Fix up mac capturer to flip image.

Fix up mac capturer to flip image.


BUG=74078
TEST=Connect to a mac host. Image should come right side up.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=76713

[dmac, 2011-03-03 01:32:40]

Mind taking a look gents?

[Alpha Left Google, 2011-03-03 01:43:33]

I would like to avoid the extra memory copy, but I'd say LGTM if we have a bug
filed for this.

I was thinking of doing a glScaled(1, -1, 1); before glReadPixels() to see if it
has any effects..

Another way you can try is to provide a negative stride to glPixelStorei(),
e.g.:
glPixelStorei( GL_UNPACK_ROW_LENGTH, -bytes_per_row_);

and then change glReadPixels() to:

 glReadPixels(0, 0, width(), height(), GL_BGRA, GL_UNSIGNED_BYTE,
               buffers_[current_buffer_].get() + bytes_per_row_ * (height() -
1));

http://codereview.chromium.org/6610007/diff/1/remoting/host/capturer_mac.cc
File remoting/host/capturer_mac.cc (right):

http://codereview.chromium.org/6610007/diff/1/remoting/host/capturer_mac.cc#n...
remoting/host/capturer_mac.cc:112: for (int x = 0; x < w; ++x) {
Do a memcpy instead of doing yourself, memcpy is pretty optimized.

[Alpha Left Google, 2011-03-03 01:45:47]

Note that OpenGL API doesn't state very clear what happen if
GL_UNPACK_ROW_LENGTH is negative, but I think it's worth trying..

[ajwong, 2011-03-03 01:46:54]

betcha it's platform/driver dependent...

On Wed, Mar 2, 2011 at 5:45 PM, <hclam@chromium.org> wrote:

> Note that OpenGL API doesn't state very clear what happen if
> GL_UNPACK_ROW_LENGTH is negative, but I think it's worth trying..
>
>
> http://codereview.chromium.org/6610007/
>

[dmaclach1, 2011-03-03 04:14:18]

On Wed, Mar 2, 2011 at 5:45 PM,  <hclam@chromium.org> wrote:
> Note that OpenGL API doesn't state very clear what happen if
> GL_UNPACK_ROW_LENGTH is negative, but I think it's worth trying..
>
> http://codereview.chromium.org/6610007/
>

I'd already checked with Apple OpenGL folks. Not supported, and
glScaled(1, -1, 1) has no effect on glReadPixels. I'll switch back to
memcpy.

[Jamie, 2011-03-03 10:30:53]

LGTM with Alpha's comments.