Fix memory leak when drawing text in non-common script

When the fontEngine() cached was updated for new parameters, we
would overwrite the cached engine, but not deref the old cached engine,
thus it would never be deleted.

Change-Id: I3b88698712e468ffa634bd98019a7871662cc363
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index 3137de6a3b..8fc317627d 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -1907,12 +1907,17 @@ QFontEngine *QTextEngine::fontEngine(const QScriptItem &si, QFixed *ascent, QFix
                     font.setPixelSize((font.pixelSize() * 2) / 3);
                 scaledEngine = font.d->engineForScript(script);
             }
-            feCache.prevFontEngine = engine;
             if (engine)
                 engine->ref.ref();
-            feCache.prevScaledFontEngine = scaledEngine;
+            if (feCache.prevFontEngine)
+                releaseCachedFontEngine(feCache.prevFontEngine);
+            feCache.prevFontEngine = engine;
+
             if (scaledEngine)
                 scaledEngine->ref.ref();
+            if (feCache.prevScaledFontEngine)
+                releaseCachedFontEngine(feCache.prevScaledFontEngine);
+            feCache.prevScaledFontEngine = scaledEngine;
             feCache.prevScript = script;
             feCache.prevPosition = si.position;
             feCache.prevLength = length(&si);
@@ -1922,9 +1927,11 @@ QFontEngine *QTextEngine::fontEngine(const QScriptItem &si, QFixed *ascent, QFix
             engine = feCache.prevFontEngine;
         else {
             engine = font.d->engineForScript(script);
-            feCache.prevFontEngine = engine;
             if (engine)
                 engine->ref.ref();
+            if (feCache.prevFontEngine)
+                releaseCachedFontEngine(feCache.prevFontEngine);
+            feCache.prevFontEngine = engine;
             feCache.prevScript = script;
             feCache.prevPosition = -1;
             feCache.prevLength = -1;