[fpc-pascal] questions on fpimage

Mattias Gaertner nc-gaertnma at netcologne.de
Thu Jan 5 11:15:49 CET 2017

On Tue, 03 Jan 2017 02:54:05 +0100
Marc Santhoff <M.Santhoff at web.de> wrote:

> 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?

Yes. Both.

> 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?

All image formats register themselves there.
It is used by

You can query it yourself or use the above.


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