动态加载影像图层为例
研究了两三天算是弄出来了。本例适合影像数据量特别的大程序使用，可以动态的添加删除影像数据，还有不完善的地方，不过基本满足要求。
1.首先得到关键点的图层
m_Map = axMapControl.Map;
int l = 0;
int f = 0;
for (int j = 0; j < m_Map.LayerCount; j++)
{
if (m_Map.get_Layer(j).Name == "Points")
{
l = j;//获得Points图层
}
}
2.取得该范围
double xmax = env.XMax;
double ymax = env.YMax;
double xmin = env.XMin;
double ymin = env.YMin;
3.经纬度以及名称字段的属性信息存入arraylist
ArrayList aList = new ArrayList();
ArrayList bList = new ArrayList();
ArrayList nList = new ArrayList();
IFeatureLayer ilayer = (IFeatureLayer)m_Map.get_Layer(l);//得到点图层
IFeatureCursor pFeatureCursor;
pFeatureCursor = ilayer.FeatureClass.Search(null, false);
IFeature pFeature;
pFeature = pFeatureCursor.NextFeature();
while (pFeature != null)
{
string jdValue = Convert.ToString(pFeature.get_Value(4));
string wdValue = Convert.ToString(pFeature.get_Value(5));
string name = Convert.ToString(pFeature.get_Value(2));
pFeature = pFeatureCursor.NextFeature();
aList.Add(jdValue);//经纬度以及name存入arraylist
bList.Add(wdValue);
nList.Add(name);
}
4.遍历arraylist并判断点是否在可视范围内
if (m_Map.MapScale < 400000)
{
for (int j = 0; j < 35; j++)
{
double jd = double.Parse(aList[j].ToString());
double wd = double.Parse(bList[j].ToString());
//判断土层中是否已经存在某个影像数据，若存在则不进行坐标的判断
if (jd >= xmin && jd <= xmax)
{
if (wd >= ymin && wd <= ymax)
{ nameid = nList[j].ToString();//获得name属性
for (int q = 0; q < axMapControl.Map.LayerCount; q++)
{
temp = getname == nameid + ".tif";
getname = Convert.ToString(axMapControl.get_Layer(q).Name);
if(temp)
indexa = q - 1;
}
5.调用添加影像数据函数dynamicadd()（目前是本地）
//动态加载删格数据
public void dynamicadd(string strFullPath)
{
int Index = strFullPath.LastIndexOf("\");
string fileName = strFullPath.Substring(Index + 1);
string filePath = strFullPath.Substring(0, Index);
IWorkspaceFactory workspaceFactory = new RasterWorkspaceFactory();
IRasterWorkspace rasterWorkspace = (IRasterWorkspace)workspaceFactory.OpenFromFile(filePath, 0);
IRasterDataset rasterDataset = (IRasterDataset)rasterWorkspace.OpenRasterDataset(fileName);
IRasterLayer rasterLayer = new RasterLayerClass();
rasterLayer.CreateFromDataset(rasterDataset);
axMapControl.AddLayer(rasterLayer, 2);//有心的话你会发现此函数与axMapControl.Map.AddLayer()的区别（没有插入的图层序号），可以试试哦！
}
6.判断是否已经动态加载
if (temp)
{
//MessageBox.Show(Convert.ToString(axMapControl.get_Layer(indexa).Name));//测试
axMapControl.get_Layer(indexa).MinimumScale = 250000;//设定这个图层的可见范围？
return;
}
else
{
string strFullPath = "";
strFullPath = Application.StartupPath + @"\data影像" + nameid + ".tif";//这里就是影像图层的路径
dynamicadd(strFullPath);
axMapControl.get_Layer(2).MinimumScale = 250000;
break;
}
7将影像图层控制在五个以内超过了就删除
clearLayer.Add(nameid);
axMapControl.get_Layer(2).MinimumScale = 250000;
if (clearLayer.Count > 5)//当图层超过5个时清除最早加载的图层（应该是不在视图范围内的）
{
for (int e = 0; e < axMapControl.LayerCount;e++ )
{
