Let Item.layer.samplerName be a QByteArray instead of QString.

Both Qt's property system and OpenGL shaders use 8-bit characters,
so there is no need to use a QString for samplerName.

Change-Id: I8cc29c74adb5d71a34cc99d9ecebbbba8b554cdf
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

src/quick/items/qquickitem.cpp

@@ -5384,11 +5384,11 @@ QQuickItemLayer::QQuickItemLayer(QQuickItem *item)
     , m_componentComplete(true)
     , m_wrapMode(QQuickShaderEffectSource::ClampToEdge)
     , m_format(QQuickShaderEffectSource::RGBA)
+    , m_name("source")
     , m_effectComponent(0)
     , m_effect(0)
     , m_effectSource(0)
 {
-    m_name = QLatin1String("source");
 }
 
 QQuickItemLayer::~QQuickItemLayer()
@@ -5509,7 +5509,7 @@ void QQuickItemLayer::activateEffect()
         m_effect->stackAfter(m_effectSource);
     }
     m_effect->setVisible(m_item->isVisible());
-    m_effect->setProperty(m_name.toLatin1(), qVariantFromValue<QObject *>(m_effectSource));
+    m_effect->setProperty(m_name, qVariantFromValue<QObject *>(m_effectSource));
 }
 
 void QQuickItemLayer::deactivateEffect()
@@ -5724,12 +5724,12 @@ void QQuickItemLayer::setWrapMode(QQuickShaderEffectSource::WrapMode mode)
     \sa effect, ShaderEffect
  */
 
-void QQuickItemLayer::setName(const QString &name) {
+void QQuickItemLayer::setName(const QByteArray &name) {
     if (m_name == name)
         return;
     if (m_effect) {
-        m_effect->setProperty(m_name.toLatin1(), QVariant());
-        m_effect->setProperty(name.toLatin1(), qVariantFromValue<QObject *>(m_effectSource));
+        m_effect->setProperty(m_name, QVariant());
+        m_effect->setProperty(name, qVariantFromValue<QObject *>(m_effectSource));
     }
     m_name = name;
     emit nameChanged(name);

src/quick/items/qquickitem_p.h

@@ -148,7 +148,7 @@ class QQuickItemLayer : public QObject, public QQuickItemChangeListener
     Q_PROPERTY(bool smooth READ smooth WRITE setSmooth NOTIFY smoothChanged)
     Q_PROPERTY(QQuickShaderEffectSource::WrapMode wrapMode READ wrapMode WRITE setWrapMode NOTIFY wrapModeChanged)
     Q_PROPERTY(QQuickShaderEffectSource::Format format READ format WRITE setFormat NOTIFY formatChanged)
-    Q_PROPERTY(QString samplerName READ name WRITE setName NOTIFY nameChanged)
+    Q_PROPERTY(QByteArray samplerName READ name WRITE setName NOTIFY nameChanged)
     Q_PROPERTY(QDeclarativeComponent *effect READ effect WRITE setEffect NOTIFY effectChanged)
 public:
     QQuickItemLayer(QQuickItem *item);
@@ -178,8 +178,8 @@ class QQuickItemLayer : public QObject, public QQuickItemChangeListener
     QQuickShaderEffectSource::WrapMode wrapMode() const { return m_wrapMode; }
     void setWrapMode(QQuickShaderEffectSource::WrapMode mode);
 
-    QString name() const { return m_name; }
-    void setName(const QString &name);
+    QByteArray name() const { return m_name; }
+    void setName(const QByteArray &name);
 
     QDeclarativeComponent *effect() const { return m_effectComponent; }
     void setEffect(QDeclarativeComponent *effect);
@@ -202,7 +202,7 @@ class QQuickItemLayer : public QObject, public QQuickItemChangeListener
     void sizeChanged(const QSize &size);
     void mipmapChanged(bool mipmap);
     void wrapModeChanged(QQuickShaderEffectSource::WrapMode mode);
-    void nameChanged(const QString &name);
+    void nameChanged(const QByteArray &name);
     void effectChanged(QDeclarativeComponent *component);
     void smoothChanged(bool smooth);
     void formatChanged(QQuickShaderEffectSource::Format format);
@@ -223,7 +223,7 @@ class QQuickItemLayer : public QObject, public QQuickItemChangeListener
     QQuickShaderEffectSource::Format m_format;
     QSize m_size;
     QRectF m_sourceRect;
-    QString m_name;
+    QByteArray m_name;
     QDeclarativeComponent *m_effectComponent;
     QQuickItem *m_effect;
     QQuickShaderEffectSource *m_effectSource;