Support toggling antialiasing for Text and Rectangle.

Task-number: QTBUG-27968
Task-number: QTBUG-34366
Change-Id: Ic446ff4470abf21696e1764f902bd71e79762697
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

7 files changed, 99 insertions, 19 deletions

diff --git a/src/quick/items/context2d/qquickcanvasitem.cpp b/src/quick/items/context2d/qquickcanvasitem.cpp
index ba3592986c..ee1b5f316c 100644
--- a/src/quick/items/context2d/qquickcanvasitem.cpp
+++ b/src/quick/items/context2d/qquickcanvasitem.cpp
@@ -196,7 +196,7 @@ QQuickCanvasItemPrivate::QQuickCanvasItemPrivate()
     , renderTarget(QQuickCanvasItem::Image)
     , renderStrategy(QQuickCanvasItem::Cooperative)
 {
-    antialiasing = true;
+    implicitAntialiasing = true;
 }
 
 QQuickCanvasItemPrivate::~QQuickCanvasItemPrivate()
@@ -654,7 +654,7 @@ void QQuickCanvasItem::updatePolish()
     Q_D(QQuickCanvasItem);
 
     if (d->context && d->renderStrategy != QQuickCanvasItem::Cooperative)
-        d->context->prepare(d->canvasSize.toSize(), d->tileSize, d->canvasWindow.toRect(), d->dirtyRect.toRect(), d->smooth, d->antialiasing);
+        d->context->prepare(d->canvasSize.toSize(), d->tileSize, d->canvasWindow.toRect(), d->dirtyRect.toRect(), d->smooth, antialiasing());
 
     if (d->animationCallbacks.size() > 0 && isVisible()) {
         QMap<int, QV4::PersistentValue> animationCallbacks = d->animationCallbacks;
@@ -708,7 +708,7 @@ QSGNode *QQuickCanvasItem::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData
         node->setFiltering(QSGTexture::Nearest);
 
     if (d->renderStrategy == QQuickCanvasItem::Cooperative) {
-        d->context->prepare(d->canvasSize.toSize(), d->tileSize, d->canvasWindow.toRect(), d->dirtyRect.toRect(), d->smooth, d->antialiasing);
+        d->context->prepare(d->canvasSize.toSize(), d->tileSize, d->canvasWindow.toRect(), d->dirtyRect.toRect(), d->smooth, antialiasing());
         d->context->flush();
     }
 
diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 65322f6de4..96797a7588 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -2703,6 +2703,8 @@ QQuickItemPrivate::QQuickItemPrivate()
     , culled(false)
     , hasCursor(false)
     , activeFocusOnTab(false)
+    , implicitAntialiasing(false)
+    , antialiasingValid(false)
     , dirtyAttributes(0)
     , nextDirtyItem(0)
     , prevDirtyItem(0)
@@ -5477,6 +5479,9 @@ void QQuickItemPrivate::itemChange(QQuickItem::ItemChange change, const QQuickIt
             }
         }
         break;
+    case QQuickItem::ItemAntialiasingHasChanged:
+        q->itemChange(change, data);
+        break;
     }
 }
 
@@ -5570,37 +5575,65 @@ void QQuickItem::setActiveFocusOnTab(bool activeFocusOnTab)
 /*!
     \qmlproperty bool QtQuick::Item::antialiasing
 
-    Primarily used in Rectangle and image based elements to decide if the item should
-    use antialiasing or not. Items with antialiasing enabled require more memory and
-    are potentially slower to render.
+    Used by visual elements to decide if the item should use antialiasing or not.
+    In some cases items with antialiasing require more memory and are potentially
+    slower to render (see \l {Antialiasing} for more details).
 
-    The default is false.
+    The default is false, but may be overridden by derived elements.
 */
 /*!
     \property QQuickItem::antialiasing
     \brief Specifies whether the item is antialiased or not
 
-    Primarily used in Rectangle and image based elements to decide if the item should
-    use antialiasing or not. Items with antialiasing enabled require more memory and
-    are potentially slower to render.
+    Used by visual elements to decide if the item should use antialiasing or not.
+    In some cases items with antialiasing require more memory and are potentially
+    slower to render (see \l {Antialiasing} for more details).
 
