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author | Minh Nguyễn <mxn@1ec5.org> | 2017-05-09 18:36:20 -0700 |
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committer | Minh Nguyễn <mxn@1ec5.org> | 2017-05-16 16:42:31 -0700 |
commit | 30b919196b72351c43a5834b66a36068c0588fe0 (patch) | |
tree | f3bcc000688ba3c32bb19c9ab44e4e9d39f51013 /platform/darwin/docs | |
parent | c7acb5516b7575feb20f20d6f6cfaabede97c948 (diff) | |
download | qtlocation-mapboxgl-30b919196b72351c43a5834b66a36068c0588fe0.tar.gz |
[ios, macos] Factored out tile URL template guide
Factored out redundant tile URL template documentation from the MGLRasterSource and MGLVectorSource documentation into a jazzy guide. This documentation used to live in one place, on a method on MGLTileSource, but that method had to be moved to MGLTileSource’s concrete subclasses. A jazzy guide is easier to link to, in any case.
Diffstat (limited to 'platform/darwin/docs')
-rw-r--r-- | platform/darwin/docs/guides/Tile URL Templates.md.ejs | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/platform/darwin/docs/guides/Tile URL Templates.md.ejs b/platform/darwin/docs/guides/Tile URL Templates.md.ejs new file mode 100644 index 0000000000..78fb297138 --- /dev/null +++ b/platform/darwin/docs/guides/Tile URL Templates.md.ejs @@ -0,0 +1,109 @@ +<% + const os = locals.os; + const iOS = os === 'iOS'; + //const macOS = os === 'macOS'; + //const cocoaPrefix = iOS ? 'UI' : 'NS'; +-%> +<!-- + This file is generated. + Edit platform/darwin/scripts/generate-style-code.js, then run `make darwin-style-code`. +--> +# Tile URL Templates + +`MGLTileSource` objects, specifically `MGLRasterSource` and `MGLVectorSource` +objects, can be created using an initializer that accepts an array of tile URL +templates. Tile URL templates are strings that specify the URLs of the vector +tiles or raster tile images to load. A template resembles an absolute URL, but +with any number of placeholder strings that the source evaluates based on the +tile it needs to load. For example: + +* `http://www.example.com/tiles/{z}/{x}/{y}.pbf` could be + evaluated as `http://www.example.com/tiles/14/6/9.pbf`. +* `http://www.example.com/tiles/{z}/{x}/{y}{ratio}.png` could be + evaluated as `http://www.example.com/tiles/14/6/9@2x.png`. + +Tile URL templates are also used to define tilesets in TileJSON manifests or +[`raster`](https://www.mapbox.com/mapbox-gl-js/style-spec/#sources-raster-tiles) +and +[`vector`](https://www.mapbox.com/mapbox-gl-js/style-spec/#sources-vector-tiles) +sources in style JSON files. See the +[TileJSON specification](https://github.com/mapbox/tilejson-spec/tree/master/2.2.0) +for information about tile URL templates in the context of a TileJSON or style +JSON file. + +Tile sources support the following placeholder strings in tile URL templates, +all of which are optional: + +<table> +<thead> +<tr><th>Placeholder string</th><th>Description</th></tr> +</thead> +<tbody> +<tr> + <td><code>{x}</code></td> + <td>The index of the tile along the map’s x axis according to Spherical + Mercator projection. If the value is 0, the tile’s left edge corresponds + to the 180th meridian west. If the value is 2<sup><var>z</var></sup>−1, + the tile’s right edge corresponds to the 180th meridian east.</td> +</tr> +<tr> + <td><code>{y}</code></td> + <td>The index of the tile along the map’s y axis according to Spherical + Mercator projection. If the value is 0, the tile’s tile edge corresponds + to arctan(sinh(π)), or approximately 85.0511 degrees north. If the value + is 2<sup><var>z</var></sup>−1, the tile’s bottom edge corresponds to + −arctan(sinh(π)), or approximately 85.0511 degrees south. The y axis is + inverted if the <code>options</code> parameter contains + <code>MGLTileSourceOptionTileCoordinateSystem</code> with a value of + <code>MGLTileCoordinateSystemTMS</code>.</td> +</tr> +<tr> + <td><code>{z}</code></td> + <td>The tile’s zoom level. At zoom level 0, each tile covers the entire + world map; at zoom level 1, it covers ¼ of the world; at zoom level 2, + <sup>1</sup>⁄<sub>16</sub> of the world, and so on. For tiles loaded by + a <code>MGLRasterSource</code> object, whether the tile zoom level + matches the map’s current zoom level depends on the value of the + source’s tile size as specified in the + <code>MGLTileSourceOptionTileSize</code> key of the <code>options</code> + parameter.</td> +</tr> +<tr> + <td><code>{bbox-epsg-3857}</code></td> + <td>The tile’s bounding box, expressed as a comma-separated list of the + tile’s western, southern, eastern, and northern extents according to + Spherical Mercator (EPSG:3857) projection. The bounding box is typically + used with map services conforming to the + <a href="http://www.opengeospatial.org/standards/wms">Web Map Service</a> + protocol.</td> +</tr> +<tr> + <td><code>{quadkey}</code></td> + <td>A quadkey indicating both the tile’s location and its zoom level. The + quadkey is typically used with + <a href="https://msdn.microsoft.com/en-us/library/bb259689.aspx">Bing Maps</a>. + </td> +</tr> +<tr> + <td><code>{ratio}</code></td> + <td>A suffix indicating the resolution of the tile image. The suffix is the + empty string for standard resolution displays and <code>@2x</code> for +<% if (iOS) { -%> + Retina displays, including displays for which <code>UIScreen.scale</code> + is 3. +<% } else { -%> + Retina displays. +<% } -%> + </td> +</tr> +<tr> + <td><code>{prefix}</code></td> + <td>Two hexadecimal digits chosen such that each visible tile has a + different prefix. The prefix is typically used for domain sharding.</td> +</tr> +</tbody> +</table> + +For more information about the `{x}`, `{y}`, and `{z}` placeholder strings, +consult the +[OpenStreetMap Wiki](https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames). |