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List:       kde-kimageshop
Subject:    Re: SelectionTool
From:       Andrew Richards <physajr () phys ! canterbury ! ac ! nz>
Date:       1999-08-18 21:28:21
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> Am Mit, 18 Aug 1999 schrieb Sven Fischer:
> > Hi all,
> > 
> > as my first attempt on writing code for KImageShop I wanted to try to
> > write a Selection Tool, at first rectangle selection. Since I don't
> > want to dig through the whole code by myself, I think you can help me
> > a bit:
> > 
> > To show the selected region one has to draw the rectangle above the
> > pictures...I would think of a special always-on-top-layer which is not
> > shown in the layers dialog. Or is there another way already planned
> > for such "drawing"?
> 
> I think a LAYER is too much overhead. The canvasview-widget should draw it
> directly.
> 
> Matthias, Andrew : What do you think ?
>   

Selections are going to have to be very tricky (probably one of the hardest 
things to implement well). I believe a greyscale layer may be the way to go. 
Remember that the selection must be able to be feathered (ie it must be 
able to have an alpha channel). Also remember that some selection mechanisms 
produce very big selections (select by colour for example) and these would 
probably be better described by a layer than by a set of vectors. The dynamic 
tile allocation of layers should keep small selections small, however, 
We could implement a simple selection mechanism now but that would probably
have to be replaced later.

I personally believe that we should wait until the canvas code has stabilized 
an drawing/layers/brushes have been made to work well.

Cheers,

Andrew
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