Class GradientTheme

The GradientTheme class defines a gradient color thematic rendering of features based by a numeric attribute.

Inheritance

object

Style

GradientTheme

Implements

IThemeStyle

IStyle

Inherited Members

Style.MinVisible

Style.MaxVisible

Style.Enabled

Style.Opacity

Style.Equals(object)

Style.Equals(Style)

Style.GetHashCode()

object.Equals(object, object)

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Mapsui.Styles.Thematics

Assembly: Mapsui.dll

Syntax

public class GradientTheme : Style, IThemeStyle, IStyle

Constructors

GradientTheme(string, double, double, IStyle, IStyle)

Initializes a new instance of the GradientTheme class

Declaration

public GradientTheme(string columnName, double minValue, double maxValue, IStyle minStyle, IStyle maxStyle)

Parameters

Type	Name	Description
string	columnName	Name of column to extract the attribute
double	minValue	Minimum value
double	maxValue	Maximum value
IStyle	minStyle	Color for minimum value
IStyle	maxStyle	Color for maximum value

Remarks

The gradient theme interpolates linearly between two styles based on a numerical attribute in the data source. This is useful for scaling symbols, line widths, line and fill colors from numerical attributes.

Colors are interpolated between two colors, but if you want to interpolate through more colors (fx. a rainbow), set the TextColorBlend, LineColorBlend and FillColorBlend properties to a custom ColorBlend.

The following properties are scaled (properties not mentioned here are not interpolated):

Property	Remarks
Color	Red, Green, Blue and Alpha values are linearly interpolated.
Pen	The color, width, color of pens are interpolated. MiterLimit,StartCap,EndCap,LineJoin,DashStyle,DashPattern,DashOffset,DashCap,CompoundArray, and Alignment are switched in the middle of the min/max values.
Brush	Brush color are interpolated. Other brushes are not supported.
VectorStyle	MaxVisible, MinVisible, Line, Outline, Fill and SymbolScale are scaled linearly. Symbol, EnableOutline and Enabled switch in the middle of the min/max values.
LabelStyle	FontSize, BackColor, ForeColor, MaxVisible, MinVisible, Offset are scaled linearly. All other properties use min-style.

Creating a rainbow color blend showing colors from red, through yellow, green and blue depicting the population density of a country.

//Create two vector styles to interpolate between
Mapsui.Styles.VectorStyle min = new Mapsui.Styles.VectorStyle();
Mapsui.Styles.VectorStyle max = new Mapsui.Styles.VectorStyle();
min.Outline.Width = 1f; //Outline width of the minimum value
max.Outline.Width = 3f; //Outline width of the maximum value
//Create a theme interpolating population density between 0 and 400
Mapsui.Rendering.Thematics.GradientTheme popdens = new Mapsui.Rendering.Thematics.GradientTheme("POPDENS", 0, 400, min, max);
//Set the fill-style colors to be a rainbow blend from red to blue.
popdens.FillColorBlend = Mapsui.Rendering.Thematics.ColorBlend.Rainbow5;
myVectorLayer.Styles.Add(popdens);

Properties

ColumnName

Gets or sets the column name from where to get the attribute value

Declaration

public string ColumnName { get; set; }

Property Value

Type	Description
string

FillColorBlend

Gets or sets the ColorBlend used as Fill

Declaration

public ColorBlend? FillColorBlend { get; set; }

Property Value

Type	Description
ColorBlend

LineColorBlend

Gets or sets the ColorBlend used on lines

Declaration

public ColorBlend? LineColorBlend { get; set; }

Property Value

Type	Description
ColorBlend

Max

Gets or sets the maximum value of the gradient

Declaration

public double Max { get; set; }

Property Value

Type	Description
double

MaxStyle

Gets or sets the style for the maximum value

Declaration

public IStyle MaxStyle { get; set; }

Property Value

Type	Description
IStyle

Min

Gets or sets the minimum value of the gradient

Declaration

public double Min { get; set; }

Property Value

Type	Description
double

MinStyle

Gets or sets the style for the minimum value

Declaration

public IStyle MinStyle { get; set; }

Property Value

Type	Description
IStyle

TextColorBlend

Gets or sets the ColorBlend used on labels

Declaration

public ColorBlend? TextColorBlend { get; set; }

Property Value

Type	Description
ColorBlend

Methods

GetStyle(IFeature)

Returns the style based on a numeric DataColumn, where style properties are linearly interpolated between max and min values.

Declaration

public IStyle? GetStyle(IFeature row)

Parameters

Type	Name	Description
IFeature	row	Feature

Returns

Type	Description
IStyle	Style calculated by a linear interpolation between the min/max styles

Implements

IThemeStyle

IStyle

Extension Methods

StyleExtensions.GetStylesToApply(IStyle?, double)

StyleExtensions.ShouldBeApplied(IStyle?, double)