Add inline style selection to stylesheets

src/osgEarth/StyleSelector

@@ -35,7 +35,7 @@ namespace osgEarth
     {
     public:
         /** Constructs a style selector */
-        StyleSelector( const Config& conf =Config() );
+        StyleSelector(const Config& conf = Config());
 
         /** Constructs a style selector with a name and expression */
         StyleSelector(const std::string& name, const StringExpression& expr);
@@ -64,7 +64,7 @@ namespace osgEarth
         std::string getSelectedStyleName() const;
 
         //Configurable
-        virtual void mergeConfig( const Config& conf );
+        virtual void mergeConfig(const Config& conf);
         virtual Config getConfig() const;
 
     protected:
@@ -74,6 +74,27 @@ namespace osgEarth
         optional<Query>            _query;
     };
 
+    class OSGEARTH_EXPORT SelectorSymbol : public Symbol
+    {
+    public:
+        META_Object(osgEarth, SelectorSymbol);
+
+        SelectorSymbol(const Config& conf = {});
+        SelectorSymbol(const SelectorSymbol& rhs, const osg::CopyOp& op);
+
+        //! A predicate function (in a scripting language) that returns true if the style should be selected.
+        OE_OPTION(std::string, predicate);
+
+    public:
+        Config getConfig() const override;
+        void mergeConfig(const Config& conf) override;
+        static void parseSLD(const Config& c, class Style& style);
+
+    protected:
+
+        virtual ~SelectorSymbol() { }
+    };
+
 } // namespace osgEarth
 
 

src/osgEarth/StyleSelector.cpp

@@ -67,3 +67,44 @@ StyleSelector::getConfig() const
     conf.set( "query",      _query );
     return conf;
 }
+
+
+
+OSGEARTH_REGISTER_SIMPLE_SYMBOL(select, SelectorSymbol);
+
+SelectorSymbol::SelectorSymbol(const Config& conf) :
+    Symbol(conf)
+{
+    mergeConfig(conf);
+}
+
+SelectorSymbol::SelectorSymbol(const SelectorSymbol& rhs, const osg::CopyOp& copy) :
+    Symbol(rhs, copy),
+    _predicate(rhs._predicate)
+{
+    //nop
+}
+
+Config
+SelectorSymbol::getConfig() const
+{
+    auto conf = Symbol::getConfig();
+    conf.key() = "selector";
+    conf.set("predicate", predicate());
+    return conf;
+}
+
+void
+SelectorSymbol::mergeConfig(const Config& conf)
+{
+    conf.get("predicate", predicate());
+}
+
+void
+SelectorSymbol::parseSLD(const Config& c, Style& style)
+{
+    if (match(c.key(), "select") || match(c.key(), "select-if"))
+    {
+        style.getOrCreate<SelectorSymbol>()->predicate() = c.value();
+    }
+}

src/osgEarth/StyleSheet.cpp

@@ -35,11 +35,12 @@ StyleSheet::Options::getConfig() const
     Config conf = Layer::Options::getConfig();
 
     conf.remove("selector");
-    for (StyleSelectors::const_iterator i = selectors().begin();
-        i != selectors().end();
-        ++i)
+    for(auto& selector_pair : selectors())
     {
-        conf.add("selector", i->second.getConfig());
+        if (selector_pair.first != "__oe_auto") // do not save the auto-gen one
+        {
+            conf.add("selector", selector_pair.second.getConfig());
+        }
     }
 
     conf.remove("style");
@@ -72,10 +73,19 @@ StyleSheet::Options::getConfig() const
             scriptConf.set("language", _script->language);
         if (_script->uri.isSet())
             scriptConf.set("url", _script->uri->base());
-        //if (!_script->profile.empty())
-        //    scriptConf.set("profile", _script->profile);
         else if (!_script->code.empty())
+        {
+            auto code = _script->code;
+
+            // remove the auto-gen code
+            auto pos = code.find("// __oe_auto__");
+            if (pos != std::string::npos)
+            {
+                code = code.substr(0, pos);
+            }
+
             scriptConf.setValue(_script->code);
+        }
 
         conf.add(scriptConf);
     }
@@ -184,6 +194,51 @@ StyleSheet::Options::fromConfig(const Config& conf)
             _styles[style.getName()] = style;
         }
     }
+
+    // finally, parse each style and see if it contains a "select" symbol. 
+    // if so, automatically add a selector and a script to support each one.
+    StyleSelector* auto_selector = nullptr;
+    std::stringstream auto_script;
+
+    for (auto& style_entry : _styles)
+    {
+        auto& style = style_entry.second;
+        auto* selector_symbol = style.get<SelectorSymbol>();
+        if (selector_symbol)
+        {
+            if (!auto_selector)
+            {
+                auto_selector = new StyleSelector();
+                auto_selector->name() = "__oe_auto";
+                auto_selector->styleExpression() = StringExpression("__oe_select_style()");
+                _selectors[auto_selector->name().get()] = *auto_selector;
+
+                auto_script << "// __oe_auto__\n";
+                auto_script << "function __oe_select_style() {\n";
+            }
+
+            auto_script << "    if (" << selector_symbol->predicate().get() << ") return \"" << style.getName() << "\";\n";
+        }
+    }
+
+    if (auto_selector)
+    {
+        auto_script << "    return 'default';\n}\n";
+        auto new_code = auto_script.str();
+
+        if (!_script)
+        {
+            _script = new ScriptDef();
+            _script->language = "javascript";
+            _script->code = new_code;
+        }
+        else
+        {
+            _script->code = _script->code + "\n\n" + new_code;
+        }
+
+        //OE_INFO << LC << "Generated script:\n" << new_code << std::endl;
+    }
 }
 
 //...................................................................

tests/feature_select_symbol.earth

@@ -0,0 +1,63 @@
+<!--
+osgEarth Sample
+Demonstrates how to select a style name using javascript.
+-->
+
+<map name="Demo: style selectors">
+
+    <options>
+        <terrain color="#004d8f"/>
+    </options>
+
+    <OGRFeatures name="country-data">
+        <url>../data/world.shp</url>
+        <filters>
+            <buffer distance="-0.05"/>
+        </filters>
+    </OGRFeatures>
+
+    <FeatureModel name="countries" features="country-data" pickable="true">        
+        <styles>        
+            <style type="text/css">
+                base { 
+                    altitude-clamping: terrain-drape;
+                    render-backface-culling: false;
+                }
+
+                p1 : base { 
+                    select: between(feature.properties.pop, 0, 14045470);
+                    fill: #ff3f3f;
+                }
+
+                p2 : base {
+                    select: between(feature.properties.pop, 14045470, 43410900);
+                    fill: #3fff3f;
+                }
+
+                p3 : base {
+                    select: between(feature.properties.pop, 43410900, 97228750);
+                    fill: #ff8f00;
+                }
+
+                p4 : base {
+                    select: between(feature.properties.pop, 97228750, 258833000);
+                    fill: #ff3fff;
+                }
+
+                default : base {
+                    fill: #ffff3f;
+                }
+            </style>
+
+            <script language="javascript">
+              <![CDATA[
+                function between(val_as_string, low, high) {
+                    var v = parseFloat(val_as_string);
+                    return low <= v && v < high;
+                }
+              ]]>
+            </script>
+        </styles>        
+    </FeatureModel>
+
+</map>