if(axMapControl.get_Layer(e).Name.ToString() == clearLayer[0].ToString()+".tif")
{
//ILayer layer = null;
//layer = axMapControl.Map.get_Layer(e);
axMapControl.DeleteLayer(e);
}
}
8.综上所述
调用部分
//范围
IEnvelope env = axMapControl.Extent;//获取范围
fanwei(env);//可以返回string nameid再根据nameid寻找路径
主要声明的字段以及arraylist
string nameid = "";//关键的传值字段，连接影像数据的路径
string getname = "";//
bool temp =false;//判断是否已经加载的bool类型变量
ArrayList clearLayer = new ArrayList();
主要函数部分
public void fanwei(IEnvelope env)
{
m_Map = axMapControl.Map;
int l = 0;
int f = 0;
for (int j = 0; j < m_Map.LayerCount; j++)
{
if (m_Map.get_Layer(j).Name == "Points")
{
l = j;//获得Points图层为以后得到图层传递l
}
}
double xmax = env.XMax;
double ymax = env.YMax;
double xmin = env.XMin;
double ymin = env.YMin;//屏幕范围参数取值
ArrayList aList = new ArrayList();
ArrayList bList = new ArrayList();
ArrayList nList = new ArrayList();//用来存储经纬度以及名称字段的arraylist
IFeatureLayer ilayer = (IFeatureLayer)m_Map.get_Layer(l);//得到点图层
IFeatureCursor pFeatureCursor;
pFeatureCursor = ilayer.FeatureClass.Search(null, false);
IFeature pFeature;
pFeature = pFeatureCursor.NextFeature();//用来获取字段值的关键
while (pFeature != null)
{
string jdValue = Convert.ToString(pFeature.get_Value(4));
string wdValue = Convert.ToString(pFeature.get_Value(5));
string name = Convert.ToString(pFeature.get_Value(2));
pFeature = pFeatureCursor.NextFeature();
aList.Add(jdValue);//经纬度以及name存入arraylist
bList.Add(wdValue);
nList.Add(name);
}
if (m_Map.MapScale < 400000)//比例尺大于此值将进行判断
{
for (int j = 0; j < 35; j++)//在这里我知道共有35个点
{
double jd = double.Parse(aList[j].ToString());
double wd = double.Parse(bList[j].ToString());
//判断点是否在可视范围内，在范围内则取值nameid与影像数据路径相关联
//判断图层中是否已经存在某个影像数据，若存在则不进行坐标的判断
if (jd >= xmin && jd <= xmax)
{
if (wd >= ymin && wd <= ymax)
{
nameid = nList[j].ToString();//获得name属性
for (int q = 0; q < axMapControl.Map.LayerCount; q++)
{
temp = (getname == nameid + ".tif");
getname = Convert.ToString(axMapControl.get_Layer(q).Name);
if(temp)
{
indexa = q - 1;
break;//很重要！！！！
}
}
if (temp)
{
for (int e = 0; e < axMapControl.LayerCount; e++)
{
for (int r = 0; r < clearLayer.Count; r++)
{
if (axMapControl.get_Layer(e).Name.ToString() == clearLayer[r].ToString() + ".tif")
{
//ILayer layer = null;
//layer = axMapControl.Map.get_Layer(e);
axMapControl.get_Layer(e).MinimumScale = 250000;
}
}
}
return;//return还是break要注意
}
else
{
string strFullPath = "";
strFullPath = Application.StartupPath + @"\data影像" + nameid + ".tif";
dynamicadd(strFullPath);
clearLayer.Add(nameid);
if (clearLayer.Count > 5)//当图层超过5个时清除最早加载的图层（应该是不在视图范围内的）
{
for (int e = 0; e < axMapControl.LayerCount;e++ )
{
if(axMapControl.get_Layer(e).Name.ToString() == clearLayer[0].ToString()+".tif")
{
//ILayer layer = null;
//layer = axMapControl.Map.get_Layer(e);
axMapControl.DeleteLayer(e);
}
}
}
break;
} }
}
}
}
}
如果有问题欢迎提出建议！刚刚做出来可能有需要完善的地方