D8664: [platforms/drm] Move cursor dumb buffers to Output

[David Edmundson]

davidedmundson requested changes to this revision.
davidedmundson added a comment.
This revision now requires changes to proceed.


  Idea is good. Few minor comments.
  
  ----
  
  I might be wrong, but it looks to me that:
  
  updateCursor now swaps m_cursorIndex which is a signifcant behaviour change from the old separate setCursor/updateCursor
  
  therefore if we ever call
  
  showCursor
  updateCursor
  updateCursor
  
  you'd end up painting into the front buffer which is bad.
  
  I can see a few code paths that do this.

INLINE COMMENTS

> drm_output.cpp:125
> +    c->fill(Qt::transparent);
> +    if (m_orientation == Qt::InvertedLandscapeOrientation) {
> +        cursorImage = cursorImage.mirrored(true, true);

This will be much faster is you set a matrix (setWorldTransform) on the QPainter.

Then it will do the transformation inside drawImage and get rid of the intermediate data copy

> drm_output.cpp:960
> +            // the cursor might need to get rotated
> +            updateCursor();
>              // TODO: forward to OutputInterface and OutputDeviceInterface

this needs a showCursor() too to be useful

> drm_output.cpp:1164
> +        }
> +        m_cursor[index]->image()->fill(Qt::transparent);
> +        return true;

You fill it transparent before every paint anyway

> drm_output.h:181
>      } m_lastWorkingState;
> +    DrmDumbBuffer *m_cursor[2];
> +    int m_cursorIndex = 0;

Not that you need to, but:

m_cursor[2] = {nullptr,nullptr}

should work just fine instead of doing it in the ctor

REPOSITORY
  R108 KWin

REVISION DETAIL
  https://phabricator.kde.org/D8664

To: graesslin, #kwin, #plasma, davidedmundson
Cc: davidedmundson, plasma-devel, kwin, ZrenBot, progwolff, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol, mart
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