On 4/29/17 9:56 PM, Sannyasin Brahmanathaswami via use-livecode wrote:
My question is: where is the documentation for AcceleratedRendering
-- exactly what does it do? (don't worry, if the explanation is very
technical.. .let me see it!)
-- when does it help
-- what contexts may there be where it could actually impede performance?
I have been wanting to know that for years. I have the general idea but
I want to know exactly what each command or property does. How does
layerMode interact with rendering and when should I set it? (I used it
incorrectly and submitted a spurious bug report, but I'm still not clear
on why I was wrong.)
Here is what (I think) I do know:
AcceleratedRendering creates an offscreen buffer for objects that have a
non-static layerMode. It then only needs to redraw the particular object
instead of the whole card when you move that object, which is much
faster. If it is a scrolling object (group or field) then the layermode
should be set to "scrolling". If you are going to drag things around or
use the "move" command, then those objects should be set to "dynamic".
If the object doesn't move, or only moves very rarely, its layermode
should stay at the default "static" and no buffer is created.
The compositorTileSize, compositorType, and compositorCacheLimit all
affect the size and behavior of the buffer(s). The defaults provided
have always worked for me so I don't change them. I'm not sure how I
would add up the memory requirements for a set of moving objects so I
stick with the defaults.
I'm guessing it would impede performance if it is creating buffers for
objects that aren't really going to move. You'd have the overhead of the
buffer creation and some decrease in available memory. And from my
incorrect bug report, I gather you shouldn't change layermode on the fly.
What I would like to know is:
- What does layerMode tell the engine, and when is it read? I think it
tells the engine to create a buffer for the object. I had read a long
time ago that it would help to reset the layermode to static if the
object was done moving, but there should have been a caveat: don't reset
if the object will move again later, because in that case you want to
preserve the existing buffer. That seems to imply that resetting
layermode to static will dump the buffer. Is that right?
- When set to true, what does acceleratedRendering actually do? Is it
effectively a command to scan every object on the card and create
buffers? Does it scan more than just the current card?
- Is it okay to turn it on and off as needed? Are there disadvantages to
that, assuming the objects won't be moving any more? Can I turn it on at
the beginning of a handler and turn it off at the end if those objects
won't be moving any more?
- When I turn it off, does it dump all the buffers? I think it does.
- What does it do between card changes? Does it keep old buffers until
the cache limit is hit?
Jacqueline Landman Gay | jac...@hyperactivesw.com
HyperActive Software | http://www.hyperactivesw.com
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