This is because some changes in the XML structure of the document. So most programs and games should run fine by default.
Then there is apiLevel 2.0. This apiLevel has some big changes to the API structure, so you will have to update some of your code in order to have some of they new 3.2 stuff. However, it is currently not possible to create apiLevel 2.0 documents with Luna due to changes in the XML structure. I have given the details of the changes to ExtendeD so he will probably update Luna soon.

For the best support and guarantee that you are using the correct apiLevel, you should add the following to the top of new Lua documents you create:

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platform.apilevel = '1.0' or platform.apilevel = '2.0'

Please note that using apiLevel 2.0 with the current Luna will result in an error. (I have a little customized version myself, but I'm not going to release it because it's Linux only, and I'm sure ExtendeD will update Luna soon.)


Events
*on.create is removed in apiLevel 2.0 and replaced with on.construction. This event handler is guaranteed to run before all others.
* on.getFocus is called when the script receives user input focus.
* on.loseFocus is called when the script loses user input focus.
* on.getSymbolList is called when the script app symbol list is being serialized to the clipboard.

Graphical operations
* Most graphical operations are now anti-aliased. This makes that applications look more pretty
* gc:setColorRGB now supports one number as input (as well as the old style). For example, you can do gc:setColorRGB(0xFF00CC) or gc:setColorRGB(0)
* You can not use coordinates for drawing to the screen above/under (-) 32 000. Normally this shouldn't affect anyone, but because of this Cubefield refuses to run.

* In apiLevel 2.0 platform.gc() is removed and replaced with platform.withGC(). An example of it:

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function getStringWidth(str, gc)   return gc:getStringWidth(str) end function on.construction()   local strw = platform.withGC(getStringWidth, "The game") end

So what it does it call the function you give as first argument and pass a dummy GC to it as last argument.

D2Editor
D2Editor is greatly improved, and it finally useful


require
There are three modules that you can 'require': physics, color, and strict.
The physics module is the chipmunk physics engine.
color is just a table containing colors. color.red (or color["red"]) will return the color code for red.
I have no idea what strict is or does

Usage: require 'modulename'


Physics
Maybe the best part of it of. OS 3.2 now includes the Open Source Chipmunk physics engine, and you can use it right from Lua!
This will allow some great games and applications
However it's is far to complex to detail in this post, so I will probably write a tutorial about it soon


Image
Normally 3.2 would have many updates to the image, but sadly enough they did not make 3.2 and are pushed for the next OS.
However, there is one function that made it, and that is image.rotate. This allows you to rotate images in anyway.
But beware, it is not the fastest function out there.

Math
math.eval has got some friends: math.evalStr, math.getEvalSettings and  math.setEvalSettings.

Platform
I already mentioned platform.withGC, but there are still two other newcomers:
* platform.registerErrorHandler, this allows you to take actions when an error occurs in your document. Pretty nice
* platform.window:setFocus, regain focus in your script.
* platform.hw(), returns a number corresponding to the device the scripts is running on.

Variable
* var.recallAt, fetch data from a certain spot in a list or matrix
* var.makeNumericList, create a list in the symbol table. The create list will work much more efficient with other var functions.

Toolpalette
In apiLevel 2.0 the names of toolpalette items may be changed dynamically while the program is running. Calling toolpalette.register(nil) deactivates the toolpalette.

Well, that's about it. I'm sure there are some stuff I forgot, but you can find them all in the API documentation here http://education.ti.com/downloads/guidebooks/ti-nspire/3.2/TI-Nspire_Scripting_API_Reference_Guide/TI-Nspire_Scripting_API_Reference_Guide_EN.pdf .
Good luck and may the coding force be with you!

Links:
Wiki version of this post with more details

[Nick]

Wow, thanks for that jim

now i have some questions for you:
    1) can you declare classes in on.construnction, or do you still have to put before this? because with on.create, you had to place them before the on.create
    2) is it plaform.apilevel = '1.0' at the top, or really both of them with an 'or' in between?
    3) how are error's formatted when you use the errorhandler? i mean, how can one use them?
    4) is gc:setAlpha() working?

that's about it

now i'm waiting for the tutorial xp

[Jim Bauwens]

1) Do you mean objects ? (obj1 = TheGame() )
Normally yes, as this will run before all other events and they will be declared when other evens run.
2) It's on of the two, no or in between
3) I haven't tried to use this function yet. As soon as the new documentation is out I'll link it here so you can have a peek in it
4) TI removed it several build versions ago, where we warned several people that it would go away. It might return in the future, but I can not guarantee that..
It's also worth noting that TI never mentioned this function, as it still had some bugs.

The tutorial should not take too long ..

[adriweb]

Here's the Wiki version of it, with more details and links etc.:

http://wiki.inspired-lua.org/Changes_in_OS_3.2

Can you put that too on the post, jim ?

[Jim Bauwens]

Added a link to the API doc

[Levak]

Important notice : on.construction() hasn't the same goal as on.create().

Indeed, on.construction() is executed just after the de-serialization of the XML contrary to on.create where platform, math, table etc .. lib were loaded.
I made all my best in order to have on.create back in 3.2 but TI didn't wanted to listen to the problems I showed.
I explained that on.construction has no more interest but didn't replied ...

[adriweb]

Hmm, I thought there would be some loaded libs already when on.construction gets fired, but if it's not the case, then I don't really see the point of having that event since init stuff can be put outside of any functions at the end of the programs for example and it would behave the same way ... ?

[Art_of_camelot]

Nice list Jim. I'm not much of an Nspire guy, but I can appreciate your dedication. =)

[Jim Bauwens]

Levak, the platform, math, etc libs do get loaded before on.construction runs. However, the display window isn't initialized yet, so platform.window:height() and platform.window:height() return 0.
It would be a good idea to put this code in on.resize.
on.construction is still good for var, document, math, local and other stuff.

Art_of_camelot: Thank you
Also, maybe this topic could be pinned ? I think it's pretty useful for people

Edit: yay, it is pinned !