Add CPU backing store for GrAtlas to reduce texture uploads

Add CPU backing store for GrAtlas to reduce texture uploads.

This change creates a temporary copy of each GrPlot on the CPU
side. As we add glyphs to a plot, a dirty rectangle is tracked,
and just before we render text we upload all of the dirty areas
to the atlas texture. Once a plot is nearly full, we assume that
we may only be adding one or two glyphs before rendering, so we
delete the CPU backing memory to save space, and upload directly.

BUG=366225
Committed: http://code.google.com/p/skia/source/detail?r=14729

[jvanverth1, 2014-05-12 19:06:04]

This is not quite done. We'd need to add a
fContext->getFontCache()->updateTextures() or equivalent call for the layer
changes, but I'm not sure where the best place would be. Alternatively, I could
add a flag to GrAtlasMgr that would only enable this for fonts.

[robertphillips, 2014-05-12 19:45:51]

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp
File src/gpu/GrAtlas.cpp (right):

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:59: // create backing memory on first use
// Once the plot is nearly full we will revert to uploading each subimage
individually

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:68: if (NULL != fPlotData) {
const unsigned char* ?

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:107: int rowBytes = fBytesPerPixel*fRects->width();
const unsigned char* ?

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:119: // at a time, so free up the memory and upload any new
images directly.
static const int kNearlyFullTolerance = 0.85f; ?

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:124: }
It seems like if we're going to clear fDirty out here we should also be clearing
fDirtyRect here too?

[jvanverth1, 2014-05-12 20:44:04]

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp
File src/gpu/GrAtlas.cpp (right):

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:59: // create backing memory on first use
On 2014/05/12 19:45:52, robertphillips wrote:
> // Once the plot is nearly full we will revert to uploading each subimage
> individually

Done.

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:68: if (NULL != fPlotData) {
On 2014/05/12 19:45:52, robertphillips wrote:
> const unsigned char* ?

Done.

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:107: int rowBytes = fBytesPerPixel*fRects->width();
On 2014/05/12 19:45:52, robertphillips wrote:
> const unsigned char* ?

Done.

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:119: // at a time, so free up the memory and upload any new
images directly.
On 2014/05/12 19:45:52, robertphillips wrote:
> static const int kNearlyFullTolerance = 0.85f; ?

Done.

https://codereview.chromium.org/269423007/diff/50001/src/gpu/GrAtlas.cpp#newc...
src/gpu/GrAtlas.cpp:124: }
On 2014/05/12 19:45:52, robertphillips wrote:
> It seems like if we're going to clear fDirty out here we should also be
clearing
> fDirtyRect here too?

Cleaned up. We shouldn't hit the 'if' block unless a texture is assigned, so all
we need to check is fDirty, and can clear both in there.

[jvanverth1, 2014-05-14 14:21:36]

Added a flag to GrAtlasMgr and GrPlot to enable batching. GrLayerCache will not
use batching, while GrTextStrike will.

PTAL

[robertphillips, 2014-05-14 14:46:18]

lgtm + 1 question

https://codereview.chromium.org/269423007/diff/110001/src/gpu/GrAtlas.cpp
File src/gpu/GrAtlas.cpp (right):

https://codereview.chromium.org/269423007/diff/110001/src/gpu/GrAtlas.cpp#new...
src/gpu/GrAtlas.cpp:106: void GrPlot::uploadToTexture() {
SkASSERT(fBatchUploads); ?

[jvanverth1, 2014-05-14 15:01:32]

https://codereview.chromium.org/269423007/diff/110001/src/gpu/GrAtlas.cpp
File src/gpu/GrAtlas.cpp (right):

https://codereview.chromium.org/269423007/diff/110001/src/gpu/GrAtlas.cpp#new...
src/gpu/GrAtlas.cpp:106: void GrPlot::uploadToTexture() {
On 2014/05/14 14:46:19, robertphillips wrote:
> SkASSERT(fBatchUploads); ?

Done.

[jvanverth1, 2014-05-14 15:01:38]

The CQ bit was checked by jvanverth@google.com

[commit-bot: I haz the power, 2014-05-14 15:01:50]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/jvanverth@google.com/269423007/150001

[commit-bot: I haz the power, 2014-05-14 15:15:04]

Change committed as 14729