Fixed missing text when using static text items in GL 2 engine.

When the context is destroyed and recreated, we end up with a new glyph
cache, but we only recreate the vertex arrays for the very first static
text item. We need to keep track of the glyph cache in each text item,
so that we can recreate the vertex arrays and re-populate the cache
accordingly. As the pointer might be the same after the glyph cache is
recreated, we need to use serial numbers instead.

We also need to re-create the cache when the context pointer has been
invalidated, so that the static text items also get invalidated, and
the texture glyph cache gets repopulated.

Reviewed-by: Eskil Abrahamsen Blomfeldt

3 files changed, 14 insertions, 5 deletions

diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index ad2852e..cda31e5 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -1489,7 +1489,7 @@ namespace {
     {
     public:
         QOpenGLStaticTextUserData()
-            : QStaticTextUserData(OpenGLUserData), cacheSize(0, 0)
+            : QStaticTextUserData(OpenGLUserData), cacheSize(0, 0), cacheSerialNumber(0)
         {
         }
 
@@ -1501,6 +1501,7 @@ namespace {
         QGL2PEXVertexArray vertexCoordinateArray;
         QGL2PEXVertexArray textureCoordinateArray;
         QFontEngineGlyphCache::Type glyphType;
+        int cacheSerialNumber;
     };
 
 }
@@ -1518,12 +1519,10 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(QFontEngineGlyphCache::Type glyp
 
     QGLTextureGlyphCache *cache =
         (QGLTextureGlyphCache *) staticTextItem->fontEngine()->glyphCache(ctx, glyphType, QTransform());
-    if (!cache || cache->cacheType() != glyphType) {
+    if (!cache || cache->cacheType() != glyphType || cache->context() == 0) {
         cache = new QGLTextureGlyphCache(ctx, glyphType, QTransform());
         staticTextItem->fontEngine()->setGlyphCache(ctx, cache);
         recreateVertexArrays = true;
-    } else if (cache->context() == 0) { // Old context has been destroyed, new context has same ptr value
-        cache->setContext(ctx);
     }
 
     if (staticTextItem->userDataNeedsUpdate) {
@@ -1534,8 +1533,11 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(QFontEngineGlyphCache::Type glyp
         recreateVertexArrays = true;
     } else {
         QOpenGLStaticTextUserData *userData = static_cast<QOpenGLStaticTextUserData *>(staticTextItem->userData());
-        if (userData->glyphType != glyphType)
+        if (userData->glyphType != glyphType) {
             recreateVertexArrays = true;
+        } else if (userData->cacheSerialNumber != cache->serialNumber()) {
+            recreateVertexArrays = true;
+        }
     }
 
     // We only need to update the cache with new glyphs if we are actually going to recreate the vertex arrays.
@@ -1580,6 +1582,7 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(QFontEngineGlyphCache::Type glyp
         }
 
         userData->glyphType = glyphType;
+        userData->cacheSerialNumber = cache->serialNumber();
 
         // Use cache if backend optimizations is turned on
         vertexCoordinates = &userData->vertexCoordinateArray;
diff --git a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
index 58c78ec..312d66f 100644
--- a/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
+++ b/src/opengl/gl2paintengineex/qtextureglyphcache_gl.cpp
@@ -52,12 +52,15 @@ QT_BEGIN_NAMESPACE
 extern Q_GUI_EXPORT bool qt_cleartype_enabled;
 #endif
 
+QBasicAtomicInt qgltextureglyphcache_serial_number = Q_BASIC_ATOMIC_INITIALIZER(1);
+
 QGLTextureGlyphCache::QGLTextureGlyphCache(QGLContext *context, QFontEngineGlyphCache::Type type, const QTransform &matrix)
     : QImageTextureGlyphCache(type, matrix)
     , ctx(0)
     , m_width(0)
     , m_height(0)
     , m_filterMode(Nearest)
+    , m_serialNumber(qgltextureglyphcache_serial_number.fetchAndAddRelaxed(1))
 {
     setContext(context);
 }
diff --git a/src/opengl/gl2paintengineex/qtextureglyphcache_gl_p.h b/src/opengl/gl2paintengineex/qtextureglyphcache_gl_p.h
index 1c1b7c4..2eb4e65 100644
--- a/src/opengl/gl2paintengineex/qtextureglyphcache_gl_p.h
+++ b/src/opengl/gl2paintengineex/qtextureglyphcache_gl_p.h
@@ -83,6 +83,8 @@ public:
 
     inline void setPaintEnginePrivate(QGL2PaintEngineExPrivate *p) { pex = p; }
 
+    inline int serialNumber() const { return m_serialNumber; }
+
     enum FilterMode {
         Nearest,
         Linear
@@ -140,6 +142,7 @@ private:
     QGLShaderProgram *m_program;
 
     FilterMode m_filterMode;
+    int m_serialNumber;
 };
 
 QT_END_NAMESPACE