How to create a new Graphic class to give suport for a new format file
extenxion
lazarus / 39-Graphics

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dcelso · 2013-02-25 06:53

Hello to all, anybody know
How to create a new Graphic class to give suport for a new format file
extension to TPicture?

My custom format file is very similar to (but simpler than) TBitmap, 
with more custom image information.

I tried extend TBitmap class, overrriding the
loadfromfile,loadfromstream,savetofile,savetostream and
getfilextension methods. But this not seems enough. TPicture and
TImage still continues withot can load my custom format image file.

Thanks to all.

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taazz · 2013-02-25 08:39

after you have extended the tbitmap class you need to register your
class with the internal file format mechanism calling the
RegisterFileFormat function. Still this is not enough to see the
results inside your IDE, you need to create a new package with your
extra class and the call to registerfileformat and install it in the
ide by rebuilding it. then you will see the new format in your IDE.

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dcelso · 2013-02-26 12:55

Thanks, Now to use in my projects i need put the call of this
function  on create of my form.

  TPicture.RegisterFileFormat('map','DIV MAPs',TMAPGraphic);    

But, there is another method to do it automatically?, I have
TMAPGraphic in another  .pas file.

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taazz · 2013-02-26 13:26

no not automatically, if you want to make sure it is always called
even if you forget to call it your self, call it from the units
initialization section eg

Unit MapGraphic;
interface
........
implementation
.......

initialization
 TPicture.RegisterFileFormat('map','DIV MAPs',TMAPGraphic);    

end.