FGQCanvas clipping / default text color fixes

Also fix some compiler warnings, but the main thing is text now
defaults to white correctly if no color was set explicitly, and
local/parent clip-reference-frames are supported.

utils/fgqcanvas/fgcanvaselement.cpp

@@ -175,30 +175,34 @@ void FGCanvasElement::paint(FGCanvasPaintContext *context) const
     QPainter* p = context->painter();
     p->save();
 
+    QTransform combined = combinedTransform();
 
     if (_hasClip)
     {
+        QTransform t = p->transform();
+
         // clip is defined in the global coordinate system
-        if (_clipFrame != ReferenceFrame::GLOBAL) {
-            qWarning() << Q_FUNC_INFO << "implement support for non-global clips";
+        if (_clipFrame == ReferenceFrame::GLOBAL) {
+            // this rpelaces the transform entirely
+            p->setTransform(context->globalCoordinateTransform());
+        } else if (_clipFrame == ReferenceFrame::LOCAL) {
+            p->setTransform(combined,  true /* combine */);
+        } else if (_clipFrame == ReferenceFrame::PARENT) {
+            // incoming transform is already our parent
+        } else {
+            qWarning() << "Unhandled clip type:" << static_cast<int>(_clipFrame) << "at" << property()->path();
         }
+
 #if defined(DEBUG_PAINTING)
-        p->save();
-        p->setTransform(context->globalCoordinateTransform());
         p->setPen(Qt::yellow);
         p->setBrush(QBrush(Qt::yellow, Qt::DiagCrossPattern));
         p->drawRect(_clipRect);
-        p->restore();
 #endif
-
-        QTransform t = p->transform();
-        p->setTransform(context->globalCoordinateTransform());
-        p->setClipRect(_clipRect);
         p->setClipping(true);
-        p->setTransform(t);
+        p->setClipRect(_clipRect);
+        p->setTransform(t); // restore the previous transformation
     }
 
-    QTransform combined = combinedTransform();
     p->setTransform(combined,  true /* combine */);
 
     if (!_fillColor.isValid()) {
@@ -385,7 +389,7 @@ void FGCanvasElement::markClipDirty()
     requestPolish();
 }
 
-float FGCanvasElement::parseCSSValue(QByteArray value) const
+double FGCanvasElement::parseCSSValue(QByteArray value) const
 {
     value = value.trimmed();
     // deal with %, px suffixes
@@ -396,7 +400,7 @@ float FGCanvasElement::parseCSSValue(QByteArray value) const
         value.truncate(value.length() - 2);
     }
     bool ok = false;
-    float v = value.toFloat(&ok);
+    qreal v = value.toDouble(&ok);
     if (!ok) {
         qWarning() << "failed to parse:" << value;
     }
@@ -406,7 +410,7 @@ float FGCanvasElement::parseCSSValue(QByteArray value) const
 QColor FGCanvasElement::parseColorValue(QVariant value) const
 {
     QString colorString = value.toString();
-    if (colorString.isEmpty() || colorString == "none") {
+    if (colorString.isEmpty() || (colorString == QStringLiteral("none"))) {
         return QColor(); // return an invalid color
     }
 

utils/fgqcanvas/fgcanvaselement.h

@@ -140,7 +140,7 @@ private:
     mutable ReferenceFrame _clipFrame = ReferenceFrame::GLOBAL;
 
     void parseCSSClip(QByteArray value);
-    float parseCSSValue(QByteArray value) const;
+    double parseCSSValue(QByteArray value) const;
 };
 
 using FGCanvasElementVec = std::vector<FGCanvasElement*>;

utils/fgqcanvas/fgcanvaspath.cpp

@@ -218,13 +218,13 @@ signals:
     void strokeChanged(QPen stroke);
 
 protected:
-    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
+    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override
     {
         QQuickItem::geometryChanged(newGeometry, oldGeometry);
         update();
     }
 
-    QRectF boundingRect() const
+    QRectF boundingRect() const override
     {
         if ((width() == 0.0) || (height() == 0.0)) {
             return QRectF(0.0, 0.0, implicitWidth(), implicitHeight());

utils/fgqcanvas/fgcanvastext.cpp

@@ -210,7 +210,12 @@ void FGCanvasText::dumpElement()
 void FGCanvasText::doPaint(FGCanvasPaintContext *context) const
 {
     context->painter()->setFont(_font);
-    context->painter()->setPen(fillColor());
+    QColor c = fillColor();
+    if (!c.isValid()) {
+        c = Qt::white;
+    }
+
+    context->painter()->setPen(c);
     context->painter()->setBrush(Qt::NoBrush);
     QRectF rect(0, 0, 1000, 1000);
 

utils/fgqcanvas/fgqcanvasimage.cpp

@@ -89,13 +89,13 @@ public:
     }
 
 protected:
-    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
+    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override
     {
         QQuickItem::geometryChanged(newGeometry, oldGeometry);
         update();
     }
 
-    QRectF boundingRect() const
+    QRectF boundingRect() const override
     {
         if (!widthValid() || !heightValid()) {
             return QRectF(QPointF(), m_size);