Missing glyphs in GL when scaling QStaticText and QML text items

Since scaled text is backed by an A8 glyph cache, it needs to repopulate
even if it has previously populated the cache for the unscaled text.
This means that we need to record in the userData that the type of the
cache is not the same as the last time. Otherwise the A8 version of the
cache will only be updated when it's created and when the text actually
changes, leading to glyphs missing on screen when zooming text using
a scale.

Task-number: QTBUG-16012
Reviewed-by: Gunnar

1 files changed, 13 insertions, 5 deletions

diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index 7045fe9..4a64f39 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -1464,6 +1464,7 @@ namespace {
         QSize cacheSize;
         QGL2PEXVertexArray vertexCoordinateArray;
         QGL2PEXVertexArray textureCoordinateArray;
+        QFontEngineGlyphCache::Type glyphType;
     };
 
 }
@@ -1489,12 +1490,17 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(QFontEngineGlyphCache::Type glyp
         cache->setContext(ctx);
     }
 
-    if (staticTextItem->userDataNeedsUpdate)
+    if (staticTextItem->userDataNeedsUpdate) {
         recreateVertexArrays = true;
-    else if (staticTextItem->userData() == 0)
+    } else if (staticTextItem->userData() == 0) {
         recreateVertexArrays = true;
-    else if (staticTextItem->userData()->type != QStaticTextUserData::OpenGLUserData)
+    } else if (staticTextItem->userData()->type != QStaticTextUserData::OpenGLUserData) {
         recreateVertexArrays = true;
+    } else {
+        QOpenGLStaticTextUserData *userData = static_cast<QOpenGLStaticTextUserData *>(staticTextItem->userData());
+        if (userData->glyphType != glyphType)
+            recreateVertexArrays = true;
+    }
 
     // We only need to update the cache with new glyphs if we are actually going to recreate the vertex arrays.
     // If the cache size has changed, we do need to regenerate the vertices, but we don't need to repopulate the
@@ -1506,8 +1512,8 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(QFontEngineGlyphCache::Type glyp
 	    // No space in cache. We need to clear the cache and try again
             cache->clear();
             cache->populate(staticTextItem->fontEngine(), staticTextItem->numGlyphs,
-			    staticTextItem->glyphs, staticTextItem->glyphPositions);
-	}
+                            staticTextItem->glyphs, staticTextItem->glyphPositions);
+        }
     }
 
     if (cache->width() == 0 || cache->height() == 0)
@@ -1537,6 +1543,8 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(QFontEngineGlyphCache::Type glyp
             userData = static_cast<QOpenGLStaticTextUserData*>(staticTextItem->userData());
         }
 
+        userData->glyphType = glyphType;
+
         // Use cache if backend optimizations is turned on
         vertexCoordinates = &userData->vertexCoordinateArray;
         textureCoordinates = &userData->textureCoordinateArray;