Re: [Alephmodular-devel] Brainstorming on bitmaps

[Mark L. <hav...@ma...>]

> Typical usage would be:
> 	Request current buffer from display system
> 		(it is limited as in dimensions, display system knows this)
> 	Lock down the buffer
> 	Get a bitmap from the buffer
> 	Render operations on the bitmap
> 	Release the bitmap
> 	Perform drawing operations on the buffer (access to platform native 
> elements available?)
> 	Unlock the buffer
> 	Ask display system to swap buffers

Add "Obtain the dimensions of the buffer" (oh, you got to that later).

What do you think about the ability to move the origin of a context? 
Aleph One does the main screen layout with this; it makes the game view 
size and screen size essentially independent, but I personally find it 
very confusing to do layout in this fashion. Perhaps it would be better 
to do some complex calculations and rebuilding of buffers when the 
screen is resized instead of a large number of simple (but annoying) 
calculations every frame.

> Locking pixels.

Are you talking about the original MacOS LockPixels() concept (which 
IIRC was meant to protect pixmaps from memory manager housekeeping) or 
some sort of mutex for multithreaded drawing? The former is probably 
obsolete on everything except OS9.

> Ponder... Setting the drawing context should occur seperately

Maybe this should be changed to a stack-based mechanism (like Quartz) 
instead of requiring the program itself to cache and restore the 
previous state.

> 	world_pixels is used as the offscreen buffer for saved game preview 
> pictures :/

With proper abstraction it should be trivial to temporarily point the 
renderer at an offscreen buffer instead.

Rectangle representation: Do we use OS9-style absolute boundaries 
(left/top/right/bottom) or "relative" rectangles (x/y/width/height)? Is 
the origin at the physical top or bottom of a buffer? (Carbon and 
OpenGL disagree on this last bit, which has caused me its share of 
confusion too. How do Windows and SDL work?)

--Mark

"Notice the fine lines, the attention to detail, the overall 
craftsmanship... You just don't see that in giant evil robot planes any 
more."

Random acts of programming: http://homepage.mac.com/haveblue