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40 lines
6.1 KiB
Markdown
40 lines
6.1 KiB
Markdown
API Doc for OfflineTilesBasic
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===============================
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There are two different libraries for taking tiles offline: `offline-tiles-basic-min.js` and `offline-tiles-advanced-min.js`. The basic library is for use with ArcGIS.com web maps and partial/intermittently offline use cases. You won't be able to restart or reload your app when using this library offline.
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If you have a requirement for restarting or reloading the app while offline then you should use the advanced library. The `offline-tiles-advanced-min.js` library lets you create a custom basemap layer that extends TiledMapServiceLayer.
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##O.esri.Tiles.OfflineTilesBasic
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The `offline-tiles-basic-min.js` library provides the following tools for working with with ArcGIS.com maps or tiled map services in partial-offline situations that don't require a browser restart or reload.
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###Constructor
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Constructor | Description
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--- | ---
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`O.esri.Tiles.OfflineTilesBasic()` | Creates an instance of the OfflineTilesBasic class. This library allows you to extend an ArcGISTiledMapServiceLayer with partial offline capability as well as manage the online/offline resynchronization process.
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###Properties
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Property | Value | Description
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--- | --- | ---
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`layer.showBlankTiles`| `true` | By default the library will show a 256x256 grey PNG image that says "NO TILE". To override this behavior, especially if you are using multiple tile layers and you don't want the grey "NO TILE" image to interfere then set this property to `false`.
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`layer.offline.proxyPath`| `null` | The default is `null`. If you have a CORS-enabled service then use the default. Don't forget to check your proxy configuration to allow connections for all possible services that you might be using. More information on using proxies with ArcGIS can be found here: [https://developers.arcgis.com/javascript/jshelp/ags_proxy.html](https://developers.arcgis.com/javascript/jshelp/ags_proxy.html).
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###Methods
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Methods | Returns | Description
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--- | --- | ---
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`extend(layer, callback, ` `state, dbConfig)`|`callback(boolean, string)` |Overrides an ArcGISTiledMapServiceLayer. Callback is called after indexedDB store is initialized and informs the application whether it is indexedDB is supported or not. <br><br>The `state` property is a boolean for specifying if the application is intializing the layer online (true) or offline (false). It defaults to `true`. When you first load the map it is a best practice to set this property to `true`. <br><br>`dbConfig` is an optional object that can be used to customize the database name (`dbName`) and the object store (`objectStoreName`) name. Example: `{dbName: "TILES_TEST", objectStoreName: "TILES"}`.
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`prepareForOffline(` `minLevel, maxLevel, extent, ` `reportProgress)` | `callback(number)` | Retrieves tiles and stores them in the local cache. For more information see [How To Use Tiles Library](howtousetiles.md).
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`goOffline()` | nothing | This method puts the layer in offline mode. When in offline mode, the layer will not fetch any tile from the remote server. It will look up the tiles in the IndexedDB database and display them in the layer. If the tile can't be found in the local database it will show up blank (even if there is actual connectivity). The pair of methods `goOffline()` and `goOnline() `allows the developer to manually control the behaviour of the layer. Used in conjunction with the offline dectection library, you can put the layer in the appropriate mode when the offline condition changes.
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`goOnline()` | nothing | This method puts the layer in online mode. When in online mode, the layer will behave as regular layers, fetching all tiles from the remote server. If there is no internet connectivity the tiles may appear thanks to the browsers cache, but no attempt will be made to look up tiles in the local database.
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`getLevelEstimation(extent,` `level, tileSize)` | {level, tileCount, sizeBytes} | Returns an object that contains the number of tiles that would need to be downloaded for the specified `"esri/geometry/Extent"`, zoom level `integer`, and the estimated byte size `integer`. This method is useful to give the user an indication of the required time and space before launching the actual download operation. The byte size estimation is very rough.
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`getExtentBuffer(buffer,extent)`| Extent | `buffer` property is an `integer`. `extent` property is an `"esri/geometry/Extent"`. Returns a new extent buffered by a given measurement that's based on map units. For example, if you are using mercator map projection then the buffer property would be in meters and the new extent would be returned in mercactor.
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`getTileUrlsByExtent(extent, level)` | Array | Returns an array of tile urls within a given map extent `"esri/geometry/Extent"` and zoom level `integer`.
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`deleteAllTiles(callback)` | `callback(boolean, errors)` | Clears the local cache of tiles.
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`getOfflineUsage(callback)` | `callback(size, error)` | Gets the size in bytes of the local tile cache.
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`getTilePolygons(callback)` | `callback(polygon, error)` | Gets polygons representing all cached tiles. This is helpful to give users a visual feedback of the current content of the tile cache.
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`saveToFile(filename, callback)` | `callback( boolean, error)` | Saves tile cache into a portable csv format.
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`loadFromFile(filename, callback)` | `callback( boolean, error)` | Reads a csv file into local tile cache.
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`estimateTileSize(callback)` | `callback(number)` | Retrieves one tile from a layer and then returns its size.
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`getMinZoom(callback)` | `callback(number)` | Returns the minimum zoom level of the layer. This is the zoom level farther away from the earth.
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`getMaxZoom(callback)` | `callback(number)` | Returns the maximum zoom level of the layer. This is the zoom level closest to the earth.
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`getMinMaxLOD(minZoomAdjust,` `maxZoomAdjust)` | `{min: zoomLevel, max: zoomLevel}` | Utility method for bracketing above and below your current Level of Detail. Use this in conjunction with setting the minLevel and maxLevel in `prepareForOffline()`. `minZoomAdjust` is an Integer specifying how far above the current layer you want to retrieve tiles. `maxZoomAdjust` is an Integer specifying how far below (closer to earth) the current layer you want to retrieve tiles |