Fix assertion with certain Text items when rendering with Metal

Caused by a -1 vs. 0 discrepancy between the QRhi and the OpenGL
glyph caches. width() and height() are expected to return 0 for
an empty image, but this we forgot to honor in the QRhi version.
That returned the width or height of a QSize, and those are
-1 when default constructed. (there are good reasons for that,
it just happens to not match the non-QSize-based code path here)

Change-Id: Idda0d2f77430abea79d4004b765077032e06954b
Fixes: QTBUG-79533
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/quick/scenegraph/qsgrhitextureglyphcache_p.h b/src/quick/scenegraph/qsgrhitextureglyphcache_p.h
index a7374d91a4..49854a596e 100644
--- a/src/quick/scenegraph/qsgrhitextureglyphcache_p.h
+++ b/src/quick/scenegraph/qsgrhitextureglyphcache_p.h
@@ -75,8 +75,10 @@ public:
     QRhiTexture *texture() const { return m_texture; }
     void commitResourceUpdates(QRhiResourceUpdateBatch *mergeInto);
 
-    int width() const { return m_size.width(); }
-    int height() const { return m_size.height(); }
+    // Clamp the default -1 width and height to 0 for compatibility with
+    // QOpenGLTextureGlyphCache.
+    int width() const { return qMax(0, m_size.width()); }
+    int height() const { return qMax(0, m_size.height()); }
 
     bool eightBitFormatIsAlphaSwizzled() const;