Table of Contents

Class IconValueStyle

Namespace
ThinkGeo.Core
Assembly
ThinkGeo.Core.dll

This class allows you to choose different icons based on values in the data of a feature.

public class IconValueStyle : PositionStyle
Inheritance
IconValueStyle
Inherited Members

Remarks

When you create an IconValueStyle, you need to add multiple IconValueItems to its collection. You input the column name in the IconValueStyle and it will compare the data's value to each IconValueItem's FieldValue. If they match, then it will draw the Feature using the properties of the IconValueItem. In this way, you can render different data with different icons or text.

The MinimumLength and MaximumLength properties are important because they are used to ensure that a properly sized icon is used to draw things like road signs. For example, you can set the minimum and maximum values so that the sign icon for a single-digit road number uses one icon, while a two-digit road uses another, wider sign icon in a separate IconValueItem.

Constructors

IconValueStyle()

This is the constructor for the class.

public IconValueStyle()

Remarks

If you use this constructor, then you need to set the required properties manually.

IconValueStyle(string)

This is the constructor for the class.

public IconValueStyle(string columnName)

Parameters

columnName string

This parameter is the column name you want to match on.

Remarks

None

IconValueStyle(string, IEnumerable<IconValueItem>)

This is the constructor for the class.

public IconValueStyle(string columnName, IEnumerable<IconValueItem> iconValueItems)

Parameters

columnName string

This parameter is the column name you want to match on.

iconValueItems IEnumerable<IconValueItem>

This parameter is the icon value items you want to match on.

Remarks

None

Properties

ColumnName

This property gets and sets the column name that will be used for the drawing and matching.

public string ColumnName { get; set; }

Property Value

string

This property gets the column name that will be used for the drawing and matching.

Remarks

This column name will be used to draw the text on the icon (if necessary) and to also match the value in the IconStyleItem.

IconValueItems

This property gets the collection of IconValueItems for matching.

public Collection<IconValueItem> IconValueItems { get; }

Property Value

Collection<IconValueItem>

This property gets the collection of IconValueItems for matching.

Remarks

You should create your IconValueItems and place them in this collection for consideration.

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 overridden 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 overriding this 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.

Exceptions

InvalidOperationException

In the event you attempt to call this method when the GeoCanvas's IsDrawing mode is false, it will throw an InvalidOperationException.

ArgumentNullException

If you pass a null as the view, we will throw an ArgumentNullException.

ArgumentNullException

If you pass a null as the features, we will throw an ArgumentNullException.

GetLabelingCandidateCore(Feature, GeoCanvas, GeoFont, float, float, double)

This method determines whether the specified feature is a good candidate to be labeled, based on the labeling properties set.

protected override Collection<LabelingCandidate> GetLabelingCandidateCore(Feature feature, GeoCanvas canvas, GeoFont font, float xOffsetInPixel, float yOffsetInPixel, double rotationAngle)

Parameters

feature Feature

This parameter is the feature that will be considered as a labeling candidate.

canvas GeoCanvas

This parameter is the view that will be used to draw the feature. This method will not draw on this view, but rather will use it to determine font size, etc.

font GeoFont
xOffsetInPixel float
yOffsetInPixel float
rotationAngle double

Returns

Collection<LabelingCandidate>

Remarks

This overridden method is called from the concrete public method Draw. In this method, we take the feature you passed in and determine if it is a candidate for labeling. If it is, then we will add it to the return collection. The algorithm to determine whether the label will draw is complex and determined by a number of properties and factors.

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 the column names that it 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.

Exceptions

ArgumentNullException

If columnName is null, we will throw an ArgumentNullException.