Re: New drawing/scrolling model

[sandmann cs au dk (Søren Sandmann)]

Alexander Larsson <alexl redhat com> writes:

> * Try a tile-based approach for GtkPixelCache to avoid having
>   to do a same-surface copy (usign an intermediate surface) when
>   scrolling the cache.

An alternative to tiles is to keep track of an origin within the
surface:

        +--------+--------------------------+
        | Bot R  | Bottom left              |
        |        |                          |
        +--------O--------------------------+
        | Top R  | Top left                 |
        |        |                          |
        |        |                          |
        |        |                          |
        |        |                          |
        |        |                          |
        |        |                          |
        |        |                          |
        +--------+--------------------------+

with the contents of the surface addressed modulo width and
height. Scrolling is then just a matter of moving that origin, but
copying from the surface may require four separate blits. Similarly,
rendering to some rectangle may have to be split into four separate
operations.


Søren