[fpc-pascal] questions on fpimage

[Marc Santhoff]

Hi,

firstly a happy new year to you all and keep on rocking!

While reading the fpimage unit code I found some pieces I don't
understand and could not clear up reading the docs. Here we go:

<code>
TFPCustomImage = class(TPersistent)
[...]
    public
[...]
      property  Extra [const key:string] : string read GetExtra write SetExtra;
      property  ExtraValue [index:integer] : string read GetExtraValue write SetExtraValue;
      property  ExtraKey [index:integer] : string read GetExtraKey write SetExtraKey;
      procedure RemoveExtra (const key:string);
      function  ExtraCount : integer;
</code>

Whats that good for? Ist to tag images inside my own program or does it
handle image meta data like EXIF and stuff?


And at the end:

<code>
initialization
  ImageHandlers := TImageHandlersManager.Create;
</code>

Looking at this class it seems to be sort of a type registry, maybe able
to detect type and name or instantiate the reader and writer classes.
How ist that to be used and do I need to care for?


TIA,
Marc