-    The default is false.
+    The default is false, but may be overridden by derived elements.
 */
 bool QQuickItem::antialiasing() const
 {
     Q_D(const QQuickItem);
-    return d->antialiasing;
+    return d->antialiasingValid ? d->antialiasing : d->implicitAntialiasing;
 }
-void QQuickItem::setAntialiasing(bool antialiasing)
+
+void QQuickItem::setAntialiasing(bool aa)
 {
     Q_D(QQuickItem);
-    if (d->antialiasing == antialiasing)
+
+    bool changed = (aa != antialiasing());
+    d->antialiasingValid = true;
+
+    if (!changed)
         return;
 
-    d->antialiasing = antialiasing;
+    d->antialiasing = aa;
     d->dirty(QQuickItemPrivate::Antialiasing);
 
-    emit antialiasingChanged(antialiasing);
+    d->itemChange(ItemAntialiasingHasChanged, d->antialiasing);
+
+    emit antialiasingChanged(antialiasing());
+}
+
+void QQuickItem::resetAntialiasing()
+{
+    Q_D(QQuickItem);
+    if (!d->antialiasingValid)
+        return;
+
+    d->antialiasingValid = false;
+
+    if (d->implicitAntialiasing != d->antialiasing)
+        emit antialiasingChanged(antialiasing());
+}
+
+void QQuickItemPrivate::setImplicitAntialiasing(bool antialiasing)
+{
+    Q_Q(QQuickItem);
+    bool prev = q->antialiasing();
+    implicitAntialiasing = antialiasing;
+    if (componentComplete && (q->antialiasing() != prev))
+        emit q->antialiasingChanged(q->antialiasing());
 }
 
 /*!
diff --git a/src/quick/items/qquickitem.h b/src/quick/items/qquickitem.h
index 2500a2d33a..c666af2729 100644
--- a/src/quick/items/qquickitem.h
+++ b/src/quick/items/qquickitem.h
@@ -141,7 +141,7 @@ class Q_QUICK_EXPORT QQuickItem : public QObject, public QQmlParserStatus
     Q_PROPERTY(QQmlListProperty<QQuickTransform> transform READ transform DESIGNABLE false FINAL)
 
     Q_PROPERTY(bool smooth READ smooth WRITE setSmooth NOTIFY smoothChanged)
-    Q_PROPERTY(bool antialiasing READ antialiasing WRITE setAntialiasing NOTIFY antialiasingChanged)
+    Q_PROPERTY(bool antialiasing READ antialiasing WRITE setAntialiasing NOTIFY antialiasingChanged RESET resetAntialiasing)
     Q_PROPERTY(qreal implicitWidth READ implicitWidth WRITE setImplicitWidth NOTIFY implicitWidthChanged)
     Q_PROPERTY(qreal implicitHeight READ implicitHeight WRITE setImplicitHeight NOTIFY implicitHeightChanged)
 
@@ -172,7 +172,8 @@ public:
         ItemParentHasChanged,      // value.item
         ItemOpacityHasChanged,     // value.realValue
         ItemActiveFocusHasChanged, // value.boolValue
-        ItemRotationHasChanged     // value.realValue
+        ItemRotationHasChanged,    // value.realValue
+        ItemAntialiasingHasChanged // value.boolValue
     };
 
     union ItemChangeData {
@@ -267,6 +268,7 @@ public:
 
     bool antialiasing() const;
     void setAntialiasing(bool);
+    void resetAntialiasing();
 
     Flags flags() const;
     void setFlag(Flag flag, bool enabled = true);
diff --git a/src/quick/items/qquickitem_p.h b/src/quick/items/qquickitem_p.h
index ccf949ee8b..3987ff0cfb 100644
--- a/src/quick/items/qquickitem_p.h
+++ b/src/quick/items/qquickitem_p.h
@@ -422,6 +422,8 @@ public:
     bool hasCursor:1;
     // Bit 32
     bool activeFocusOnTab:1;
+    bool implicitAntialiasing:1;
+    bool antialiasingValid:1;
 
     enum DirtyType {
         TransformOrigin         = 0x00000001,
@@ -521,6 +523,8 @@ public:
     virtual void implicitWidthChanged();
     virtual void implicitHeightChanged();
 
+    void setImplicitAntialiasing(bool antialiasing);
+
     void resolveLayoutMirror();
     void setImplicitLayoutMirror(bool mirror, bool inherit);
     void setLayoutMirror(bool mirror);
diff --git a/src/quick/items/qquickrectangle.cpp b/src/quick/items/qquickrectangle.cpp
index dd482eddb7..d6323026e7 100644
--- a/src/quick/items/qquickrectangle.cpp
+++ b/src/quick/items/qquickrectangle.cpp
@@ -321,6 +321,16 @@ void QQuickRectangle::doUpdate()
 }
 
