Hide Table of Contents
esri
esri/arcgis
esri/dijit
esri/dijit/analysis
esri/dijit/geoenrichment
esri/dijit/geoenrichment/ReportPlayer
esri/geometry
esri/layers
esri/renderers
esri/symbols
esri/tasks
esri/tasks/datareviewer
esri/tasks/geoenrichment
esri/tasks/locationproviders
Class: DotDensityRenderer
[ AMD Module Require | Legacy Module Require ]
require(["esri/renderers/DotDensityRenderer"], function(DotDensityRenderer) { /* code goes here */ });
Description
(Added at v3.7)
The DotDensityRenderer provides the ability to create dot density visualizations on data. A dot density map can be used to visualize the variation in spatial density of a discrete spatial phenomenon. You can visualize only one variable (for example, 1 dot = 25,000 acres harvested) or multiple variables (for example, 1 green dot = 10,000 acres of corn harvested; 1 brown dot = 10,000 acres of wheat harvested) on one map.
Things to consider when making dot density maps:
- The
fieldsproperty allows you to specify multiple fields. You may utilize this property to visualize multiple variables on one map with different colors. For example, use different colors to show the distribution of various ethnic groups. dotValueanddotSizedrive the visual effects on your map. A good practice is to set the size and value of the dot so that the feature with the highest value in the layer is ~80% covered in dots.- The density on map always changes as the user zooms in or zooms out. Use the
ScaleDependentRendererto set a unique dot density renderer for each scale or zoom range, so thedotValueanddotSizecan vary across multiple scale ranges. - Dot density maps tend to break down at larger scales. Users start seeing patterns in the random distribution of the dots that do not exist in reality. For example, dot density visualizations on county datasets should only be viewed at the state or regional level.
- Dot density maps should always use equal area projections to ensure the density is based on the same area measurement everywhere on maps, although WebMercator could be acceptable at larger scales, as the exaggeration of area becomes negligible.
- Use popups to clearly communicate the actual value of the feature, so the user can explore the map visually and interactively.
Samples
Search for samples that use this class.Class hierarchy
esri/renderers/Renderer |_esri/renderers/DotDensityRenderer
Constructors
| Name | Summary |
|---|---|
| new DotDensityRenderer(params) | Creates a new instance of dot density renderer. |
Properties
| Name | Type | Summary |
|---|---|---|
| backgroundColor | Color | The color to be used for the background of the symbol. |
| dotShape | String | The shape to be used for the dot. |
| dotSize | Number | The size of the dot in pixels. |
| dotValue | Number | The value that a dot represents. |
| fields | Object[] | An array of objects, where each object defines a field to be mapped and its color. |
| outline | LineSymbol | The line symbol to use on the outline of the feature. |
Methods
| Name | Return type | Summary |
|---|---|---|
| getColor(graphic, options?) | Color | Gets the color for the Graphic. |
| getOpacity(graphic, options?) | Number | Returns the opacity value for the specified graphic. |
| getRotationAngle(graphic, options?) | Number | Returns the angle of rotation (in degrees) for the graphic calculated using rotationInfo. |
| getSize(graphic, options?) | Number | Return the symbol size (in pixels) for the graphic, calculated using sizeInfo. |
| getSymbol(graphic) | Symbol | Gets the symbol for the Graphic. |
| setBackgroundColor(color) | None | Updates the background color of the shape. |
| setDotSize(size) | None | Updates the size of the dot. |
| setDotValue(value) | None | Updates the value that a dot represents. |
| setOutline(outline) | None | Updates the outline symbol of the shape. |
| toJson() | Object | Converts object to its ArcGIS Server JSON representation. |
Constructor Details
Creates a new instance of dot density renderer.
Parameters:
< |
Required | An object with various options. Refer to the options table for details. |
params properties: < |
Optional | The color to be used for the background of the symbol. By default no background color will be applied. |
< |
Optional | The shape to be used for the dot. Can be a "square" or a "circle". The default is a "square". |
< |
Optional | The size of the dot in pixels. |
< |
Required | The value that a dot represents.
Typically one dot is more than one. For example if the value of the field being mapped is 150,000 and the dotValue is 1,000 the feature will have 150 dots randomly placed within the boundary of the feature. Values are rounded up. A value of 499 would not get a dot. A value of 500 would get one dot. |
< |
Required | An array of objects, where each object defines a field to be mapped and its color.
[
{
name: <String>,
color : <Color>
},
...
]
|
< |
Optional | The line symbol to use on the outline of the feature. By default no outline will be applied. |
Sample:
require(["esri/renderers/DotDensityRenderer", ... ], function(DotDensityRenderer, ... ){
var dotDensityRenderer = new DotDensityRenderer({
fields: [{
name: "M163_07",
color: new Color([52, 114, 53])
}],
dotValue: 4000,
dotSize: 2
});
layer.setRenderer(dotDensityRenderer);
});Property Details
<Color
ColorThe color to be used for the background of the symbol. By default no background color will be applied.
<String
StringThe shape to be used for the dot.
Known values:
"square" | "circle"Default value:
"square"<Number
NumberThe size of the dot in pixels.
<Number
NumberThe value that a dot represents.
<Object[]
Object[]An array of objects, where each object defines a field to be mapped and its color. Required.
[
{
name: <String>,
color : <Color>
},
...
]
- Name represents the name of the field to be mapped.
- Color represents the color of the dot.
<LineSymbol
LineSymbolThe line symbol to use on the outline of the feature. By default no outline will be applied.
Method Details
Gets the color for the Graphic. (Added at v3.8)
Return type:
ColorParameters:
< |
Required | Graphic to get color from. |
< |
Optional | This optional parameter supports colorInfo. If none is provided, the Renderer.colorInfo will be used. |
Returns the opacity value for the specified graphic. This is calculated using the opacityInfo definition. (Added at v3.11)
Return type:
NumberParameters:
< |
Required | Returns the opacity value appropriate for the given graphic. This value is calculated based on the opacityInfo definition. |
< |
Optional | This optional parameter supports opacityInfo. If none is provided, the Renderer.opacityInfo will be used. |
Returns the angle of rotation (in degrees) for the graphic calculated using rotationInfo. (Added at v3.7)
Return type:
NumberParameters:
< |
Required | An input graphic for which you want to get the angle of rotation. |
< |
Optional | This optional parameter supports rotationInfo. If none is provided, the Renderer.rotationInfo will be used. |
Return the symbol size (in pixels) for the graphic, calculated using
sizeInfo. (Added at v3.7)Return type:
NumberParameters:
< |
Required | The graphic for which you want to calculate the symbol size. |
< |
Optional | This optional parameter supports sizeInfo. If none is provided, the Renderer.sizeInfo will be used.
|
Gets the symbol for the Graphic.
Return type:
SymbolParameters:
< |
Required | Graphic to symbolize. Used when creating a custom renderer. |
Updates the background color of the shape. For the changes to take effect, you need to call GraphicsLayer.redraw after calling this method.
Parameters:
< |
Required | Background color. |
Updates the size of the dot. Size represents screen pixels. For the changes to take effect, you need to call GraphicsLayer.redraw after calling this method.
Parameters:
< |
Required | The size of the dot in pixels. |
Updates the value that a dot represents. For the changes to take effect, you need to call GraphicsLayer.redraw after calling this method.
Parameters:
< |
Required | The value that a dot represents. |
Updates the outline symbol of the shape. For the changes to take effect, you need to call GraphicsLayer.redraw after calling this method.
Parameters:
< |
Required | The line symbol to use on the outline of the feature. |
Converts object to its ArcGIS Server JSON representation. (Added at v2.1)
Return type:
Object