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.
Description:This method returns a collection of column names that it needs.
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 canvas 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.
This property controls the ratio of points on the screen to numeric value in the data. For example, if you have a value of 100 in the data and you have the ratio set to 1, then you will get 100 points drawn. A ratio of higher than 1 will draw more points than the data value; in our example, a ratio of 2 will draw 200 points. Conversely, a ratio of less than 1 will draw fewer points than the data value; in our example, a ratio of 0.5 would draw 50 points.