Difference Mode

Difference Mode allows you to subtract one polygon from another. The original feature will be replaced with the resulting difference feature.

You can handle Difference Mode for all layers on a map like this:

map.gm.enableGlobalDifferenceMode();
map.gm.disableGlobalDifferenceMode();
map.gm.toggleGlobalDifferenceMode();
map.gm.globalDifferenceModeEnabled();

// Or like this:
map.gm.enableMode('edit', 'difference');
map.gm.disableMode('edit', 'difference');
map.gm.toggleMode('edit', 'difference');
map.gm.isModeEnabled('edit', 'difference');

The following methods are available on map.gm:

Method	Returns	Description
enableGlobalDifferenceMode()	-	Enables global Difference Mode.
disableGlobalDifferenceMode()	-	Disables global Difference Mode.
toggleGlobalDifferenceMode()	-	Toggles global Difference Mode.
globalDifferenceModeEnabled()	Boolean	Returns true if global Difference Mode is enabled. false when disabled.

The following events are available on a map instance:

Event	Params	Description	Output
gm:difference	event	Fired during the difference operation.	map, originalFeatures, feature
gm:create	event	Fired during the difference operation.	map, feature, shape

The following events are available on a map instance:

Event	Params	Description	Output
gm:globaldifferencemodetoggled	event	Fired when Difference Mode is toggled.	enabled, map

You can also listen to specific Difference Mode events on the map instance like this:

map.on('gm:globaldifferencemodetoggled', (event) => {
  console.log(event);
});

Behavior

Difference mode operates by:

1. Selecting a target polygon (the one to subtract from)
2. Drawing or selecting another polygon that will be subtracted from the target
3. The original feature is replaced with the resulting difference feature

Supported Shapes

Difference mode supports the following feature types:

• Polygons
• Rectangles
• Circles

Live Difference Example