# Class: View

This documentation is for OpenLayers v10.9.0. The latest is v.

## ol/View~View

    import View from 'ol/View.js';

A View object represents a simple 2D view of the map.

This is the object to act upon to change the center, resolution, and rotation of the map.

A View has a `projection`. The projection determines the coordinate system of the center, and its units determine the units of the resolution (projection units per pixel). The default projection is Web Mercator (EPSG:3857).

### The view states

A View is determined by three states: `center`, `resolution`, and `rotation`. Each state has a corresponding getter and setter, e.g. `getCenter` and `setCenter` for the `center` state.

The `zoom` state is actually not saved on the view: all computations internally use the `resolution` state. Still, the `setZoom` and `getZoom` methods are available, as well as `getResolutionForZoom` and `getZoomForResolution` to switch from one system to the other.

### The constraints

`setCenter`, `setResolution` and `setRotation` can be used to change the states of the view, but any constraint defined in the constructor will be applied along the way.

A View object can have a resolution constraint, a rotation constraint and a center constraint.

The resolution constraint typically restricts min/max values and snaps to specific resolutions. It is determined by the following options: `resolutions`, `maxResolution`, `maxZoom` and `zoomFactor`. If `resolutions` is set, the other three options are ignored. See documentation for each option for more information. By default, the view only has a min/max restriction and allow intermediary zoom levels when pinch-zooming for example.

The rotation constraint snaps to specific angles. It is determined by the following options: `enableRotation` and `constrainRotation`. By default rotation is allowed and its value is snapped to zero when approaching the horizontal.

The center constraint is determined by the `extent` option. By default the view center is not constrained at all.

### Changing the view state

It is important to note that `setZoom`, `setResolution`, `setCenter` and `setRotation` are subject to the above mentioned constraints. As such, it may sometimes not be possible to know in advance the resulting state of the View. For example, calling `setResolution(10)` does not guarantee that `getResolution()` will return `10`.

A consequence of this is that, when applying a delta on the view state, one should use `adjustCenter`, `adjustRotation`, `adjustZoom` and `adjustResolution` rather than the corresponding setters. This will let view do its internal computations. Besides, the `adjust*` methods also take an `anchor` argument which allows specifying an origin for the transformation.

### Interacting with the view

View constraints are usually only applied when the view is at rest, meaning that no interaction or animation is ongoing. As such, if the user puts the view in a state that is not equivalent to a constrained one (e.g. rotating the view when the snap angle is 0), an animation will be triggered at the interaction end to put back the view to a stable state;

