安卓智能地图开发与实施十八：空间要素绘制

空间要素绘制

日常应用中无论是草图绘制，还是外业采集都需要在移动端进行空间要素的绘制。而ArcGIS Runtime SDK for Android中提供了Geometry、Feature、Graphic，这三者到底如何使用，本文稍微做做解答。

空间要素（Geometry）

Geometries用以在特定地理位置上通过形状来表达真实世界的对象。图层范围、视图范围、GPS定位都是通过Geometries表达实现进一步的数据编辑、空间分析、地理处理、位置与面积量算都离不开空间要素。

Features 与 Graphics

Feature（com.esri.arcgisruntime.data.Feature），存储于Feature Table中，在 Feature Layer中进行显示。包含的Geometry 必须同一类型。包含的属性信息其字段信息必须相同。用以Feature Table中进行更新、删除等操作。
Graphic（com.esri.arcgisruntime.mapping.view. Graphic ），存储于运行内存中，在Graphics OverLay中进行显示。包含的Geometry类型可以不统一。通过类对象直接创建，仅用以绘制性显示。

创建 – 矩形、点

Envelope envelope = new Envelope(-123.0, 33.5, -101.0, 48.0, SpatialReferences.getWgs84());Point pt = new Point(34.056295, -117.195800, SpatialReferences.getWgs84());PointCollection stateCapitalsPST = new PointCollection(SpatialReferences.getWgs84());stateCapitalsPST.add(-121.491014, 38.579065); // Sacramento, CAstateCapitalsPST.add(-122.891366, 47.039231); // Olympia, WAstateCapitalsPST.add(-123.043814, 44.93326); // Salem, ORstateCapitalsPST.add(-119.766999, 39.164885); // Carson City, NVMultipoint multipoint = new Multipoint(stateCapitalsPST);

创建 – 线、面

PointCollection borderCAtoNV = new PointCollection(SpatialReferences.getWgs84());borderCAtoNV.add(-119.992, 41.989);borderCAtoNV.add(-119.994, 38.994);borderCAtoNV.add(-114.620, 35.0);Polyline polyline = new Polyline(borderCAtoNV);PointCollection coloradoCorners = new PointCollection(SpatialReferences.getWgs84());    coloradoCorners.add(-109.048, 40.998);    coloradoCorners.add(-102.047, 40.998);    coloradoCorners.add(-102.037, 36.989);    coloradoCorners.add(-109.048, 36.998);    Polygon polygon = new Polygon(coloradoCorners);

空间要素绘制 – SketchEditor

绘制类型（SketchCreationMode）

• POINT
• MULTIPOINT
• POLYLINE
• POLYGON
• FREEHAND_LINE
• FREEHAND_POLYGON

初始化地图

mainMapView = (MapView) findViewById(R.id.mainMapView);mainBasemap = new Basemap(        TianDiTuMethodsClass.CreateTianDiTuTiledLayer(                TianDiTuMethodsClass.LayerType.TIANDITU_VECTOR_2000));mainBasemap.getBaseLayers().add(        TianDiTuMethodsClass.CreateTianDiTuTiledLayer(                TianDiTuMethodsClass.LayerType.TIANDITU_VECTOR_ANNOTATION_CHINESE_2000));mainArcGISMap = new ArcGISMap(mainBasemap);mainMapView.setMap(mainArcGISMap);mainSketchEditor = new SketchEditor();mainSketchStyle = new SketchStyle();mainSketchEditor.setSketchStyle(mainSketchStyle);mainMapView.setSketchEditor(mainSketchEditor);

启动绘制

mPointButton = (ImageButton) findViewById(R.id.pointSketchButton);mPointButton.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View view) {        try {            //mainSketchEditor.stop();            mainSketchEditor.start(SketchCreationMode.POINT);        }        catch (Exception e)        {            e.getCause();        }    }});mPolylineButton = (ImageButton) findViewById(R.id.polylineSketchButton);mPolylineButton.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View view) {        try {            //mainSketchEditor.stop();            mainSketchEditor.start(SketchCreationMode.POLYLINE);        }        catch (Exception e)        {            e.getCause();        }    }});mPolygonButton = (ImageButton) findViewById(R.id.polygonSketchButton);mPolygonButton.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View view) {        try {            //mainSketchEditor.stop();            mainSketchEditor.start(SketchCreationMode.POLYGON);        }        catch (Exception e)        {            e.getCause();        }    }});mPolylineFreeheadButton = (ImageButton) findViewById(R.id.polylineFreeheadSketchButton);mPolylineFreeheadButton.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View view) {        try {            //mainSketchEditor.stop();            mainSketchEditor.start(SketchCreationMode.FREEHAND_LINE);        }        catch (Exception e)        {            e.getCause();        }    }});mPolygonFreeheadButton = (ImageButton) findViewById(R.id.polygonFreeheadSketchButton);mPolygonFreeheadButton.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View view) {        try {            //mainSketchEditor.stop();            mainSketchEditor.start(SketchCreationMode.FREEHAND_POLYGON);        }        catch (Exception e)        {            e.getCause();        }    }});

结尾

源程序请自行下载（注：已包含hymn-release.aar）：
链接：http://pan.baidu.com/s/1qYlYX68 密码：b4bk
若失效，可发邮件给韩源萌（[e-mail]）索要。