Unique value renderer

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Render features in a layer using a distinct symbol for each unique attribute value.

screenshot

Use case

A unique value renderer allows you to symbolize features in a layer based on one or more matching attributes. This is typically done by using unique colors, fill styles, or images to represent features with equal values in a string field. A unique value renderer could be used to show different types of trees on a vegetation map by using a symbols corresponding to matching name attributes.

How to use the sample

The map with the symbolized feature layer will be shown automatically when the sample loads.

How it works

This sample demonstrates how to use a UniqueValueRenderer to style different features in a FeatureLayer. Using the UniqueValueRenderer allows for separate symbols to be used for features that have a specific value in a certain field. In this case, the field is state abbreviations in the USA. Multiple fields can be used; this sample only uses one:

  1. Multiple SimpleFillSymbolss are defined for each type of feature we want to render differently.
  2. SimpleFillSymbols can be applied to polygon features, which is the type of feature used for this ServiceFeatureTable.
  3. Separate UniqueValues objects are created which define the values in the renderer field and what symbol should be used to render matching features.
  4. A default symbol is created to render all features that do not match the UniqueValues defined.

Relevant API

  • FeatureLayer
  • ServiceFeatureTable
  • SimpleFillSymbol
  • SimpleLineSymbol
  • UniqueValue
  • UniqueValueRenderer

About the data

The map shows U.S. states symbolized by subregion. Symbols are defined for Pacific, Mountain, and West South Central states. All other features are symbolized with the default symbol.

Tags

draw, renderer, symbol, symbology, values

Sample Code

Unique_Value_Renderer.qmlUnique_Value_Renderer.cppUnique_Value_Renderer.h
                               
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// [WriteFile Name=Unique_Value_Renderer, Category=DisplayInformation]
// [Legal]
// Copyright 2016 Esri.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// [Legal]

import QtQuick 2.6
import QtQuick.Controls 2.2
import Esri.Samples 1.0

Unique_Value_RendererSample {
    clip: true
    width: 800
    height: 600

    // add a mapView component
    MapView {
        anchors.fill: parent
        objectName: "mapView"
    }
}

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