Pressure sensitivity

Boudewijn Rempt boud at
Thu Jan 22 14:22:50 CET 2004

On Thursday 22 January 2004 14:13, Patrick Julien wrote:

> This makes considerably more sense to me.

It's something that needs investigation, because it also seems necessary for a 
a proper implementation of an anti-aliased brush. (There's some pretty scary
code in the Gimp to implement this -- but our brush tool isn't nearly pretty 
enough now.

However, there are several concerns with using one big temporary layer that 
worry me a bit:

* Creating the layer might be costly, especially if big.
* Wiping the layer between paint operations or recreating it might be costly.
* How costly is compositing only the dirty rect of the temporary layer? I  
mean, is bitBlting from a section of a layer onto another layer not very 
* Memory consumption... Currently, if I paint a line along the edges of a 
large canvas, only the edge tiles will get dirtied and included in the undo 
list, I guess. But if I use a big overlay layer, and blt the dirty rect to 
the destination layer, all tiles will get dirtied. It might be possible to 
optimize this, but I don't look forward to that: that would be very 

Boudewijn Rempt |

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