Creates a new snapping control. A control is constructed with an editable layer and a
set of configuration objects for target layers. While the control is active, dragging vertices while
drawing new features or modifying existing features on the editable layer will engage snapping to features on
the target layers. Whether a vertex snaps to a feature on a target layer depends on the target layer
configuration.
Parameters
| options |
{Object} An object containing all configuration properties for the control. |
Valid options
| layer |
{OpenLayers.Layer.Vector}
The editable layer. Features from this layer that are digitized or modified may have vertices
snapped to features from any of the target layers.
|
| targets |
{Array(Object | OpenLayers.Layer.Vector)} A list of objects for configuring target
layers. See valid properties of the target objects below. If the items in the targets list are
vector layers (instead of configuration objects), the defaults from the <defaults> property will
apply. The editable layer itself may be a target layer, allowing newly created or edited features to
be snapped to existing features from the same layer. If no targets are provided the layer given in
the constructor (as <layer>) will become the initial target.
|
| defaults |
{Object} An object with default properties to be applied to all target objects.
|
| greedy |
{Boolean} Snap to closest feature in first target layer that applies. Default
is true. If false, all features in all target layers will be checked and the closest feature in all
target layers will be chosen. The greedy property determines if the order of the target layers is
significant. By default, the order of the target layers is significant where layers earlier in the
target layer list have precedence over layers later in the list. Within a single layer, the closest
feature is always chosen for snapping. This property only determines whether the search for a closer
feature continues after an eligible feature is found in a target layer.
|
Valid target properties
| layer |
{OpenLayers.Layer.Vector}
A target layer. Features from this layer will be eligible to act as snapping target for the editable
layer.
|
| tolerance |
{Float} The distance (in pixels) at which snapping may occur. Default is
10.
|
| node |
{Boolean} Snap to nodes (first or last point in a geometry) in target layer.
Default is true.
|
| nodeTolerance |
{Float} Optional distance at which snapping may occur for nodes specifically.
If none is provided, <tolerance> will be used.
|
| vertex |
{Boolean} Snap to vertices in target layer. Default is true. |
| vertexTolerance |
{Float} Optional distance at which snapping may occur for vertices specifically.
If none is provided, <tolerance> will be used.
|
| edge |
{Boolean} Snap to edges in target layer. Default is true. |
| edgeTolerance |
{Float} Optional distance at which snapping may occur for edges specifically.
If none is provided, <tolerance> will be used.
|
| filter |
{OpenLayers.Filter}
Optional filter to evaluate to determine if feature is eligible for snapping. If filter evaluates to
true for a target feature a vertex may be snapped to the feature.
|
| minResolution |
{Number} If a minResolution is provided, snapping to this target will only be
considered if the map resolution is greater than or equal to this value (the minResolution is inclusive).
Default is no minimum resolution limit.
|
| maxResolution |
{Number} If a maxResolution is provided, snapping to this target will only be
considered if the map resolution is strictly less than this value (the maxResolution is exclusive).
Default is no maximum resolution limit.
|