Table of Contents

Class GradientStyle

Namespace
ThinkGeo.Core
Assembly
ThinkGeo.Core.dll

This gradient style is a new style with the concept of GradientBrush. By specifying the LowerValue and its color, as well as the UpperValue and its color, we can set the color of each feature based on a column value using linear interpolation.

public class GradientStyle : Style
Inheritance
GradientStyle
Inherited Members

Constructors

GradientStyle(string, double, GeoColor, double, GeoColor)

This constructor creates a new instance by passing the ColumnName (which it will get the data from) as well as the lowerValue and its corresponding SolidBrush, and the upperValue and its corresponding SolidBrush.

public GradientStyle(string columnName, double lowerValue, GeoColor lowerColor, double upperValue, GeoColor upperColor)

Parameters

columnName string
lowerValue double
lowerColor GeoColor
upperValue double
upperColor GeoColor

Remarks

In this constructor, the NoDataValue defaults to -9999 and the NoDataBrush color is transparent.

GradientStyle(string, double, GeoColor, double, GeoColor, double, GeoColor)

This constructor creates a new instance by passing the ColumnName (which it will get the data from) as well as the lowerValue and its corresponding SolidBrush, the upperValue and its corresponding SolidBrush, and the NoDataValue and its corresponding SolidBrush.

public GradientStyle(string columnName, double lowerValue, GeoColor lowerColor, double upperValue, GeoColor upperColor, double noDataValue, GeoColor noDataColor)

Parameters

columnName string
lowerValue double
lowerColor GeoColor
upperValue double
upperColor GeoColor
noDataValue double
noDataColor GeoColor

Properties

ColumnName

This property gets and sets the column name used in the style.

public string ColumnName { get; set; }

Property Value

string

This property gets and sets the column name used in the style.

Remarks

None.

LowerColor

This property gets and sets the solid brush that is used for the style's lower value.

public GeoColor LowerColor { get; set; }

Property Value

GeoColor

This property gets and sets the solid brush that is used for the style's lower value.

Remarks

None.

LowerValue

This property gets and sets the lower value used in the style.

public double LowerValue { get; set; }

Property Value

double

This property gets and sets the lower value used in the style.

Remarks

None.

NoDataColor

This property gets and sets the solid brush that is used for the style's NoDataValue.

public GeoColor NoDataColor { get; set; }

Property Value

GeoColor

This property gets and sets the solid brush that is used for the style's NoDataValue.

Remarks

None.

NoDataValue

This property gets and sets the no data value used in the style.

public double NoDataValue { get; set; }

Property Value

double

This property gets and sets the no data value used in the style.

Remarks

None.

UpperColor

This property gets and sets the solid brush that is used for the style's upper value.

public GeoColor UpperColor { get; set; }

Property Value

GeoColor

This property gets and sets the solid brush that is used for the style's upper value.

Remarks

None.

UpperValue

This property gets and sets the upper value used in the style.

public double UpperValue { get; set; }

Property Value

double

This property gets and sets the upper value used in the style.

Remarks

None.

Methods

DrawCore(IEnumerable<Feature>, GeoCanvas, Collection<SimpleCandidate>, Collection<SimpleCandidate>)

This method draws the features on the view you provided.

protected override void DrawCore(IEnumerable<Feature> features, GeoCanvas canvas, Collection<SimpleCandidate> labelsInThisLayer, Collection<SimpleCandidate> labelsInAllLayers)

Parameters

features IEnumerable<Feature>

This parameter represents the features you want to draw on the view.

canvas GeoCanvas

This parameter represents the view you want to draw the features on.

labelsInThisLayer Collection<SimpleCandidate>

The labels will be drawn in the current layer only.

labelsInAllLayers Collection<SimpleCandidate>

The labels will be drawn in all layers.

Remarks

This virtual method is called from the concrete public method Draw. In this method, we take the features you passed in and draw them on the view you provided. Each style (based on its properties) may draw each feature differently.


When implementing this virtual method, consider each feature and its column data values. You can use the full power of the GeoCanvas to do the drawing. If you need column data for a feature, be sure to override the GetRequiredColumnNamesCore and add the columns you need to the collection. In many of the styles, we add properties to allow the user to specify which field they need; then, in the GetRequiredColumnNamesCore, we read that property and add it to the collection.

GetRequiredColumnNamesCore()

This method returns the column data for each feature that is required for the style to properly draw.

protected override Collection<string> GetRequiredColumnNamesCore()

Returns

Collection<string>

This method returns a collection of column names that the style needs.

Remarks

This abstract method is called from the concrete public method GetRequiredFieldNames. In this method, we return the column names that are required for the style to draw the feature properly. For example, if you have a style that colors areas blue when a certain column value is over 100, then you need to be sure you include that column name. This will ensure that the column data is returned to you in the feature when it is ready to draw.

In many of the styles, we add properties to allow the user to specify which field they need; then, in the GetRequiredColumnNamesCore we read that property and add it to the collection.