#### new View(options)

View.js, line 314

  Name | Type | Description
  --- | --- | ---
  `center` | Coordinate | undefined | The initial center for the view. If a user projection is not set, the coordinate system for the center is specified with the `projection` option. Layer sources will not be fetched if this is not set, but the center can be set later with `#setCenter`.
  `constrainRotation` | boolean | number (defaults to true) | Rotation constraint. `false` means no constraint. `true` means no constraint, but snap to zero near zero. A number constrains the rotation to that number of values. For example, `4` will constrain the rotation to 0, 90, 180, and 270 degrees.
  `enableRotation` | boolean (defaults to true) | Enable rotation. If `false`, a rotation constraint that always sets the rotation to zero is used. The `constrainRotation` option has no effect if `enableRotation` is `false`.
  `extent` | Extent | undefined | The extent that constrains the view, in other words, nothing outside of this extent can be visible on the map.
  `constrainOnlyCenter` | boolean (defaults to false) | If true, the extent constraint will only apply to the view center and not the whole extent.
  `smoothExtentConstraint` | boolean (defaults to true) | If true, the extent constraint will be applied smoothly, i.e. allow the view to go slightly outside of the given `extent`.
  `maxResolution` | number | undefined | The maximum resolution used to determine the resolution constraint. It is used together with `minResolution` (or `maxZoom`) and `zoomFactor`. If unspecified it is calculated in such a way that the projection's validity extent fits in a 256x256 px tile. If the projection is Spherical Mercator (the default) then `maxResolution` defaults to `40075016.68557849 / 256 = 156543.03392804097`.
  `minResolution` | number | undefined | The minimum resolution used to determine the resolution constraint. It is used together with `maxResolution` (or `minZoom`) and `zoomFactor`. If unspecified it is calculated assuming 29 zoom levels (with a factor of 2). If the projection is Spherical Mercator (the default) then `minResolution` defaults to `40075016.68557849 / 256 / Math.pow(2, 28) = 0.0005831682455839253`.
  `maxZoom` | number (defaults to 28) | The maximum zoom level used to determine the resolution constraint. It is used together with `minZoom` (or `maxResolution`) and `zoomFactor`. Note that if `minResolution` is also provided, it is given precedence over `maxZoom`.
  `minZoom` | number (defaults to 0) | The minimum zoom level used to determine the resolution constraint. It is used together with `maxZoom` (or `minResolution`) and `zoomFactor`. Note that if `maxResolution` is also provided, it is given precedence over `minZoom`.
  `multiWorld` | boolean (defaults to false) | If `false` the view is constrained so only one world is visible, and you cannot pan off the edge. If `true` the map may show multiple worlds at low zoom levels. Only used if the `projection` is global. Note that if `extent` is also provided it is given precedence.
  `constrainResolution` | boolean (defaults to false) | If true, the view will always animate to the closest zoom level after an interaction; false means intermediary zoom levels are allowed.
  `smoothResolutionConstraint` | boolean (defaults to true) | If true, the resolution min/max values will be applied smoothly, i. e. allow the view to exceed slightly the given resolution or zoom bounds.
  `showFullExtent` | boolean (defaults to false) | Allow the view to be zoomed out to show the full configured extent. By default, when a view is configured with an extent, users will not be able to zoom out so the viewport exceeds the extent in either dimension. This means the full extent may not be visible if the viewport is taller or wider than the aspect ratio of the configured extent. If showFullExtent is true, the user will be able to zoom out so that the viewport exceeds the height or width of the configured extent, but not both, allowing the full extent to be shown.
  `projection` | ProjectionLike (defaults to 'EPSG:3857') | The projection. The default is Spherical Mercator.
  `resolution` | number | undefined | The initial resolution for the view. The units are `projection` units per pixel (e.g. meters per pixel). An alternative to setting this is to set `zoom`. Layer sources will not be fetched if neither this nor `zoom` are defined, but they can be set later with `#setZoom` or `#setResolution`.
  `resolutions` | Array.<number> | undefined | Resolutions that determine the zoom levels if specified. The index in the array corresponds to the zoom level, therefore the resolution values have to be in descending order. It also constrains the resolution by the minimum and maximum value. If set the `maxResolution`, `minResolution`, `minZoom`, `maxZoom`, and `zoomFactor` options are ignored.
  `rotation` | number (defaults to 0) | The initial rotation for the view in radians (positive rotation clockwise, 0 means North).
  `zoom` | number | undefined | Only used if `resolution` is not defined. Zoom level used to calculate the initial resolution for the view.
  `zoomFactor` | number (defaults to 2) | The zoom factor used to compute the corresponding resolution.
  `padding` | Array.<number> (defaults to [0, 0, 0, 0]) | Padding (in css pixels). If the map viewport is partially covered with other content (overlays) along its edges, this setting allows to shift the center of the viewport away from that content. The order of the values is top, right, bottom, left.

  ##### Fires:

  - `change` (BaseEvent) - Generic change event. Triggered when the revision counter is increased.
  - `change:center` (ObjectEvent)
  - `change:resolution` (ObjectEvent)
  - `change:rotation` (ObjectEvent)
  - `error` (BaseEvent) - Generic error event. Triggered when an error occurs.
  - `propertychange` (ObjectEvent) - Triggered when a property is changed.

### Extends

- BaseObject

### Observable Properties

Name | Type | Settable | ObjectEvent type | Description
--- | --- | --- | --- | ---
`center` | Coordinate | undefined | yes | `change:center` | The center of the view.
`resolution` | number | undefined | yes | `change:resolution` | The resolution of the view.
`rotation` | number | yes | `change:rotation` | The rotation of the view in radians.

