Fix the font engines leaking

1. when there were some engines with ref > 1 in the cache, prior to calling
   QFontDatabase::{add,remove}ApplicationFont()/removeAllApplicationFonts()
   (QFontCache::clear() has never decreased engine's cache_count);
2. when the QFontEngineData's engine is not in cache i.e. the Box or Test font engine
   (~QFontEngineData() didn't free engines it keeps).

Instead of using the font engine's (external) "cache_count" counter,
QFontCache now references a given font engine every time it is inserted to
the cache and dereferences exactly that number of times in clear().

Change-Id: I87677ebd24c1f4a81a53526f2e726e596b043c61
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/src/gui/text/qrawfont.cpp b/src/gui/text/qrawfont.cpp
index 5781b49eab..f52b46eeae 100644
--- a/src/gui/text/qrawfont.cpp
+++ b/src/gui/text/qrawfont.cpp
@@ -738,8 +738,7 @@ void QRawFont::setPixelSize(qreal pixelSize)
     if (d->fontEngine != 0)
         d->fontEngine->ref.ref();
 
-    oldFontEngine->ref.deref();
-    if (oldFontEngine->cache_count == 0 && oldFontEngine->ref.load() == 0)
+    if (!oldFontEngine->ref.deref())
         delete oldFontEngine;
 }
 
@@ -750,8 +749,7 @@ void QRawFontPrivate::cleanUp()
 {
     platformCleanUp();
     if (fontEngine != 0) {
-        fontEngine->ref.deref();
-        if (fontEngine->cache_count == 0 && fontEngine->ref.load() == 0)
+        if (!fontEngine->ref.deref())
             delete fontEngine;
         fontEngine = 0;
     }