Inspired-Lua Wiki - User contributions [en]

TI.Image

2013-09-17T19:38:02Z

Jimbauwens:

The TI.image format is used by TI-Nspire Lua to display images. It uses a bitmap based format with no compression at all. The image data consists out of a header section and a data section.

==The header==
The header consists out of 20 bytes of data arranged as presented in the following table. All fields are little endian integers.

{| class="wikitable"
|-
! Offset !! Width (bytes) !! Contents
|-
| 0 || 4 || Pixel width of image
|-
| 4 || 4 || Pixel height of image
|-
| 8 || 1 || Image alignment (0)
|-
| 9 || 1 || Flags (0)
|-
| 10 || 2 || Padding (0)
|-
| 12 || 4 || The number of bytes between successive raster lines (generally 2*width)
|-
| 16 || 2 || The number of bits per pixel (16)
|-
| 18 || 2 || Planes per bit (1)
|}

==Image data==

The image data immediately follows the header. Pixels are arranged in rows. Each pixel is a little endian 16-bit integer with five bits for each color red, green and blue. The top bit determines if the pixel is drawn. If its zero (0), the pixel is not drawn (alpha). If it is one (1), the pixel is drawn in the RGB color of the remaining 15 bits.

Example, converting a RGB color:

R=255 → R = 31 (because each pixel can only have 5 bits per color) 
G=012 → G = 1 
B=123 → B = 15 
A= 1 (alpha flag, make that the pixel is visible)

To make things easy, we will fist convert it to binary in this form:
A RRRRR GGGGG BBBBB
With the above data:
1 11111 00001 01111

But, since the data needs to be stored in little endian, it has to be in this form:
GGGBBBBB ARRRRRGG
Quite easy to fix, as we only need to swap both halves:
00101111 11111100

Ok, now we have our pixel data!
This data can then be put inside a string using escape characters (8 bit per escape character), for example:
00101111 becomes “\047” and 11111100 becomes “\252”. If a escape character is ASCII UTF-8 representable, you can replace it with the equivalent char (“\122” can be replaced by “z”).

Example implementation in a program:

<source>
str = "\007\000\000\000\008\000\000\000\000\000\000\000\014\000\000\000\016\000\001\000alalalalalalalal\000\244\000\244al\000\244\000\244al\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244\000\244al\000\244\000\244\000\244\000\244\000\244alalal\000\244\000\244\000\244alalalalal\000\244alalalalalalalalalal5"

img = image.new(str)

function on.paint(gc)
gc:drawImage(img,10,10)
end
</source>

==External Links==

[[User:Adriweb|Adriweb]] made [http://www.youtube.com/watch?v=YQhrMHNkL3A a video] showing some direct manipulations of the TI-Image, in order to understand better the format in general.

[[User:jimbauwens|Jim Bauwens]] made [http://bwns.be/jim/tiviewer.html a image previewer], [http://bwns.be/jim/sprite.html a sprite creator] and a basic [http://bwns.be/jim/convert.py python image converter] (you need PythonMagick to run this)

These tools are not official and we'll update this as soon as we can / are allowed to.

In the official Nspire Lua toolkit, TI included in their software a feature that converts an image (with a common format such as jpg, png etc.) into a TI.Image format.

==References==
http://en.wikipedia.org/wiki/Highcolor

2011-09-10T18:17:15Z

Jimbauwens: Author: Everaldo Coelho License: LGPL

Author: Everaldo Coelho
License: LGPL

File:Rtf icon.png

2011-09-10T18:14:56Z

Jimbauwens: Rich Text Format

Rich Text Format

2011-06-01T12:27:41Z

Jimbauwens: Created page with "var.'''store''' is a function that is part of the Var Library. The function set the content of a variable in the current document. Returns nil when the operation su..."

var.'''store''' is a function that is part of the Var Library.

 

The function set the content of a variable in the current document. Returns nil when the operation succeeded, otherwise an error message. 

== Syntax ==

var.'''store(varname, data)''' stores data in the variable varname (must be a string).

== Example ==

<source lang="lua">
function on.create()
var.store("sol","very very very many")
end

function on.paint(gc)
variable = var.recall("sol") --assuming that sol exists
gc:drawString("The diameter of the sun is " .. tostring(variable) .. " KM", 10, 10, "top")
end
</source>

This code retrieves the content of the variable sol (string), and prints it on the screen.

== See also ==

*[[var.list]] 
*[[var.recallstr]] 
*[[var.recall]] 
*[[var.monitor]] 
*[[var.unmonitor]] 

[[Category:var]]

var.recallstr

2011-06-01T12:23:00Z

Jimbauwens: Created page with "var.'''recallstr''' is a function that is part of the Var Library. The function returns a the content of a math variable in the current document as a string. If it ..."

var.'''recallstr''' is a function that is part of the Var Library.

 

The function returns a the content of a math variable in the current document as a string. If it cannot be converted to a string, it returns nil and an error message. 

== Syntax ==

var.'''recallstr(varname)''' returns the content of the variable varname (must be a string).

== Example ==

<source lang="lua">
function on.paint(gc)
variable = var.recall("sol") --assuming that sol exists
gc:drawString("The diameter of the sun is " .. variable .. " KM", 10, 10, "top")

--the difference with the other script in the recall page is that you don't need to use tostring for numbers
end
</source>

This code retrieves the content of the variable sol (number), and prints it on the screen.

== See also ==

*[[var.list]] 
*[[var.recall]] 
*[[var.store]] 
*[[var.monitor]] 
*[[var.unmonitor]] 

[[Category:var]]