### Members

#### padding{Array.<number>} {undefined}

  Padding (in css pixels). If the map viewport is partially covered with other content (overlays) along its edges, this setting allows to shift the center of the viewport away from that content. The order of the values in the array is top, right, bottom, left. The default is no padding, which is equivalent to `[0, 0, 0, 0]`.

### Methods

#### adjustCenter(deltaCoordinates)

View.js, line 1546

  Adds relative coordinates to the center of the view. Any extent constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `deltaCoordinates` | Coordinate | Relative value to add.

#### adjustResolution(ratio, anchor)

View.js, line 1573

  Multiply the view resolution by a ratio, optionally using an anchor. Any resolution constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `ratio` | number | The ratio to apply on the view resolution.
  `anchor` | Coordinate | undefined | The origin of the transformation.

#### adjustRotation(delta, anchor)

View.js, line 1620

  Adds a value to the view rotation, optionally using an anchor. Any rotation constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `delta` | number | Relative value to add to the zoom rotation, in radians.
  `anchor` | Coordinate | undefined | The rotation center.

#### adjustZoom(delta, anchor)

View.js, line 1609

  Adds a value to the view zoom level, optionally using an anchor. Any resolution constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `delta` | number | Relative value to add to the zoom level.
  `anchor` | Coordinate | undefined | The origin of the transformation.

#### animate(var_args)

View.js, line 588

  Animate the view. The view's center, zoom (or resolution), and rotation can be animated for smooth transitions between view states. For example, to animate the view to a new zoom level:

      view.animate({zoom: view.getZoom() + 1});

  By default, the animation lasts one second and uses in-and-out easing. You can customize this behavior by including `duration` (in milliseconds) and `easing` options (see `ol/easing`).

  To chain together multiple animations, call the method with multiple animation objects. For example, to first zoom and then pan:

      view.animate({zoom: 10}, {center: [0, 0]});

  If you provide a function as the last argument to the animate method, it will get called at the end of an animation series. The callback will be called with `true` if the animation series completed on its own or `false` if it was cancelled.

  Animations are cancelled by user interactions (e.g. dragging the map) or by calling `view.setCenter()`, `view.setResolution()`, or `view.setRotation()` (or another method that calls one of these).

  Name | Type | Description
  --- | --- | ---
  `var_args` | Animation options. Multiple animations can be run in series by passing multiple options objects. To run multiple animations in parallel, call the method multiple times. An optional callback can be provided as a final argument. The callback will be called with a boolean indicating whether the animation completed without being cancelled.
  Name | Type | Description
  --- | --- | ---
  `center` | Coordinate | undefined | The center of the view at the end of the animation.
  `zoom` | number | undefined | The zoom level of the view at the end of the animation. This takes precedence over `resolution`.
  `resolution` | number | undefined | The resolution of the view at the end of the animation. If `zoom` is also provided, this option will be ignored.
  `rotation` | number | undefined | The rotation of the view at the end of the animation.
  `anchor` | Coordinate | undefined | Optional anchor to remain fixed during a rotation or resolution animation.
  `duration` | number (defaults to 1000) | The duration of the animation in milliseconds.
  `easing` | function | undefined | The easing function used during the animation (defaults to `inAndOut`). The function will be called for each frame with a number representing a fraction of the animation's duration. The function should return a number between 0 and 1 representing the progress toward the destination state.

#### beginInteraction()

View.js, line 1836

  Notify the View that an interaction has started. The view state will be resolved to a stable one if needed (depending on its constraints).

#### calculateExtent(size){Extent}

View.js, line 1000

  Calculate the extent for the current view state and the passed box size.

  Name | Type | Description
  --- | --- | ---
  `size` | Size | undefined | The pixel dimensions of the box into which the calculated extent should fit. Defaults to the size of the map the view is associated with. If no map or multiple maps are connected to the view, provide the desired box size (e.g. `map.getSize()`).

  ##### Returns:

  Extent.

#### cancelAnimations()

View.js, line 728

  Cancel any ongoing animations.

#### centerOn(coordinate, size, position)

View.js, line 1481

  Center on coordinate and view position.

  Name | Type | Description
  --- | --- | ---
  `coordinate` | Coordinate | Coordinate.
  `size` | Size | Box pixel size.
  `position` | Pixel | Position on the view to center on.

