[WorldWind学习]14.ConfigurationLoader类

ConfigurationLoader主要负责WW中各个图层的加载。

首先看看安装目录Config文件夹下Earth.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<World Name="Earth" EquatorialRadius="6378137.0" LayerDirectory="Earth" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="WorldXmlDescriptor.xsd">
    <TerrainAccessor Name="SRTM">
        <TerrainTileService>
            <ServerUrl>http://worldwind25.arc.nasa.gov/wwelevation/wwelevation.aspx</ServerUrl>
            <DataSetName>srtm30pluszip</DataSetName>
            <LevelZeroTileSizeDegrees>20.0</LevelZeroTileSizeDegrees>
            <NumberLevels>12</NumberLevels>
            <SamplesPerTile>150</SamplesPerTile>
            <DataFormat>Int16</DataFormat>
            <FileExtension>bil</FileExtension>
            <CompressonType>zip</CompressonType>
        </TerrainTileService>
        <LatLonBoundingBox>
            <North>
                <Value>90.0</Value>
            </North>
            <South>
                <Value>-90.0</Value>
            </South>
            <West>
                <Value>-180.0</Value>
            </West>
            <East>
                <Value>180.0</Value>
            </East>
        </LatLonBoundingBox>
    </TerrainAccessor>
</World>

MainApplication构造函数中截取了如下代码：

foreach (FileInfo worldXmlDescriptorFile in worldXmlDescriptorFiles)
                {
                    try
                    {
                        Log.Write(Log.Levels.Debug+1, "CONF", "checking world " + worldXmlDescriptorFile.FullName + " ...");
                        World w = WorldWind.ConfigurationLoader.Load(worldXmlDescriptorFile.FullName, worldWindow.Cache);
                        if(!availableWorldList.Contains(w.Name))
                            this.availableWorldList.Add(w.Name, worldXmlDescriptorFile.FullName);

                        w.Dispose();
                        System.Windows.Forms.MenuItem mi = new System.Windows.Forms.MenuItem(w.Name, new System.EventHandler(OnWorldChange));
                        menuItemFile.MenuItems.Add(worldIndex, mi);
                        worldIndex++;
                    }
                    catch( Exception caught )
                    {
                        splashScreen.SetError( worldXmlDescriptorFile + ": " + caught.Message );
                        Log.Write(caught);
                    }
                }

                Log.Write(Log.Levels.Debug, "CONF", "loading startup world...");
                OpenStartupWorld();

首先验证世界是否存在列表中，接着就释放了w。

OpenStartupWorld()方法体最后调用了OpenWorld( curWorldFile );

/// <summary>
        /// Loads a new planet
        /// </summary>
        private void OpenWorld(string worldXmlFile)
        {
            
            if(this.worldWindow.CurrentWorld != null)
            {
                try
                {
                    this.worldWindow.ResetToolbar();
                }
                catch
                {}

                try
                {
                    foreach(PluginInfo p in this.compiler.Plugins)
                    {
                        try
                        {
                            if(p.Plugin.IsLoaded)
                                p.Plugin.Unload();
                        }
                        catch
                        {}
                    }
                }
                catch
                {}
                
                try
                {
                    this.worldWindow.CurrentWorld.Dispose();
                }
                catch
                {}
                
            }


            if(this.gotoDialog != null)
            {
                this.gotoDialog.Dispose();
                this.gotoDialog = null;
            }

            if(this.rapidFireModisManager != null)
            {
                this.rapidFireModisManager.Dispose();
                this.rapidFireModisManager = null;
            }

            if(this.animatedEarthMananger != null)
            {
                this.animatedEarthMananger.Dispose();
                this.animatedEarthMananger = null;
            }

            if(this.wmsBrowser != null)
            {
                this.wmsBrowser.Dispose();
                this.wmsBrowser = null;
            }

            //currentWorld = world;

        //    TerrainAccessor terrainAccessor = null;
        //    if(worldDescriptor.HasTerrainAccessor())
        //        terrainAccessor = this.getTerrainAccessorFromXML(worldDescriptor.TerrainAccessor);

            worldWindow.CurrentWorld = WorldWind.ConfigurationLoader.Load(worldXmlFile, worldWindow.Cache);


        /*    if(this.currentWorld.HasLayerDirectory())
            {
                string dirPath = worldDescriptor.LayerDirectory.Value;
                if(!Path.IsPathRooted(dirPath))
                    if (worldDescriptor.LayerDirectory.Value.IndexOf("//") < 0) // ?
                        dirPath = Path.Combine(  Settings.ConfigPath, dirPath );

                ArrayList nodes = new ArrayList();
                foreach (string layerSetFile in Directory.GetFiles( dirPath, "*.xml" ))
                {
                    try
                    {
                        
                        LayerSet.LayerSetDoc curLayerSetDoc = new LayerSet.LayerSetDoc();
                        LayerSet.Type_LayerSet curLayerSet = new LayerSet.Type_LayerSet(curLayerSetDoc.Load(layerSetFile));

                        RenderableObject wwroi = getRenderableObjectListFromLayerSet(this.worldWindow.CurrentWorld, curLayerSet, layerSetFile);
                        world.RenderableObjects.Add( wwroi );
                    }
                    catch (Exception caught)
                    {
                        // Altova throws System.Exception
                        splashScreen.SetError(
                            String.Format(CultureInfo.CurrentCulture, "The file '{0}' is invalid: {1}",
                            Path.GetFileName(layerSetFile), caught.Message) );
                    }
                }

                this.layerTreeNodes = (TreeNode[])nodes.ToArray(typeof(TreeNode));
            }
*/
            
            this.splashScreen.SetText("Initializing menus...");
                
