Adjust QSGTexture comparisonKey type

The original choice was int, simply following textureId(). This was later
deemed insufficient: instead of a GLuint, the value is now often a 64-bit
value (on 64 bit systems), based on a pointer, since the identity of a texture
in the RHI world is the QRhiTexture* itself. In a custom texture implementation
it is likely that the value here is the value of a native object handle, either
a pointer or some 32 or 64 bit integer.

Inspired by the recent QSGTexture::NativeTexture struct change (void* -> quint64),
switch to a qint64 which is big enough to hold all these without truncation.

We choose a signed value here, in order to allow for the following pattern that
is widespread in material compare() implementations:
if (qint64 diff = m_texture->comparisonKey() - other->texture()->comparisonKey())
  return diff;

Fixes: QTBUG-83769
Change-Id: I8bdae8cd835282358ded53b3703142b8f26e4400
Reviewed-by: Christian Strømme <christian.stromme@qt.io>

0 files changed, 0 insertions, 0 deletions