topic Re: GraphicsLayer removeall graphics come back after zoom in ArcGIS JavaScript Maps SDK Questions

GraphicsLayer removeall graphics come back after zoom

XueGao2 — Sun, 12 Dec 2021 03:29:33 GMT

I'm using JavaScript API 4.5 and my application is using webmap. I want to highlight the feature that the user clicks on (polygon) and clear the current one and highlight the new one every time the user clicks on a new feature.

I created a GraphicsLayer for it and use removeall() to remove all the graphics before draw the new one. This works fine until I zoom the map. When I zoom the map all the graphics come back and I can't figure out where they are stored. I checked the graphics layer and there is always one graphic in it which is the most recent selected feature.

highlightFeature(graphic) {
 let theComponent = this;
 let graphicsLayerMap;

 theComponent.mapService.webMaps[theComponent.mapService.currentMap].layers.items.forEach(function(layer){
  if (layer.type === 'graphics') {
    graphicsLayerMap = layer;
  }
 });
 // SimpleFillSymbolProperties only necessary because of tight coupling of object types. Normally outside of Angular/Webpack we wouldn't need a fake SimpleFillSymbolProperties class
 let symbolProps = new SimpleFillSymbolProperties({
  style: 'none',
  outline: {
   width: 2,
   color: [0, 197, 255, 1]
  }
 });
 let highlightSymbol = new SimpleFillSymbol(symbolProps);
 graphic.symbol = highlightSymbol;
 if (graphicsLayerMap !== undefined) {
  // not the first time click on the map
  graphicsLayerMap.removeAll();
  graphicsLayerMap.add(graphic);
  } else {
  // if this is the first click on this map, add a graphicsLayer to the map
  // add graphic to GraphicsLayer
  let graphicsLayer = new GraphicsLayer({
   graphics: [graphic],
   listMode: 'hide'
  });
  this.mapService.webMaps[this.mapService.currentMap].layers.add(graphicsLayer);
 }
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Any help would be appreciated!

Re: GraphicsLayer removeall graphics come back after zoom

XueGao2 — Sun, 12 Dec 2021 03:29:35 GMT

I figured this one out. The graphic parameter that's passing in is a Graphic. In 4.x, it has a property - layer which is "references the layer in which the graphic is stored." and this is the layer that I'm clicking on. So I guess it adds the graphic to the layer that I click on. I also add it to the GraphicsLayer and I'm clearing it every time I click on the map. So there are two graphics I think.

The solution is to just pass in the geometry of the graphic and create a Graphic in highlightFeature(). Then add the new graphic to the GraphicsLayer. !

highlightFeature(geometry) {
    let theComponent = this;
    let firstClick = true;

    // SimpleFillSymbolProperties only necessary because of tight coupling of object types.  Normally outside of Angular/Webpack we wouldn't need a fake SimpleFillSymbolProperties class
    let symbolProps = new SimpleFillSymbolProperties({
      style: 'none',
      outline: {
        width: 2,
        color: [0, 197, 255, 1]
      }
    });
    let highlightSymbol = new SimpleFillSymbol(symbolProps);

    // Create a graphic and add the geometry and symbol to it
    let graphic = new Graphic({
      geometry: geometry,
      symbol: highlightSymbol
    });

    // check to see if the graphics layer exists already
    theComponent.mapService.webMaps[theComponent.mapService.currentMap].layers.items.forEach(function(layer){
      if (layer.type === 'graphics') {
        layer.removeAll();
        layer.add(graphic);
        firstClick = false;
      }
    });

    if (firstClick) {
      // first time click on this webmap
      // add graphiclayer to the webmap
      let graphicsLayerMap = new GraphicsLayer({
        listMode: 'hide'
      });
      theComponent.mapService.webMaps[this.mapService.currentMap].layers.add(graphicsLayerMap);

      // add graphic to the graphicslayer
      graphicsLayerMap.add(graphic);
    }
  }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