            InitializePluginCompiler();

            foreach(RenderableObject worldRootObject in this.worldWindow.CurrentWorld.RenderableObjects.ChildObjects)
            {
                this.AddLayerMenuButtons(this.worldWindow, worldRootObject);
            }

            this.AddInternalPluginMenuButtons();

            this.menuItemModisHotSpots.Enabled = worldWindow.CurrentWorld.IsEarth;
            this.menuItemAnimatedEarth.Enabled = worldWindow.CurrentWorld.IsEarth;
        

        }

worldWindow.CurrentWorld = WorldWind.ConfigurationLoader.Load(worldXmlFile, worldWindow.Cache);
真正加载世界。

ConfigurationLoader的改造和使用方法：

public static World Load(string filename, Cache cache)
        {
            Log.Write(Log.Levels.Debug, "CONF", "Loading " + filename);

            // get the World Wind Settings through reflection to avoid changing the signature of Load().
            Assembly a = Assembly.GetEntryAssembly();
            Type appType = a.GetType("WorldWind.MainApplication");
            System.Reflection.FieldInfo finfo = appType.GetField("Settings", BindingFlags.Static | BindingFlags.Public | BindingFlags.GetField);
            WorldWindSettings settings = finfo.GetValue(null) as WorldWindSettings;

            XmlReaderSettings readerSettings = new XmlReaderSettings();

            if (settings.ValidateXML)
            {
                Log.Write(Log.Levels.Debug, "CONF", "validating " + filename + " against WorldXmlDescriptor.xsd and LayerSet.xsd");
                readerSettings.ValidationType = ValidationType.Schema;
                /* load the schema to validate against instead of hoping for an inline schema reference */
                XmlSchemaSet schemas = new XmlSchemaSet();
                schemas.Add(null, settings.ConfigPath + "/WorldXmlDescriptor.xsd");
                schemas.Add(null, settings.ConfigPath + "/Earth/LayerSet.xsd");


                readerSettings.Schemas = schemas;
                readerSettings.ValidationEventHandler += new ValidationEventHandler(XMLValidationCallback);
                readerSettings.ValidationFlags |= System.Xml.Schema.XmlSchemaValidationFlags.ReportValidationWarnings;
            }
            else
            {
                Log.Write(Log.Levels.Debug, "CONF", "loading " + filename + " without validation");
                readerSettings.ValidationType = ValidationType.None;
            }

            try
            {
                XmlReader docReader = XmlReader.Create(filename, readerSettings);
                XPathDocument docNav = new XPathDocument(docReader);
                XPathNavigator nav = docNav.CreateNavigator();

                XPathNodeIterator worldIter = nav.Select("/World[@Name]");
                if (worldIter.Count > 0)
                {
                    worldIter.MoveNext();
                    string worldName = worldIter.Current.GetAttribute("Name", "");
                    double equatorialRadius = ParseDouble(worldIter.Current.GetAttribute("EquatorialRadius", ""));
                    string layerDirectory = worldIter.Current.GetAttribute("LayerDirectory", "");

                    if (layerDirectory.IndexOf(":") < 0)
                    {
                        layerDirectory = Path.Combine(Path.GetDirectoryName(filename), layerDirectory);
                    }

                    TerrainAccessor[] terrainAccessor = getTerrainAccessorsFromXPathNodeIterator(worldIter.Current.Select("TerrainAccessor"),
                        System.IO.Path.Combine(cache.CacheDirectory, worldName));

                    World newWorld = new World(
                        worldName,
                        new Microsoft.DirectX.Vector3(0, 0, 0),
                        new Microsoft.DirectX.Quaternion(0, 0, 0, 0),
                        equatorialRadius,
                        cache.CacheDirectory,
                        (terrainAccessor != null ? terrainAccessor[0] : null)//TODO: Oops, World should be able to handle an array of terrainAccessors
                        );

                    //调用getRenderablesFromLayerDirectory()方法.
                    newWorld.RenderableObjects = getRenderablesFromLayerDirectory(layerDirectory, newWorld, cache);

                    return newWorld;
                }
            }
            catch (XmlSchemaException ex)
            {
                Log.Write(Log.Levels.Error, "CONF", "Exception caught during XML parsing: " + ex.Message);
                Log.Write(Log.Levels.Error, "CONF", "File " + filename + " was not read successfully.");
                // TODO: should pop up a message box or something.
                return null;
            }

            return null;
        }

getRenderablesFromLayerDirectory()方法： 

private static RenderableObjectList getRenderablesFromLayerDirectory(string layerDirectory, World parentWorld, Cache cache)
        {
            RenderableObjectList renderableCollection = new RenderableObjectList(parentWorld.Name);

            DirectoryInfo layerDir = new DirectoryInfo(layerDirectory);
            if(!layerDir.Exists)
            {
                return renderableCollection;
            }
            //从layerDirectory文件夹中读取所有的xml文件，并从xml文件中读取图层信息
            foreach(FileInfo layerFile in layerDir.GetFiles("*.xml"))
            {
                //调用getRenderableFromLayerFile()方法，从中读取RenderableObjectList 对象。
                RenderableObjectList currentRenderable = getRenderableFromLayerFile(layerFile.FullName, parentWorld, cache);
                if(currentRenderable != null)
                {
                    renderableCollection.Add(currentRenderable);
                }
            }
            //返回RenderableObjectList对象
            return renderableCollection;
        }