Colorizers
- 5 minutes to read
This document introduces the Map Colorizer, lists colorizer types, and explains how to create a colorizer and customize its settings in a map control.
The document consists of the following sections.
Overview
The Colorizer is used to automatically choose colors for map shapes based on shape data. This feature can be applied to the following MapShape class descendants that utilize the MapShapeBase.Fill property:
For example, you can use the map colorizer to create GDP, population or political maps.
Before using this feature, you will need to perform the following steps.
1) Specify the map control’s vector data.
For this, assign a MapDataAdapterBase class descendant object to the VectorLayer.Data property.
For example, let us use the ShapefileDataAdapter and specify a path to the Shapefile at design time. To do this, do the following.
- Click the MapControl’s smart tag to invoke its Tasks list.
In the Tasks list, click the Load Shapes from Shapefile link.
This automatically generates the following XAML:
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dxm="http://schemas.devexpress.com/winfx/2008/xaml/map"
x:Class="WpfApplication3.MainWindow"
Title="MainWindow" Height="350" Width="525">
<Grid>
<dxm:MapControl>
<dxm:VectorLayer>
<dxm:ShapeFileDataAdapter FileUri="INSERT_FILE_URI"/>
</dxm:VectorLayer>
</dxm:MapControl>
</Grid>
</Window>
- Specify a path to the Shapefile using the ShapefileDataAdapter.FileUri property.
2) Choose which colorizer type should be used in your application.
Currently, the following colorizer types are supported:
-
Represents the Choropleth colorizer, which shows statistical data over predefined regions (such as counties or states) by coloring or shading these regions.
-
Represents the Graph colorizer, which paints shapes that have a common border using different colors according to the Graph Coloring approach. For instance, the Graph colorizer can be used to create a political map.
-
Represents the Key-Color colorizer, which paints shapes according to their keys. The Key-Color colorizer can be used to add statistical information to a map.
Note
Shapes that have been obtained from a KML file can only be colored by the Graph Colorizer.
To add the colorizer to the map control, assign one of the MapColorizer class descendants to the VectorLayer.Colorizer property of the appropriate vector layer.
After you select a colorizer type, you can customize the map colorizer settings. The sections below describe how this can be done.
Choropleth Colorizer
To customize the choropleth colorizer, perform the following steps:
- Specify range stops (data splits in ranges) for the colorizer using the ChoroplethColorizer.RangeStops property.
The following XAML shows how this can be done.
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dxm="http://schemas.devexpress.com/winfx/2008/xaml/map"
x:Class="WpfApplication1.MainWindow"
Title="MainWindow" Height="350" Width="525">
<Grid>
<dxm:MapControl>
<dxm:MapControl.Colorizer>
<dxm:ChoroplethColorizer
RangeStops="0 3000 10000 18000 28000 44000 82000 185000 1000000 2500000 15000000">
</dxm:ChoroplethColorizer>
</dxm:MapControl.Colorizer>
</dxm:MapControl>
</Grid>
</Window>
Specify a set of colors in the ColorCollection object, which is accessed using the MapColorizer.Colors property. The colorizer automatically associates each color with the specified data range to colorize map shapes.
If you specify more ranges than colors, after reaching the last color in the collection, the colorizer will reuse colors starting from the beginning of the collection.
- Choose the value range distribution type you would like to use in the choropleth colorizer. The colorizer supports three types: ExponentialRangeDistribution, LinearRangeDistribution and LogarithmicRangeDistribution. To apply one of the range distribution types, use the ChoroplethColorizer.RangeDistribution property. By default, the linear range distribution is used.
To access information associated with a shape, specify the desired vector items attribute. For this, create a ShapeAttributeValueProvider object, set its attribute name (NamedAttributeProviderBase.AttributeName) and assign it to the ChoroplethColorizer.ValueProvider property.
After performing these steps, your XAML may appear as follows:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dxm="http://schemas.devexpress.com/winfx/2008/xaml/map"
x:Class="WpfApplication1.MainWindow"
Title="MainWindow" Height="350" Width="525">
<Grid>
<dxm:MapControl>
<dxm:MapControl.Colorizer>
<dxm:ChoroplethColorizer
RangeStops="0 3000 10000 18000 28000 44000 82000 185000 1000000 2500000 15000000">
<dxm:ChoroplethColorizer.RangeDistribution>
<dxm:ExponentialRangeDistribution/>
</dxm:ChoroplethColorizer.RangeDistribution>
<dxm:ChoroplethColorizer.Colors>
<Color>#5F8B95</Color>
<Color>#799689</Color>
<Color>#A2A875</Color>
<Color>#CEBB5F</Color>
<Color>#F2CB4E</Color>
<Color>#F1C149</Color>
<Color>#E5A84D</Color>
<Color>#D6864E</Color>
<Color>#C56450</Color>
<Color>#BA4D51</Color>
</dxm:ChoroplethColorizer.Colors>
<dxm:ChoroplethColorizer.ValueProvider>
<dxm:ShapeAttributeValueProvider AttributeName="GDP_MD_EST" />
</dxm:ChoroplethColorizer.ValueProvider>
</dxm:ChoroplethColorizer>
</dxm:MapControl.Colorizer>
<dxm:MapControl.Layers>
<dxm:VectorLayer>
<dxm:VectorLayer.ShapeLoader>
<dxm:ShapefileLoader FileUri="/WpfApplication1;component/Data/Countries.shp"/>
</dxm:VectorLayer.ShapeLoader>
</dxm:VectorLayer>
</dxm:MapControl.Layers>
</dxm:MapControl>
</Grid>
</Window>
Note that when the map control obtains data from a Shapefile, the vector item attributes are generated automatically. Thus, you can select which attribute should be used in your application. If an application uses manually generated map items, specify that the attributes of these items use the choropleth colorizer.
The image below shows the choropleth colorizer with a color scale legend that colors map contours based on GDP data from the Shapefile.
Example
To learn more about how to colorize map contours loaded from a Shapefile, see the following example.
Graph Colorizer
To colorize map contours, specify a set of colors via the MapColorizer.Colors property.
As a result, the map contours may appear as follows:
Example
This example shows how to use the graph colorizer.
Key-Color Colorizer
To colorize Map shapes using a key-color colorizer, do the following.
Specify the KeyColorColorizer.ItemKeyProvider property.
Create a few ColorizerKeyItem objects representing keys which will be used to select a color, and add them to the colorizer with KeyColorColorizer.Keys. Note that a key collection may be generated automatically.
Add several Color objects to the MapColorizer.Colors collection.
As a result, the map shapes appear as follows.
To learn more about how to colorize map items using a key-color colorizer, refer to How to: Colorize Map Items Using the Key Color Colorizer.