Class MaplibreMeasureControl

Constructor

The precision of area value. Using setter to override the value if you want.

Default is undefined. If undefined is set, the unit is converted automatically based on the value.

For metric system:

• Values >= 1,000,000m² are converted to square kilometers
• Values >= 10,000m² are converted to hectares
• Values >= 100m² are converted to ares
• Values < 100m² are kept as square meters

For imperial system:

• Values >= 2,589,988.11m² (1 square mile) are converted to square miles
• Values >= 4,046.856m² (1 acre) are converted to acres
• Values >= 0.83612736m² (1 square yard) are converted to square yards
• Values < 0.83612736m² are converted to square feet

If a specific unit is specified (e.g., 'square meters', 'square kilometers', 'ares', 'hectares', 'square feet', 'square yards', 'acres', 'square miles'), the value is always returned in that unit.

Custom conversion function can be also set to this property. The function receives the area value in square meters and should return an object with area and unit properties.

An example of custom conversion function:

const customConversion: AreaUnitCallBackType = (valueInSquareMeters) => {
   if (valueInSquareMeters >= 1000) {
	  return { area: valueInSquareMeters / 1000, unit: 'km²' };
 } else {
	return { area: valueInSquareMeters, unit: 'm²' };
};
control.areaUnit = customConversion;
Copy

The flag of whether computing elevation. Default is false. Using setter to override the value if you want.

The precision of distance value. It will be set different value when distance unit is changed. Using setter to override the value if you want.

Default is undefined. If undefined is set, the unit is converted automatically based on the value.

For metric system:

• Values >= 1000m are converted to kilometers
• Values >= 1m are kept as meters
• Values < 1m are converted to centimeters

For imperial system:

• Values >= 5280ft (1 mile) are converted to miles
• Values >= 1ft are kept as feet
• Values < 1ft are converted to inches

If a specific unit is specified (e.g., 'km', 'm', 'cm', 'mi', 'ft', 'in'), the value is always returned in that unit.

Custom conversion function can be also set to this property. The function receives the distance value in meters and should return an object with distance and unit properties. An example of custom conversion function:

const customConversion: DistanceUnitCallBackType = (valueInMeter) => {
   if (valueInMeter >= 1000) {
	  return { distance: valueInMeter / 1000, unit: 'km' };
  } else {
	return { distance: valueInMeter, unit: 'm' };
 };
};
control.distanceUnit = customConversion;
Copy

Get/Set font glyph for measure control layers

As default, this maesure control uses maplibre's default font glyphs(Open Sans Regular,Arial Unicode MS Regular) described at https://maplibre.org/maplibre-style-spec/layers/#text-font

If you are using your own maplibre style or different map privider, you probably need to set the font glyphs to match your maplibre style.

Font glyph availability depends on what types of glyphs are supported by your maplibre style (e.g., Carto, Openmap tiles, Protomap, Maptiler, etc.) Please make sure the font glyphs are available in your maplibre style.

Usage:

const drawControl = new MaplibreMeasureControl()
drawControl.fontGlyphs = ['Open Sans Italic']
map.addControl(drawControl)
Copy

Measure unit symbols. If you want to change the default symbol, please overwrite the symbol by this option.

The unit of measurement can be metric or imperial. Default is metric. The measuring result will be recalculated once new value is set

Activate Terra Draw to start drawing

clean maplibre style to filter only for terradraw related layers or without them. If options are not set, returns original style given to the function.

This can be useful incase users only want to get terradraw related layers or without it.

Usage: cleanStyle(map.getStyle, { excludeTerraDrawLayers: true}) cleanStyle(map.getStyle, { onlyTerraDrawLayers: true})

add the plugin control to maplibre

Remove the plugin control from maplibre

Recalculate area and distance in TerraDraw snapshot

if you use addFeatures to restore GeoJSON features to TerraDraw, this recalc method needs to be called to re-measure again.

For example, the below code is an example usage.

drawInstance?.addFeatures(initData);
map?.once('idle', ()=>{
  drawControl.recalc()
})
Copy