 /*!
+    \qmlproperty bool QtQuick::Rectangle::antialiasing
+
+    Used to decide if the Rectangle should use antialiasing or not.
+    \l {Antialiasing} provides information on the performance implications
+    of this property.
+
+    The default is true for Rectangles with a radius, and false otherwise.
+*/
+
+/*!
     \qmlproperty int QtQuick::Rectangle::border.width
     \qmlproperty color QtQuick::Rectangle::border.color
 
@@ -408,6 +418,8 @@ void QQuickRectangle::setRadius(qreal radius)
         return;
 
     d->radius = radius;
+    d->setImplicitAntialiasing(radius != 0.0);
+
     update();
     emit radiusChanged();
 }
@@ -475,7 +487,7 @@ QSGNode *QQuickRectangle::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData
     }
 
     rectangle->setRadius(d->radius);
-    rectangle->setAntialiasing(d->antialiasing || d->radius > 0);
+    rectangle->setAntialiasing(antialiasing());
 
     QGradientStops stops;
     if (d->gradient) {
diff --git a/src/quick/items/qquicktext.cpp b/src/quick/items/qquicktext.cpp
index 1d2e70d519..9d11bfb4ea 100644
--- a/src/quick/items/qquicktext.cpp
+++ b/src/quick/items/qquicktext.cpp
@@ -88,6 +88,7 @@ QQuickTextPrivate::QQuickTextPrivate()
     , truncated(false), hAlignImplicit(true), rightToLeftText(false)
     , layoutTextElided(false), textHasChanged(true), needToUpdateLayout(false), formatModifiesFontSize(false)
 {
+    implicitAntialiasing = true;
 }
 
 QQuickTextPrivate::ExtraData::ExtraData()
@@ -298,6 +299,15 @@ qreal QQuickTextPrivate::getImplicitHeight() const
 }
 
 /*!
+    \qmlproperty bool QtQuick::Text::antialiasing
+
+    Used to decide if the Text should use antialiasing or not. Only Text
+    with renderType of Text.NativeRendering can disable antialiasing.
+
+    The default is true.
+*/
+
+/*!
     \qmlproperty enumeration QtQuick::Text::renderType
 
     Override the default rendering type for this component.
@@ -1465,6 +1475,9 @@ void QQuickText::setFont(const QFont &font)
     QFont oldFont = d->font;
     d->font = font;
 
+    if (!antialiasing())
+        d->font.setStyleStrategy(QFont::NoAntialias);
+
     if (d->font.pointSizeF() != -1) {
         // 0.5pt resolution
         qreal size = qRound(d->font.pointSizeF()*2.0);
@@ -1484,6 +1497,21 @@ void QQuickText::setFont(const QFont &font)
     emit fontChanged(d->sourceFont);
 }
 
+void QQuickText::itemChange(ItemChange change, const ItemChangeData &value)
+{
+    Q_D(QQuickText);
+    Q_UNUSED(value);
+    if (change == ItemAntialiasingHasChanged) {
+        if (!antialiasing())
+            d->font.setStyleStrategy(QFont::NoAntialias);
+        else
+            d->font.setStyleStrategy(QFont::PreferAntialias);
+        d->implicitWidthValid = false;
+        d->implicitHeightValid = false;
+        d->updateLayout();
+    }
+}
+
 /*!
     \qmlproperty string QtQuick::Text::text
 
diff --git a/src/quick/items/qquicktext_p.h b/src/quick/items/qquicktext_p.h
index 489ef58344..d55dc7e287 100644
--- a/src/quick/items/qquicktext_p.h
+++ b/src/quick/items/qquicktext_p.h
@@ -241,6 +241,7 @@ Q_SIGNALS:
 protected:
     void mousePressEvent(QMouseEvent *event);
     void mouseReleaseEvent(QMouseEvent *event);
+    virtual void itemChange(ItemChange change, const ItemChangeData &value);
     virtual void geometryChanged(const QRectF &newGeometry,
                                  const QRectF &oldGeometry);
     virtual QSGNode *updatePaintNode(QSGNode *, UpdatePaintNodeData *);