Images — multiple — how to display a specific part?

[T U]

I want to use OnScreenDisplay to make use of some files containing many transparent (or not) images.

Some contain many toolbar icons in one row or have several rows and columns. Some folders contain files with the same name but different extensions (e.g. a .jpg and a transparent .png with similar images, which can be their shadow(?) or the form they take when you hover the curson above them or when you click on them etc)

Some of them have some text information in the same folder, like an .xml file.
e.g. for a set of characters in one image:

<?xml version="1.0" encoding="utf-8"?>
<Font family="a_Concepto" style="Bold" size="17" height="25">
<Char code=" " width="10" rect="0 0 0 0" offset="0 0" />
<Char code="!" width="8" rect="0 1 9 29" offset="-1 -2" />
<Char code="&quot;" width="8" rect="10 1 11 29" offset="-2 -2" />
<Char code="#" width="17" rect="22 1 21 29" offset="-2 -2" />

....

<Char code="0" width="17" rect="223 1 19 29" offset="-1 -2" />
<Char code="1" width="17" rect="243 1 16 29" offset="0 -2" />
<Char code="2" width="17" rect="260 1 19 29" offset="-1 -2" />
<Char code="3" width="17" rect="280 1 19 29" offset="-1 -2" />

....


<Char code=";" width="9" rect="431 1 9 29" offset="0 -2" />
<Char code="&lt;" width="18" rect="441 1 17 29" offset="1 -2" />
<Char code="=" width="18" rect="459 1 17 29" offset="0 -2" />
<Char code="&gt;" width="18" rect="477 1 17 29" offset="1 -2" />
<Char code="?" width="15" rect="0 31 17 29" offset="-1 -2" />
<Char code="@" width="22" rect="18 31 23 29" offset="-1 -2" />
<Char code="A" width="18" rect="42 31 20 29" offset="-1 -2" />
<Char code="B" width="18" rect="63 31 20 29" offset="-1 -2" />
<Char code="C" width="16" rect="84 31 19 29" offset="-1 -2" />

....

<Char code="™" width="19" rect="344 181 20 29" offset="-1 -2" />
<Char code="∙" width="9" rect="365 181 9 29" offset="0 -2" />
</Font>


I can display the whole set as one transparent image but how can I make use of the above information? I don't ask how to extract the data the .xml file contains' just where to put it in the OnScreenDisplay line.

In general, how can we choose which one to display and how can we use one of the tile images as a background pattern?
(If not "OnScreenDisplay", some other function which would allow us to display them inside a window, especially if this method is more suitable?)


Note: my screen has a 1024 x 576 resolution (but if you think it's necessary for testing I could temporarily change the settings so it could "display" in other resolutions such as 1024 x 768 or 1280 x 1024 — I don't remember if I have used other resolution numbers).