日常應(yīng)用中無(wú)論是草圖繪制，還是外業(yè)采集都需要在移動(dòng)端進(jìn)行空間要素的繪制。而ArcGIS Runtime SDK for Android中提供了Geometry、Feature、Graphic，這三者到底如何使用，本文稍微做做解答。

空間要素（Geometry）

Geometries用以在特定地理位置上通過形狀來(lái)表達(dá)真實(shí)世界的對(duì)象。圖層范圍、視圖范圍、GPS定位都是通過Geometries表達(dá)實(shí)現(xiàn)進(jìn)一步的數(shù)據(jù)編輯、空間分析、地理處理、位置與面積量算都離不開空間要素。

Features 與 Graphics

Feature（com.esri.arcgisruntime.data.Feature），存儲(chǔ)于Feature Table中，在 Feature Layer中進(jìn)行顯示。包含的Geometry 必須同一類型。包含的屬性信息其字段信息必須相同。用以Feature Table中進(jìn)行更新、刪除等操作。
Graphic（com.esri.arcgisruntime.mapping.view. Graphic ），存儲(chǔ)于運(yùn)行內(nèi)存中，在Graphics OverLay中進(jìn)行顯示。包含的Geometry類型可以不統(tǒng)一。通過類對(duì)象直接創(chuàng)建，僅用以繪制性顯示。

創(chuàng)建 – 矩形、點(diǎn)

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, CA
stateCapitalsPST.add(-122.891366, 47.039231); // Olympia, WA
stateCapitalsPST.add(-123.043814, 44.93326); // Salem, OR
stateCapitalsPST.add(-119.766999, 39.164885); // Carson City, NV
Multipoint multipoint = new Multipoint(stateCapitalsPST);
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創(chuàng)建 – 線、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);
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空間要素繪制 – SketchEditor

繪制類型（SketchCreationMode）

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

初始化地圖

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);
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啟動(dòng)繪制

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();
        }
    }
});
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