Canvas: fix property inheritance.

- Do not override style of children if they have own values set.
 - Retrieve style of parent if own style value has been removed.

simgear/canvas/elements/CanvasElement.cxx

@@ -21,6 +21,7 @@
 #include <simgear/canvas/CanvasEventListener.hxx>
 #include <simgear/canvas/CanvasEventVisitor.hxx>
 #include <simgear/canvas/MouseEvent.hxx>
+#include <simgear/misc/strutils.hxx>
 #include <simgear/scene/material/parseBlendFunc.hxx>
 
 #include <osg/Drawable>
@@ -315,7 +316,9 @@ namespace canvas
   //----------------------------------------------------------------------------
   void Element::childRemoved(SGPropertyNode* parent, SGPropertyNode* child)
   {
-    if( parent == _node && child->getNameString() == NAME_TRANSFORM )
+    if( parent == _node )
+    {
+      if( child->getNameString() == NAME_TRANSFORM )
       {
         if( !_transform.valid() )
           return;
@@ -339,6 +342,13 @@ namespace canvas
         _transform_dirty = true;
         return;
       }
+      else if( StyleSetter const* setter =
+                 getStyleSetter(child->getNameString()) )
+      {
+        setStyle(getParentStyle(child), setter);
+        return;
+      }
+    }
 
     childRemoved(child);
   }
@@ -350,8 +360,17 @@ namespace canvas
     if( parent == _node )
     {
       const std::string& name = child->getNameString();
-      if( setStyle(child) )
+      if( StyleSetter const* setter = getStyleSetter(name) )
+      {
+        SGPropertyNode const* style = child;
+        if( isStyleEmpty(child) )
+        {
+          child->clearValue();
+          style = getParentStyle(child);
+        }
+        setStyle(style, setter);
         return;
+      }
       else if( name == "update" )
         return update(0);
       else if( name == "visible" )
@@ -371,21 +390,10 @@ namespace canvas
   }
 
   //----------------------------------------------------------------------------
-  bool Element::setStyle(const SGPropertyNode* child)
+  bool Element::setStyle( const SGPropertyNode* child,
+                          const StyleSetter* setter )
   {
-    StyleSetters::const_iterator setter =
-      _style_setters.find(child->getNameString());
-    if( setter == _style_setters.end() )
-      return false;
-
-    const StyleSetter* style_setter = &setter->second.setter;
-    while( style_setter )
-    {
-      if( style_setter->func(*this, child) )
-        return true;
-      style_setter = style_setter->next;
-    }
-    return false;
+    return canApplyStyle(child) && setStyleImpl(child, setter);
   }
 
   //----------------------------------------------------------------------------
@@ -516,6 +524,67 @@ namespace canvas
     }
   }
 
+  //----------------------------------------------------------------------------
+  bool Element::isStyleEmpty(const SGPropertyNode* child) const
+  {
+    return !child
+        || simgear::strutils::strip(child->getStringValue()).empty();
+  }
+
+  //----------------------------------------------------------------------------
+  bool Element::canApplyStyle(const SGPropertyNode* child) const
+  {
+    if( _node == child->getParent() )
+      return true;
+
+    // Parent values do not override if element has own value
+    return isStyleEmpty( _node->getChild(child->getName()) );
+  }
+
+  //----------------------------------------------------------------------------
+  bool Element::setStyleImpl( const SGPropertyNode* child,
+                              const StyleSetter* setter )
+  {
+    const StyleSetter* style_setter = setter
+                                    ? setter
+                                    : getStyleSetter(child->getNameString());
+    while( style_setter )
+    {
+      if( style_setter->func(*this, child) )
+        return true;
+      style_setter = style_setter->next;
+    }
+    return false;
+  }
+
+  //----------------------------------------------------------------------------
+  const Element::StyleSetter*
+  Element::getStyleSetter(const std::string& name) const
+  {
+    StyleSetters::const_iterator setter = _style_setters.find(name);
+    if( setter == _style_setters.end() )
+      return 0;
+
+    return &setter->second.setter;
+  }
+
+  //----------------------------------------------------------------------------
+  const SGPropertyNode*
+  Element::getParentStyle(const SGPropertyNode* child) const
+  {
+    // Try to get value from parent...
+    if( _parent )
+    {
+      Style::const_iterator style =
+        _parent->_style.find(child->getNameString());
+      if( style != _parent->_style.end() )
+        return style->second;
+    }
+
+    // ...or reset to default if none is available
+    return child; // TODO somehow get default value for each style?
+  }
+
   //----------------------------------------------------------------------------
   void Element::setDrawable( osg::Drawable* drawable )
   {

