# Major enhancements

## Tile animation

The displaying of tiles can now be animated, using CSS3 transitions. Transitions operate on the `opacity` property. Here's the CSS rule defined in OpenLayers' default theme:

    .olTileImage {
        -webkit-transition: opacity 0.2s linear;
        -moz-transition: opacity 0.2s linear;
        -o-transition: opacity 0.2s linear;
        transition: opacity 0.2s linear;
    }

People can override this rule to use other transition settings. To remove tile animation entirely use:

    .olTileImage {
        -webkit-transition: none;
        -moz-transition: none;
        -o-transition: all 0 none;
        transition: none;
    }

# Behavior Changes from Past Releases

## GPX API change

The `gpxns` API property has been removed. The GPX namespace is now defined in the `namespaces` property but is not intended to be overriden.

## Function return values

[Previously][prev] a few functions in the library displayed error messages and returned `undefined`, `null` or `false` if the parameters passed in were bad. In 2.12 these functions now just throw an error/exception. People relying on return values to know if a function call is successful may need to change their code. Here are the modified functions:

 * `OpenLayers.Bounds.add` throws a `TypeError` exception if `x` or `y` is null
 * `OpenLayers.LonLat.add` throws a `TypeError` exception if `lon` or `lat` is null
 * `OpenLayers.Pixel.add` throws a `TypeError` exception if `x` or `y` is null
 * `OpenLayers.Filter.Comparison.value2regex` throws an `Error` exception if `wildcard` equals to `"."`
 * `OpenLayers.Layer.PointTrack.addNodes` throws a `TypeError` exception if `endPoint` isn't actually a point
 * `OpenLayers.Layer.Vector.getFeatureFromEvent` throws an `Error` exception if the layer has no renderer

[prev]: https://github.com/openlayers/openlayers/commit/6e9a3e4c13e00c29daf28efd92b63c2390e69231

## Changes in formats WMTSCapabilities and SOSCapabilities

The structure of the object returned by `Format.WMTSCapabilities:read` and `Format.SOSCapabilities:read` has slightly changed.

For `WMTSCapabilities` the GET href used to be made available at `operationsMetadata.GetCapabilities.dcp.http.get`, the latter is now an array of objects with two properties: `url` and `constrains`. People using `operationsMetadata.GetCapabilities.dcp.http.get` in their applications should certainly use `operationsMetadata.GetCapabilities.dcp.http.get[0].url`.

Likewise for `SOSCapabilities`.

Looking at the tests is a good way to understand what the requires changes are. See [SOSCapabilities/v1_0_0.html](https://github.com/openlayers/openlayers/blob/master/tests/Format/SOSCapabilities/v1_0_0.html) and [WMTSCapabilities/v1_0_0.html](https://github.com/openlayers/openlayers/blob/master/tests/Format/WMTSCapabilities/v1_0_0.html).

 * Trac ticket: http://trac.osgeo.org/openlayers/ticket/3568
 * GitHub issue: https://github.com/openlayers/openlayers/pull/40


## Rico deprecation

We are deprecating the Rico classes/objects in OpenLayers. This has the following implications:

`Popup.AnchoredBubble` is deprecated. Its constructor now displays a deprecation message on the console. If you want popups with rounded corners either use `Popup.FramedClould`, or use `Popup.Anchored` and round corners using the [border-radius](https://developer.mozilla.org/en/CSS/border-radius) CSS property.

The `roundedCorner` option of `Control.LayerSwitcher` is deprecated, and it now defaults to `false`. Setting it to true results in deprecation messages being output on the console. If you still want to set `roundedCorner` to `true` (you should not!) you need to make sure that the Rico/Corner.js and Rico/Color.js scripts are loaded in the page. This can be ensured by adding Rico/Corner.js in the build profile. The controls.html example demonstrates how to use `border-radius` to round corners of a layer switcher:


    .olControlLayerSwitcher .layersDiv {
        border-radius: 10px 0 0 10px;
    }

See more detail in the Rico deprecation [pull request](https://github.com/openlayers/openlayers/pull/99).

In future releases we intend to move the Rico and `AnchoredBubble` code into deprecated.js. You really should consider stop using Rico-based functionalities in your applications.

## Changes in Geometry

The base `OpenLayers.Geometry` class no longer depends on `OpenLayers.Format.WKT` or `OpenLayers.Feature.Vector`.  If you want to make use of the `OpenLayers.Geometry.fromWKT` method, you must explicitly include the OpenLayers/Format/WKT.js file in your build.  

Without the WKT format included (by default), the `OpenLayers.Geometry::toString` method now returns "[object Object]."  Previously, it returned the Well-Known Text representation of the geometry.  To maintain the previous behavior, include the OpenLayers/Format/WKT.js file in your build.

## OSM and Bing Layers

`Layer.OSM` is now defined in its own script file, namely `OpenLayers/Layer/OSM.js`. So people using `Layer.OSM` should now include `OpenLayers/Layer/OSM.js`, as opposed to `OpenLayers/Layer/XYZ.js`, in their OpenLayers builds. (See https://github.com/openlayers/openlayers/issues/138)

The `OpenLayers.Tile.Image` class now has a method to get a canvas context for processing tiles. Since both OSM and Bing set Access-Control-Allow-Origin headers for their tiles, it is possible to manipulate a canvas that these tiles were rendered to even if the tiles come from a remote origin. Especially when working with custom OSM tilesets from servers that do not send Access-Control-Allow-Origin headers, it is now necessary to configure the layer with

    tileOptions: {crossOriginKeyword: null}

Both `OpenLayers.Layer.OSM` and `OpenLayers.Layer.Bing` do not have defaults for `maxExtent`, `maxResolutions` and `units` any more. This may break maps that are configured with a `maxResolution` of `156543.0339`, which was used in examples before 2.11, but is incorrect. The correct value is `156543.03390625`, but it is no longer necessary to specify a maxResolution, maxExtent and units if the correct resolution is set. See "Projection and Spherical Mercator" below.

