Add interface on GrDrawTarget to reserve vtx/idx space at same time

[bsalomon, 2012-03-12 14:23:09]

GrDrawTarget allows a caller to reserve space for vertices and indices for
drawing. How that data lives is allocated is up to the GrDrawTarget subclass. A
subsequent CL will allow the GrInOrderDrawBuffer to auto-flush itself based on
vtx/idx requests. However, it can do a better job of making that decision if it
sees both requests at once. This change just adds that API to GrDrawTarget and
makes the often-used AutoReleaseGeometry stack helper call it. The method is
virtual so that the buffered subclass will be able to insert a decision about
flushing.

[TomH, 2012-03-12 14:31:37]

LGTM modulo 1 comment nit.

Given that passing in 0/NULL is legal, would it be reasonable to hide the two
individual functions, and make clients only use the joined function?

http://codereview.appspot.com/5796066/diff/4003/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

http://codereview.appspot.com/5796066/diff/4003/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:354: * 0 vertexCount will leave the vertex source
unmodified. The same goes for
What is the "vertex source"?
Passing 0 will change *vertices...

[bsalomon, 2012-03-12 17:50:40]

Updated to incorporate your good suggestion that only the combined function be
exposed. One callsite in GrTextContext had to be modified. I also tried to
improve the comments about vertex / index sources.

[TomH, 2012-03-12 19:34:37]

LGTM. We really don't have any other clients? Will this be able to roll?

[bsalomon, 2012-03-12 19:54:00]

On 2012/03/12 19:34:37, TomH wrote:
> LGTM. We really don't have any other clients? Will this be able to roll?

GrDrawTarget isn't a publicly visible class. The other clients all use
AutoReleaseGeometry which now calls the new function.

[bsalomon, 2012-03-13 12:41:18]

Closed with r3371