#### changed() inherited

Observable.js, line 68

  Increases the revision counter and dispatches a 'change' event.

#### dispatchEvent(event){boolean | undefined} inherited

events/Target.js, line 85

  Dispatches an event and calls all listeners listening for events of this type. The event parameter can either be a string or an Object with a `type` property.

  Name | Type | Description
  --- | --- | ---
  `event` | BaseEvent | string | Event object.

  ##### Returns:

  `false` if anyone called preventDefault on the event object or if any of the listeners returned false.

#### endInteraction(duration, resolutionDirection, anchor)

View.js, line 1850

  Notify the View that an interaction has ended. The view state will be resolved to a stable one if needed (depending on its constraints).

  Name | Type | Description
  --- | --- | ---
  `duration` | number | undefined | Animation duration in ms.
  `resolutionDirection` | number | undefined | Which direction to zoom.
  `anchor` | Coordinate | undefined | The origin of the transformation.

#### fit(geometryOrExtent, options)

View.js, line 1345

  Fit the given geometry or extent based on the given map size and border. The size is pixel dimensions of the box to fit the extent into. In most cases you will want to use the map size, that is `map.getSize()`. Takes care of the map angle.

  Name | Type | Description
  --- | --- | ---
  `geometryOrExtent` | SimpleGeometry | Extent | The geometry or extent to fit the view to.
  `options` | Options.
  Name | Type | Description
  --- | --- | ---
  `size` | Size | undefined | The size in pixels of the box to fit the extent into. Defaults to the size of the map the view is associated with. If no map or multiple maps are connected to the view, provide the desired box size (e.g. `map.getSize()`).
  `padding` | Array.<number> (defaults to [0, 0, 0, 0]) | Padding (in pixels) to be cleared inside the view. Values in the array are top, right, bottom and left padding.
  `nearest` | boolean (defaults to false) | If the view `constrainResolution` option is `true`, get the nearest extent instead of the closest that actually fits the view.
  `minResolution` | number (defaults to 0) | Minimum resolution that we zoom to.
  `maxZoom` | number | undefined | Maximum zoom level that we zoom to. If `minResolution` is given, this property is ignored.
  `duration` | number | undefined | The duration of the animation in milliseconds. By default, there is no animation to the target extent.
  `easing` | function | undefined | The easing function used during the animation (defaults to `inAndOut`). The function will be called for each frame with a number representing a fraction of the animation's duration. The function should return a number between 0 and 1 representing the progress toward the destination state.
  `callback` | function | undefined | Function called when the view is in its final position. The callback will be called with `true` if the animation series completed on its own or `false` if it was cancelled.

#### get(key){*} inherited

Object.js, line 136

  Gets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.

  ##### Returns:

  Value.

#### getAnimating(){boolean}

View.js, line 711

  Determine if the view is being animated.

  ##### Returns:

  The view is being animated.

#### getCenter(){Coordinate | undefined}

View.js, line 945

  Get the view center.

  ##### Returns:

  The center of the view.

#### getInteracting(){boolean}

View.js, line 720

  Determine if the user is interacting with the view, such as panning or zooming.

  ##### Returns:

  The view is being interacted with.

#### getKeys(){Array.<string>} inherited

Object.js, line 149

  Get a list of object property names.

  ##### Returns:

  List of property names.

#### getMaxResolution(){number}

View.js, line 1029

  Get the maximum resolution of the view.

  ##### Returns:

  The maximum resolution of the view.

#### getMaxZoom(){number}

View.js, line 1047

  Get the maximum zoom level for the view.

  ##### Returns:

  The maximum zoom level.

#### getMinResolution(){number}

View.js, line 1038

  Get the minimum resolution of the view.

  ##### Returns:

  The minimum resolution of the view.

#### getMinZoom(){number}

View.js, line 1067

  Get the minimum zoom level for the view.

  ##### Returns:

  The minimum zoom level.

#### getProjection(){Projection}

View.js, line 1096

  Get the view projection.

  ##### Returns:

  The projection of the view.

#### getProperties(){NoInfer.<Properties>} inherited

Object.js, line 158

  Get an object of all property names and values.

  ##### Returns:

  Object.