## Projection & SphericalMercator

When working with Web Mercator layers (e.g. Google, Bing, OSM), it was previously necessary to configure the map or the base layer with the correct `projection`, `maxExtent`, `maxResolutions` and `units`. Now OpenLayers has defaults for WGS84 and Web Mercator in `OpenLayers.Projection.defaults`, so it is enough to provide the `projection`.

Old:

    new OpenLayers.Map({
        div: "map",
        projection: "EPSG:900913",
        maxResolution: 156543.03390625,
        maxExtent: new OpenLayers.Bounds(-20037508.34, -20037508.34, 20037508.34, 20037508.34),
        units: "m",
        layers: [
            new OpenLayers.Layer.Google("Google Streets"),
            new OpenLayers.Layer.OSM(null, null, {isBaseLayer: false, opacity: 0.7})
        ],
        zoom: 1
    });

New:

    new OpenLayers.Map({
        div: "map",
        projection: "EPSG:900913",
        layers: [
            new OpenLayers.Layer.Google("Google Streets"),
            new OpenLayers.Layer.OSM(null, null, {isBaseLayer: false, opacity: 0.7})
        ],
        zoom: 1
    });

In previous releases, coordinate transforms between EPSG:4326 and EPSG:900913 were defined in the SphericalMercator.js script.  In 2.12, these default transforms are included in the Projection.js script.  The Projection.js script is included as a dependency in builds with any layer types, so no special build configuration is necessary to get the web mercator transforms.

If you were previously using the `OpenLayers.Layer.SphericalMercator.forwardMercator` or `inverseMercator` methods, you may have to explicitly include the SphericalMercator.js script in your build.  The Google layer is the only layer that depends on the SphericalMercator mixin.  If you are not using the Google layer but want to use the SphericalMercator methods listed above, you have to explicitly include the SphericalMercator.js script in your build.

## QueryStringFilter

`OpenLayers.Protocol.HTTP` no longer requires `OpenLayers.Format.QueryStringFilter`. It you need this, make sure it is included in your build config file.

## Changes in getURLasync

The internal `OpenLayers.Layer.getURLasync` function now take a bound, a callback and a scope. The function no longer needs update the passed property but simply to return to url.

## Changes when base layer configured with wrapDateLine: true

Vector editing across the date line works reliably now. To make this work, OpenLayers won't zoom out to resolutions where more than one world is visible any more. For maps that have base layers with wrapDateLine set to false, no zoom restrictions apply.

## OpenLayers.Util.onImageLoadError no longer exists

To replace a tile that couldn't be loaded with a static image, create a css selector for the `.olImageLoadError` class (e.g. a `background-image`).

For more complex tile loading error handling, register a listener to the layer's `tileerror` event.

## Deprecated Components

A number of properties, methods, and constructors have been marked as deprecated for multiple releases in the 2.x series.  For the 2.12 release this deprecated functionality has been moved to a separate deprecated.js file.  If you use any of the constructors or methods below, you will have to explicitly include the deprecated.js file in your build (or add it in a separate `<script>` tag after OpenLayers.js).

 * OpenLayers.Class.isPrototype
 * OpenLayers.Class.create
 * OpenLayers.Class.inherit
 * OpenLayers.Util.clearArray
 * OpenLayers.Util.setOpacity
 * OpenLayers.Util.safeStopPropagation
 * OpenLayers.Util.getArgs
 * OpenLayers.nullHandler
 * OpenLayers.loadURL
 * OpenLayers.parseXMLString
 * OpenLayers.Ajax.* (all methods)
 * OpenLayers.Element.hide
 * OpenLayers.Element.show
 * OpenLayers.Element.getDimensions
 * OpenLayers.Tile.prototype.getBoundsFromBaseLayer
 * OpenLayers.Control.MouseDefaults
 * OpenLayers.Control.MouseToolbar
 * OpenLayers.Layer.Grid.prototype.getGridBounds
 * OpenLayers.Format.XML.prototype.concatChildValues
 * OpenLayers.Layer.WMS.Post
 * OpenLayers.Layer.WMS.Untiled
 * OpenLayers.Layer.MapServer.Untiled
 * OpenLayers.Tile.WFS
 * OpenLayers.Feature.WFS
 * OpenLayers.Layer.WFS
 * OpenLayers.Layer.MultiMap
 * OpenLayers.Layer.VirtualEarth
 * OpenLayers.Protocol.SQL
 * OpenLayers.Protocol.SQL.Gears
 * OpenLayers.Layer.Yahoo
 * OpenLayers.Layer.GML
 * OpenLayers.Geometry.Rectangle

In addition, OpenLayers no longer modifies any native prototypes or objects by default.  If you rely on any of the following, you'll need to include deprecated.js explicitly to get the same behavior.

 * String.prototype.startsWith
 * String.prototype.contains
 * String.prototype.trim
 * String.prototype.camelize
 * Function.prototype.bind
 * Function.prototype.bindAsEventListener
 * Event.stop

