use sub pixels accuracy when drawing shapes

[assefa]

when transorming shapes from geographical to image coordinates, it could be possible to use double values instead of inegers. There need to be a custon msTransformShapeAGG function. We could also test performance and see if the function can be optimized without affecting quality of rendering.

[assefa]

First try using double values is added in r6116

[sdlime]

Replying to assefa:

First try using double values is added in r6116

I'm wondering if this needs to be AGG specific at all. We're already casting the rounded doubles to ints in mapgd.c... Have you guys looked at GD output without rounding?

Steve

[assefa]

I have not tried it with a gd output. The function in AGG is slower than using the regular msTransformShapeToPixel function. There might be way to optimize it without affecting quality but at this point I did not want to "disturb" the gd output. I will do more tests in the coming weeks and if it is reasonable both agg and gd can use the same function.

[sdlime]

Assefa, did you ever do follow up testing on this one?

Steve

[assefa]

Steve, I did not follow on this fr a while. All efforts I did at the time went into the agg output. Is this still an issue we should look into?