#### getResolution(){number | undefined}

View.js, line 1106

  Get the view resolution.

  ##### Returns:

  The resolution of the view.

#### getResolutionForExtent(extent, size){number}

View.js, line 1128

  Get the resolution for a provided extent (in map units) and size (in pixels).

  Name | Type | Description
  --- | --- | ---
  `extent` | Extent | Extent.
  `size` | Size | undefined | Box pixel size.

  ##### Returns:

  The resolution at which the provided extent will render at the given size.

#### getResolutionForZoom(zoom){number}

View.js, line 1313

  Get the resolution for a zoom level.

  Name | Type | Description
  --- | --- | ---
  `zoom` | number | Zoom level.

  ##### Returns:

  The view resolution for the provided zoom level.

#### getResolutions(){Array.<number> | undefined}

View.js, line 1116

  Get the resolutions for the view. This returns the array of resolutions passed to the constructor of the View, or undefined if none were given.

  ##### Returns:

  The resolutions of the view.

#### getRevision(){number} inherited

Observable.js, line 79

  Get the version number for this object. Each time the object is modified, its version number will be incremented.

  ##### Returns:

  Revision.

#### getRotation(){number}

View.js, line 1178

  Get the view rotation.

  ##### Returns:

  The rotation of the view in radians.

#### getZoom(){number | undefined}

View.js, line 1273

  Get the current zoom level. This method may return non-integer zoom levels if the view does not constrain the resolution, or if an interaction or animation is underway.

  ##### Returns:

  Zoom.

#### getZoomForResolution(resolution){number | undefined}

View.js, line 1288

  Get the zoom level for a resolution.

  Name | Type | Description
  --- | --- | ---
  `resolution` | number | The resolution.

  ##### Returns:

  The zoom level for the provided resolution.

#### on(type, listener){EventsKey | Array<EventsKey>} inherited

Observable.js, line 152

  Listen for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

  ##### Returns:

  Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

#### once(type, listener){EventsKey | Array<EventsKey>} inherited

Observable.js, line 164

  Listen once for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

  ##### Returns:

  Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

#### set(key, value, silent) inherited

Object.js, line 218

  Sets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.
  `value` | * | Value.
  `silent` | boolean | undefined | Update without triggering an event.

#### setCenter(center)

View.js, line 1650

  Set the center of the current view. Any extent constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `center` | Coordinate | undefined | The center of the view.

#### setConstrainResolution(enabled)

View.js, line 1087

  Set whether the view should allow intermediary zoom levels.

  Name | Type | Description
  --- | --- | ---
  `enabled` | boolean | Whether the resolution is constrained.

#### setMaxZoom(zoom)

View.js, line 1058

  Set a new maximum zoom level for the view.

  Name | Type | Description
  --- | --- | ---
  `zoom` | number | The maximum zoom level.

#### setMinZoom(zoom)

View.js, line 1078

  Set a new minimum zoom level for the view.

  Name | Type | Description
  --- | --- | ---
  `zoom` | number | The minimum zoom level.

#### setProperties(values, silent) inherited

Object.js, line 238

  Sets a collection of key-value pairs. Note that this changes any existing properties and adds new ones (it does not remove any existing properties).

  Name | Type | Description
  --- | --- | ---
  `values` | Partial.<NoInfer.<Properties>> | Values.
  `silent` | boolean | undefined | Update without triggering an event.

#### setResolution(resolution)

View.js, line 1682

  Set the resolution for this view. Any resolution constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `resolution` | number | undefined | The resolution of the view.

#### setRotation(rotation)

View.js, line 1693

  Set the rotation for this view. Any rotation constraint will apply.

  Name | Type | Description
  --- | --- | ---
  `rotation` | number | The rotation of the view in radians.

#### setZoom(zoom)

View.js, line 1703

  Zoom to a specific zoom level. Any resolution constrain will apply.

  Name | Type | Description
  --- | --- | ---
  `zoom` | number | Zoom level.

#### un(type, listener) inherited

Observable.js, line 173

  Unlisten for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

#### unset(key, silent) inherited

Object.js, line 262

  Unsets a property.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.
  `silent` | boolean | undefined | Unset without triggering an event.