ArcGIS for Android 离线数据图例加载

  图例是地图展示里常用的辅助展示工具。曾经我采用过将图例截成图片转为2进制保存到数据库里，然后在加载图层时候调取对应图片作为图例展示。但是后来知道geodatabase数据其实就是个空间数据库，如果是通过geodatabase数据加载图层，图斑都是geodatabase数据里的空间数据Geometry根据样式Symbol进行动态渲染，所以这个Symbol如果能提取出来，也就是我们要的图例了。根据这个思路，我找了找，果然找到了对应的方法，于是记录下来。

  首先我们还是先初始化地图，并且加载图层：

mMapView=(MapView)findViewById(R.id.mapview);
rvDownload=(RecyclerView)findViewById(R.id.rv_tuli);
String path=StorageUtil.getSDCardRootPath(getApplicationContext())+"/ydyzt/data/GD_TDYT.geodatabase";
Geodatabase localGdb=null;
try {
localGdb = new Geodatabase(path);
}catch (Exception e){
e.printStackTrace();
}
if (localGdb != null) {
for (GeodatabaseFeatureTable gdbFeatureTable : localGdb.getGeodatabaseTables()) {
if (gdbFeatureTable.hasGeometry()){
FeatureLayer layer = new FeatureLayer(gdbFeatureTable);
mMapView.addLayer(layer);
}
}
}
mMapView.setMapBackground(0xFAFAFA, 0xffffff, 0.0f, 0.0f);//地图背景

  然后根据我们加载的图层获取对应的符号，然后将符号按照点，线，面类型转换成对应的Bitmap，而图例名称则取GeodatabaseFeatureTable里对应FeatureTemplate的名称，就构成了我们的图例：

Layer layer=mMapView.getLayer(0);
tuliBeanList=new ArrayList<>();
if(layer instanceof FeatureLayer){
String typeFileid= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).getTypeIdField();
if(typeFileid.equalsIgnoreCase("")){//TypeIdField没有值
//获取图层中的FeatureTemplate
List<FeatureTemplate> templates= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).getFeatureTemplates();
//从templates构造出图例
for(FeatureTemplate template :templates){
try {
//根据FeatureTemplate生成GdbFeature
GeodatabaseFeature feature= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).createFeatureWithTemplate(template, null);
Renderer renderer = ((FeatureLayer) layer).getRenderer();
//获取符号
Symbol symbol =  renderer.getSymbol(feature);
//得到代表图例的图片
Bitmap bitmap=createBitmapFromSymbol(symbol,layer);
String name=template.getName();
TuliBean bean=new TuliBean(name,bitmap);
tuliBeanList.add(bean);
//设置图例的布局和点击事件
// populateTemplateView(layerTemplate,bitmap,template,symbol,(FeatureLayer)layer);
} catch (Exception e) {
e.printStackTrace();
}
}
initTuli();
}else{//TypeIdField有值
List<FeatureType> featureTypes= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).getFeatureTypes();
for(FeatureType featureType :featureTypes){
FeatureTemplate[] templates= featureType.getTemplates();
for(FeatureTemplate template :templates){
try {
//根据FeatureTemplate生成GeodatabaseFeature
GeodatabaseFeature feature= ((GeodatabaseFeatureTable)(((FeatureLayer)layer).getFeatureTable())).createFeatureWithTemplate(template, null);
Renderer renderer = ((FeatureLayer) layer).getRenderer();
//获取符号
Symbol symbol =  renderer.getSymbol(feature);
//得到代表图例的图片
Bitmap bitmap=createBitmapFromSymbol(symbol,layer);
String name=template.getName();
TuliBean bean=new TuliBean(name,bitmap);
tuliBeanList.add(bean);
//设置图例的布局和点击事件
//populateTemplateView(layerTemplate,bitmap,template,symbol,(FeatureLayer)layer);
} catch (Exception e) {
e.printStackTrace();
}
}
initTuli();
}
}
}

  符号转换Bitmap的方法为：

//根据Symbol和Layer来创建相对应的图例
private Bitmap createBitmapFromSymbol(Symbol symbol,Layer layer) {
Bitmap bitmap=null;
Geometry.Type type= ((FeatureLayer)layer).getGeometryType();
//跟不同的Type来创建不同的图例
if(type.equals(Geometry.Type.POINT)){//点图层
Point point=new Point(20, 20);
bitmap= SymbolHelper.getLegendImage(symbol, point, 50, 50, Color.WHITE);
}else if(type.equals(Geometry.Type.POLYLINE)){//线图层
Polyline polyLine=new Polyline();
polyLine.startPath(0,0);
polyLine.lineTo(40,40);
bitmap=SymbolHelper.getLegendImage(symbol, polyLine, 50, 50, Color.WHITE);
}else if(type.equals(Geometry.Type.POLYGON)){//面图层
Polygon polygon=new Polygon();
polygon.startPath(0, 0);
polygon.lineTo(250, 0);
polygon.lineTo(250, 100);
polygon.lineTo(0, 100);
polygon.lineTo(0, 0);
bitmap= SymbolHelper.getLegendImage(symbol, polygon, 250, 100, Color.WHITE);
}
return bitmap;
}

  最后将获取到的图例展示出来：

baseRecyclerAdapterOfflineData=new BaseRecyclerAdapter<TuliBean>(this,tuliBeanList) {
@Override
public int getItemLayoutId(int viewType) {
return R.layout.item_tuli;
}

@Override
public void bindData(RecyclerViewHolder holder, int position, TuliBean item) {

TextView tvName=holder.getTextView(R.id.tv_tuliname);
ImageView ivTuli=holder.getImageView(R.id.iv_tuli);
tvName.setText(item.getTuliName());
ivTuli.setImageBitmap(item.getBitmap());
}
};
rvDownload.setAdapter(baseRecyclerAdapterOfflineData);
rvDownload.setLayoutManager(new LinearLayoutManager(this));
rvDownload.setItemAnimator(new DefaultItemAnimator());

  看看最后的效果：



demo下载地址：http://download.csdn.net/detail/bit_kaki/9926236

参考文章：http://blog.csdn.net/yifei1989/article/details/17339095