Bivariate Renderers

Description:

This sample consists of two custom bivariate renderers: ColorBivariateRend and ColorSzBivariateRend. In general, bivariate renderers are useful for representing the relationship between two data distributions. Two variables are classified independently, and their combination is represented using some combination of symbol color and size.

The first renderer, ColorBivariateRend, combines two graduated color representations. On this renderer, symbol colors from the constituent representations are blended to produce the resultant symbology. The second renderer, ColorSzBivariateRend, combines a graduated color representation and a graduated symbol representation. On this renderer, the symbol color is taken from one representation, while symbol size is taken from the other representation to produce the resultant symbology. Each bivariate renderer is built from two ClassBreaksRenderers, and both implement ESRI's IBivariateRenderer interface. ColorBivariateRend also implements a custom interface, IColorBivariateRend.

The sample code for each renderer demonstrates how to design a feature renderer to draw custom layer symbology. IFeatureRenderer::SymbolByFeature is also demonstrated by both sets of code. ColorSzBivariateRenderer shows how to draw symbology in both the Geography and Annotation draw phases. This renderer also employs a strategy to draw symbols in order from large to small so that smaller features will appear on top.

Notes:

The TOC entry for ColorSzBivariateRenderer is not editable (same behavior as ESRI's BiUniqueValueRenderer)

IColorBivariateRend::ColorCombinationMethod controls how colors are blended in the ColorBivariateRenderer. There are three options: CIELAb, LabLCh, and RGBAverage. The first two options employ an ESRI AlgorithmicColorRamp object to interpolate a color halfway between the two colors in the applicable color space. The RGBAverage method averages the R,G, and B for the two colors. This method may yield darker than desirable merged colors with some color combinations.

Products:
ArcView: VB6

Platforms: Windows, Solaris

Requires: For VB Usage: An ArcMap session with the same layer added three times.

Minimum ArcGIS Release: 9.0

How to use:

[VB]

Register this sample's dll by compiling the sample or by using Regsvr32.exe.
Start ArcMap.
In the Visual Basic Editor, go to Tools > References. If this sample's dll does not appear in the Available References box, browse to the dll and add it. Check the box next to the dll's name. Dismiss the References dialog.

Copy-paste the following subroutines into a code module.


Public Sub ApplyColorBivariateRend()

' December 2, 2000
' ESRI ArcMap Development

' creates a new ColorBivariateRend
' sets MainRenderer equal to renderer from 1st layer
' sets VariationRenderer equal to renderer from 2nd layer
' assigns new renderer to 3rd layer
       
    Dim pMxDoc As IMxDocument
    Dim pFeatLayer As IGeoFeatureLayer
    Dim pFeatClass As IFeatureClass
    Dim pColorRend As IClassBreaksRenderer
    Dim pColorRend2 As IClassBreaksRenderer
    Dim i As Integer
    Dim pBivariateRend As IBivariateRenderer
    Dim pTwoWayColorRend As IColorBivariateRend
    Dim pFeatRend As IFeatureRenderer
    Dim bOK As Boolean
            
    Set pMxDoc = Application.Document
    Set pFeatLayer = pMxDoc.ActiveView.FocusMap.Layer(0)
    Set pColorRend = pFeatLayer.Renderer
    Set pFeatLayer = pMxDoc.ActiveView.FocusMap.Layer(1)
    Set pColorRend2 = pFeatLayer.Renderer

    Set pBivariateRend = New BivariateRenderers.ColorBivariateRend
    Set pBivariateRend.MainRenderer = pColorRend
    Set pBivariateRend.VariationRenderer = pColorRend2
    Set pTwoWayColorRend = pBivariateRend
    pTwoWayColorRend.ColorCombinationMethod = enuCIELabColorRamp
    
    pBivariateRend.CreateLegend

    Set pFeatLayer = pMxDoc.ActiveView.FocusMap.Layer(2)
    Set pFeatRend = pBivariateRend

    Set pFeatLayer.Renderer = pBivariateRend
    pMxDoc.UpdateContents
    pMxDoc.ActiveView.Refresh
End Sub


Public Sub ApplyColorSzBivariateRend()

' October 24, 2000
' ESRI ArcMap Development

' creates a new ColorSzBivariateRend
' sets MainRenderer equal to renderer from 1st layer (graduated colors)
' sets VariationRenderer equal to renderer from 2nd layer (graduated symbols)
' assigns new renderer to 3rd layer
       
    Dim pMxDoc As IMxDocument
    Dim pFeatLayer As IGeoFeatureLayer
    Dim pFeatClass As IFeatureClass
    Dim pColorRend As IClassBreaksRenderer
    Dim pColorRend2 As IClassBreaksRenderer
    Dim i As Integer
    Dim pBivariateRend As IBivariateRenderer
    Dim pFeatRend As IFeatureRenderer
    Dim bOK As Boolean
            
    Set pMxDoc = Application.Document
    Set pFeatLayer = pMxDoc.ActiveView.FocusMap.Layer(0)
    Set pColorRend = pFeatLayer.Renderer
    Set pFeatLayer = pMxDoc.ActiveView.FocusMap.Layer(1)
    Set pColorRend2 = pFeatLayer.Renderer

    Set pBivariateRend = New BivariateRenderers.ColorSzBivariateRend
    Set pBivariateRend.MainRenderer = pColorRend
    Set pBivariateRend.VariationRenderer = pColorRend2
    
    Set pFeatLayer = pMxDoc.ActiveView.FocusMap.Layer(2)
    Set pFeatRend = pBivariateRend

    Set pFeatLayer.Renderer = pBivariateRend
    pMxDoc.UpdateContents
    pMxDoc.ActiveView.Refresh
End Sub

Add a dataset to ArcMap that you wish to draw with one of the bivariate renderers.
Copy and paste the layer twice so that you have three copies of the layer in your map document.
Set up graduated color symbology on the first layer using the Symbology tab of the Layer Properties dialog box.
If you intend to use the ColorBivariateRend, set up graduated color symbology on the second layer as well. If you intend to use the ColorSzBivariateRend, set up graduated symbol symbology on the second layer.
Uncheck the visibity check box for the first two layers in the TOC. Finally, run the applicable macro (Tools --> Macros --> Run) to apply bivariate symbology to the third map layer.

VB6

Download the VB6 files

IColorBivariateRenderer.cls (view code)	Custom interface class.
ColorBivariateRenderer.cls (view code)	CoClass for the two way color bivariate renderer.
ColorSizeBivariateRenderer.cls (view code)	CoClass for the color-size bivariate renderer.
BivariateRenderers.vbp	Visual Basic project file.
BivariateRenderers.dll	The compiled component.

Download the files for all languages

Key Libraries: Carto
Key CoClasses:ClassBreaksRenderer, LegendGroup, LegendClass
Key Interfaces: IFeatureRenderer, IBivariateRenderer, IClassBreaksRenderer, IFeatureRenderer, ILegendGroup, IAlgorithmicColorRamp
Key Members: IFeatureRenderer::SymbolByFeature

EDN: ESRI Developer Network

Bivariate Renderers