simgear/canvas/elements/CanvasElement.hxx

@@ -117,7 +117,8 @@ namespace canvas
                                  SGPropertyNode * child );
       virtual void valueChanged(SGPropertyNode * child);
 
-      virtual bool setStyle(const SGPropertyNode* child);
+      virtual bool setStyle( const SGPropertyNode* child,
+                             const StyleSetter* setter = 0 );
 
       /**
        * Set clipping shape
@@ -441,6 +442,14 @@ namespace canvas
         );
       }
 
+      bool isStyleEmpty(const SGPropertyNode* child) const;
+      bool canApplyStyle(const SGPropertyNode* child) const;
+      bool setStyleImpl( const SGPropertyNode* child,
+                         const StyleSetter* setter = 0 );
+
+      const StyleSetter* getStyleSetter(const std::string& name) const;
+      const SGPropertyNode* getParentStyle(const SGPropertyNode* child) const;
+
       virtual void childAdded(SGPropertyNode * child)  {}
       virtual void childRemoved(SGPropertyNode * child){}
       virtual void childChanged(SGPropertyNode * child){}

simgear/canvas/elements/CanvasGroup.cxx

@@ -174,20 +174,20 @@ namespace canvas
   }
 
   //----------------------------------------------------------------------------
-  bool Group::setStyle(const SGPropertyNode* style)
+  bool Group::setStyle( const SGPropertyNode* style,
+                        const StyleSetter* setter )
   {
-    // Don't propagate styles directly applicable to this group
-    if( Element::setStyle(style) )
-      return true;
-
-    if(    style->getParent() != _node
-        && _style.find(style->getNameString()) != _style.end() )
+    if( !canApplyStyle(style) )
       return false;
 
+    // Don't propagate styles directly applicable to this group
+    if( setStyleImpl(style, setter) )
+      return true;
+
     bool handled = false;
     for(size_t i = 0; i < _transform->getNumChildren(); ++i)
     {
-      if( getChildByIndex(i)->setStyle(style) )
+      if( getChildByIndex(i)->setStyle(style, setter) )
         handled = true;
     }
 

simgear/canvas/elements/CanvasGroup.hxx

@@ -92,7 +92,8 @@ namespace canvas
 
       virtual bool traverse(EventVisitor& visitor);
 
-      virtual bool setStyle(const SGPropertyNode* child);
+      virtual bool setStyle( const SGPropertyNode* child,
+                             const StyleSetter* setter = 0 );
 
       virtual osg::BoundingBox getTransformedBounds(const osg::Matrix& m) const;
 

simgear/canvas/elements/CanvasImage.cxx

@@ -400,8 +400,9 @@ namespace canvas
   //----------------------------------------------------------------------------
   void Image::setFill(const std::string& fill)
   {
-    osg::Vec4 color;
-    if( !parseColor(fill, color) )
+    osg::Vec4 color(1,1,1,1);
+    if(    !fill.empty() // If no color is given default to white
+        && !parseColor(fill, color) )
       return;
 
     _colors->front() = color;

simgear/canvas/elements/CanvasPath.cxx

@@ -110,7 +110,7 @@ namespace canvas
        */
       void setFill(const std::string& fill)
       {
-        if( fill == "none" )
+        if( fill.empty() || fill == "none" )
         {
           _mode &= ~VG_FILL_PATH;
         }
@@ -150,7 +150,7 @@ namespace canvas
        */
       void setStroke(const std::string& stroke)
       {
-        if( stroke == "none" )
+        if( stroke.empty() || stroke == "none" )
         {
           _mode &= ~VG_STROKE_PATH;
         }