The custom theme generator is a special page of MapComplete, where one can create their own theme. It makes it easier to get started.
However, the custom theme generator is extremely buggy and built before some updates. This means that some features are _not_ available through the custom theme generator. The custom theme generator is good to get the basics of the theme set up, but you will have to edit the raw JSON-file anyway afterwards.
If you have your .json file, there are three ways to distribute your theme:
- Take the entire JSON-file and [base64](https://www.base64encode.org/) encode it. Then open up the url `https://mapcomplete.osm.be?userlayout=true#<base64-encoded-json-here>`. Yes, this URL will be huge; and updates are difficult to distribute as you have to send a new URL to everyone. This is however excellent to have a 'quick and dirty' test version up and running as these links can be generated from the customThemeGenerator and can be quickly shared with a few other contributors.
- Host the JSON file on a publicly accessible webserver (e.g. github) and open up `https://mapcomplete.osm.be?userlayout=<url-to-the-raw.json>`
- Ask to have your theme included into the official MapComplete - requirements below
### Getting your theme included into the official mapcomplete
Did you make an awesome theme that you want to share with the OpenStreetMap community? Have it included in the main application, which makes it more discoverable.
Your theme has to be:
0) Make sure the theme has an English version. This makes it easier for me to understand what is going on. The more other languages, the better of course!
1) Make sure your theme has good tagging
3) Make sure there are somewhat decent icons. Note that there is _no_ styleguide at the moment though.
The preferred way to add your theme is via a Pull Request. A Pull Request is less work for the maintainer (which makes it really easy and for me to add it) and your name will be included in the git history (so you'll be listed as contributor). If that is not possible, send the .Json-file and assets, e.g. as a zip in an issue, per email, ...
*Via a pull request:*
1) Fork this repository
2) Go to `assets/themes` and create a new directory `yourtheme`
3) Create a new file `yourtheme.json`, paste the theme configuration in there. You can find your theme configuration in the customThemeBuilder (the tab with the *Floppy disk* icon)
4) Copy all the images into this new directory: external assets can suddenly break and leak privacy
- Make sure the license is suitable, preferable a Creative Commons license. Attribution can be added at the bottom of this document
- If an SVG version is available, use the SVG version
- Make sure all the links in `yourtheme.json` are updated. You can use `./assets/themes/yourtheme/yourimage.svg` instead of the HTML link
5) Add your theme to the code base:
- Open [AllKnownLayouts.ts](https://github.com/pietervdvn/MapComplete/blob/master/Customizations/AllKnownLayouts.ts)
7) Happy with your theme? Time to open a Pull Request!
8) Thanks a lot for improving MapComplete!
The .JSON-format
----------------
There are three important levels in the .JSON-file:
- The toplevel describes the metadata of the entire theme. It contains the `title`, `description`, `icon`... of the theme. The most important object is `layers`, which is a list of objects describing layers.
- A `layer` describes a layer. It contains the `name`, `icon`, `tags of objects to download from overpass`, and especially the `icon` and a way to ask dynamically render tags and ask questions. A lot of those fields (`icon`, `title`, ...) are actually a `TagRendering`
- A `TagRendering` is an object describing a relationship between what should be shown on screen and the OSM-tagging. It works in two ways: if the correct tag is known, the appropriate text will be shown. If the tag is missing (and a question is defined), the question will be shown.
Every field is documented in the source code itself - you can find them here:
- [The top level `LayoutConfig`](https://github.com/pietervdvn/MapComplete/blob/master/Customizations/JSON/LayoutConfigJson.ts)
There are few tags available that are calculated for convenience - e.g. the country an object is located at. [An overview of all these metatags is available here](Docs/CalculatedTags.md)
Not publishing because 'it is not good enough'. _Share your theme, even if it is still not great, let the community help it improve_
### Thinking in terms of a question
Making a tagrendering as if it were a question only. If you have a question such as: _Does this bench have a backrest?_, it is very tempting to have as options _yes_ for `backrest=yes` and _no_ for `backrest=no`. However, when this data is known, it will simply show a lone _yes_ or _no_ which is very unclear.
The correct way to handle this is to use _This bench does have a backrest_ and _This bench does not have a backrest_ as answers.
One has to think first in terms of _what is shown to the user if it is known_, only then in terms of _what is the question I want to ask_
One layer should portray one kind of physical object, e.g. "benches" or "restaurants". It should contain all of them, disregarding other properties.
One should not make one layer for benches with a backrest and one layer for benches without. This is confusing for users and poses problems: what if the backrest status is unknown? What if it is some weird value?
Also, it isn't possible to 'move' an attribute to another layer.
Instead, make one layer for one kind of object and change the icon based on attributes.
_All_ data is downloaded in one go and cached locally first. The layer selection (bottom left of the live app) then selects _anything_ that matches the criteria. This match is then passed of to the rendering layer, which selects the layer independently. This means that a feature can show up, even if it's layer is unselected!
For example, in the [cyclofix-theme](https://mapcomplete.osm.org/cyclofix), there is the layer with _bike-wash_ for do it yourself bikecleaning - points marked with `service:bicycle:cleaning`. However, a bicycle repair shop can offer this service too!
If all the layers are deselected except the bike wash layer, a shop having this tag will still match and will still show up as shop.
