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>

2 files changed, 2 insertions, 2 deletions

diff --git a/src/plugins/scenegraph/openvg/qsgopenvglayer.cpp b/src/plugins/scenegraph/openvg/qsgopenvglayer.cpp
index b03168b334..3ecf0dcb31 100644
--- a/src/plugins/scenegraph/openvg/qsgopenvglayer.cpp
+++ b/src/plugins/scenegraph/openvg/qsgopenvglayer.cpp
@@ -313,7 +313,7 @@ void QSGOpenVGLayer::grab()
         markDirtyTexture(); // Continuously update if 'live' and 'recursive'.
 }
 
-int QSGOpenVGLayerPrivate::comparisonKey() const
+qint64 QSGOpenVGLayerPrivate::comparisonKey() const
 {
     return 0;
 }
diff --git a/src/plugins/scenegraph/openvg/qsgopenvglayer.h b/src/plugins/scenegraph/openvg/qsgopenvglayer.h
index f2763463cd..1d52310f5c 100644
--- a/src/plugins/scenegraph/openvg/qsgopenvglayer.h
+++ b/src/plugins/scenegraph/openvg/qsgopenvglayer.h
@@ -116,7 +116,7 @@ class QSGOpenVGLayerPrivate : public QSGTexturePrivate
 {
     Q_DECLARE_PUBLIC(QSGOpenVGLayer)
 public:
-    int comparisonKey() const override;
+    qint64 comparisonKey() const override;
 };
 
 QT_END_NAMESPACE