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 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 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(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