C# 调用 Google Earth Com API开发（四）

本篇继续介绍Google Earth COM API开发的基础知识，相对第三篇的改进如下：

1)增加鼠标滚轮支持，可以实现放大、缩小。此功能利用上一篇提供的HookAPI.dll实现

2)读取PlaceMarks（Google Earth界面中的位置）并显示、隐藏

3)读取所有图层，显示并隐藏

下面，继续放代码：

1、鼠标滚轮事件，实现放大、缩小

...
// 放大
private const long ZoomIn = 0x00780000;
// 缩小
private const long ZoomOut = 0xFF880000;
...
mouseHook.MouseWheel += new MouseEventHandler(mouseHook_MouseWheel);
...
/// <summary>
/// 鼠标钩子。鼠标滚动事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void mouseHook_MouseWheel(object sender, MouseEventArgs e)
{
    IntPtr hWnd = NativeMethods.WindowFromPoint(e.Location);
    if (hWnd == this.GeRenderHWnd)
    {
        Point point = this.Control.PointToClient(e.Location);
        // 如果鼠标位置在控件内部，则说明鼠标在GoogleEarth视图范围内进行了滚动
        if (this.Control.ClientRectangle.Contains(point))
        {
            NativeMethods.PostMessage(GeRenderHWnd, (int)WM_MOUSE.WM_MOUSEWHEEL, e.Delta == 120 ? ZoomIn : ZoomOut, 0);
        }
    }
}

2、读取PlaceMarks

Google Earth COM API中提供了两个读取PlaceMarks的函数。一个是GetTemporaryPlaces()，用来读取临时位置；另一个是GetMyPlaces()，用来读取自定义位置，即GoogleEarth中显示的“我的位置”。呵呵

...
/// <summary>
/// 显示位置“PlaceMarks”。位置分为两种，一种时TemporaryPlaces，另一种为MyPlaces
/// </summary>
protected void ShowPlaces()
{
    Thread.Sleep(500);
    // 获取MyPlaces
    FeatureGE myPlace = GeApp.GetMyPlaces();
    // 获取临时位置
    FeatureGE temporaryPlace = GeApp.GetTemporaryPlaces();
    // 
    List<FeatureGE> places = new List<FeatureGE>();
    places.Add(myPlace);
    places.Add(temporaryPlace);
  
    // 获取工具面板
    GEToolPad toolPad = GetToolPad();
    // 显示所有位置
    toolPad.ShowPlaces(places);
}
...
/// <summary>
/// 显示所有PlaceMarks（位置）
/// </summary>
/// <param name="places"></param>
public void ShowPlaces(List<FeatureGE> places)
{
    if (this.InvokeRequired)
    {
        Action method = delegate {
            InternalShowPlaces(places);
        };
  
        try
        {
            this.Invoke(method);
        }
        catch { }
    }
    else
    {
        InternalShowPlaces(places);
    }
}
/// <summary>
/// 显示所有PlaceMarks（位置）。被ShowPlaces函数调用
/// </summary>
/// <param name="places"></param>
protected void InternalShowPlaces(List<FeatureGE> places)
{
    this.tvPlaces.Nodes.Clear();
  
    if (places == null || places.Count <= 0)
        return;
  
    foreach (FeatureGE place in places)
    {
        TreeNode node = new TreeNode(place.Name);
        node.Checked = place.Visibility > 0;
        node.Tag = place;
  
        ShowChildrenPlaces(place, node);
  
        node.Expand();
  
        this.tvPlaces.Nodes.Add(node);
    }
}
/// <summary>
/// 显示指定PlaceMark的子PlaceMark
/// </summary>
/// <param name="place">父PlaceMark</param>
/// <param name="node">父节点</param>
protected void ShowChildrenPlaces(FeatureGE place, TreeNode node)
{
    FeatureCollectionGE places = place.GetChildren();
  
    foreach (FeatureGE child in places)
    {
        TreeNode tn = new TreeNode(child.Name);
        tn.Checked = child.Visibility > 0;
        tn.Tag = child;
  
        ShowChildrenPlaces(child, tn);
  
        node.Nodes.Add(tn);
    }
}

3、读取图层

...
/// <summary>
/// 显示图层
/// </summary>
protected void ShowLayers()
{
    Thread.Sleep(500);
    // 获取所有图层信息
    FeatureCollectionGE layers = GeApp.GetLayersDatabases();
    // 获取工具面板
    GEToolPad toolPad = GetToolPad();
    // 显示所有图层
    toolPad.ShowLayers(layers);
}
...
/// <summary>
/// 将给定的图层集合显示在“图层”选项卡的树形控件中
/// </summary>
/// <param name="layers">图层集合</param>
public void ShowLayers(FeatureCollectionGE layers)
{
    if (this.InvokeRequired)
    {
        Action method = delegate {
            InternalShowLayers(layers);
        };
        try
        {
            this.Invoke(method);
        }
        catch { }
    }
    else
    {
        InternalShowLayers(layers);
    }
}
/// <summary>
/// 将给定的图层集合显示在“图层”选项卡的树形控件中.被公共函数ShowLayers调用
/// </summary>
/// <param name="layers"></param>
protected void InternalShowLayers(FeatureCollectionGE layers)
{
    this.tvLayers.Nodes.Clear();
  
    if (layers == null || layers.Count <= 0)
    {
        return;
    }
  
    foreach (FeatureGE layer in layers)
    {
        TreeNode node = new TreeNode(layer.Name);
        node.Checked = layer.Visibility > 0;
        node.Tag = layer;
  
        ShowChidrenLayers(layer, node);
  
        node.Expand();
  
        this.tvLayers.Nodes.Add(node);
    }
}
/// <summary>
/// 显示指定图层的子图层
/// </summary>
/// <param name="layer">当前图层</param>
/// <param name="node">当前节点</param>
protected void ShowChidrenLayers(FeatureGE layer, TreeNode node)
{
    FeatureCollectionGE layers = layer.GetChildren();
  
    foreach (FeatureGE child in layers)
    {
        TreeNode tn = new TreeNode(child.Name);
        tn.Checked = child.Visibility > 0;
        tn.Tag = child;
  
        ShowChidrenLayers(child, tn);
  
        node.Nodes.Add(tn);
    }
}

呵呵，代码很简单。按照此代码修改第三篇的源程序就可以实现本篇的功能了。

GoogleEarthDemo

posted @ 2009-05-25 21:16 温伟鹏阅读(10900) 评论(36) 编辑收藏举报

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