[mkgmap-dev] builtin-tag-list

Wed Apr 24 19:16:31 BST 2013

Yes. The original idea was to move the routing code from the 
StyledConverter to the RoutingHook but I never realized that (don't know 
if it's possible...).

Some of the tags from the builtin-tag-list are also used on other places 
(e.g. type is used to load relations). Please keep that in mind.

WanMil

> Hi WanMil,
>
> ok, so I think I should remove the builtin-tag-list and implement a
> getUsedTags() method in StyledConverter. This would then also allow to
> remove the RoutingHook.
>
> OK?
>
> Gerd
>
>
> WanMil wrote
>>> Hi programmers,
>>
>> Hi Gerd,
>>
>>>
>>> while looking at the name-tag-list option I wondered again why we have
>>> so many different ways to maintain the "usedTags" HashMap which is
>>> finally
>>> used to filter OSM data in class OsmHandler.
>>>
>>> 1)We have a list coded in /resources/styles/builtin-tag-list. The tags
>>> listed here
>>> can be found in the java sources, but not all tags used in the sources
>>> are
>>> listed.
>>
>> This is historical. This was the initial list where all tags used in the
>> sources must be configured. This has the impact that the tag list is
>> static and does not reflect which options are used. So it's sometimes
>> larger than required which has a performance impact.
>>
>>>
>>> 2) Some sources use hard coded tag names and they have a method
>>> getUsedTags()
>>> to tell this fact to other routines.
>>
>> These are the OsmReadingHook classes. They use a getUsedTags() method.
>> These classes are called after reading the OSM file and before the style
>> is applied.
>>
>>>
>>> 3) Some hard coded tags are used in StyledConverter but they are added to
>>> the map
>>> in the RoutingHook, e.g. "access", "highway".
>>
>> This is a workaround to remove the tags from the builtin-tag-list
>> without modifying too much code. So if routing is enabled the routing
>> hook adds the tags required for routing. But these tags are not
>> evaluated by the RoutingHook itself but by the StyledConverter which has
>> no getUsedTags() method.
>>
>> Things are more complicate:
>> The LinkDestinationHook evaluates some tags like "destination" but it
>> does not return any of them in the getUsedTags() method. The reason is
>> that it must evaluate the tags only if they are used in the style file.
>> If destination is not referenced by the style file it makes no sense to
>> evaluate destination in the LinkDestinationHook so there is no need to
>> read the tag from the OSM file.
>>
>>>
>>> I'd prefer to have a common way to keep the map up to date, and I think
>>> that
>>> the best
>>> solution is to add the tag names in the source where they are used (and
>>> if
>>> they are used).
>>
>> At the moment I know about three ways:
>> 1. builtin-tag-list
>> 2. the getUsedTags() method of the OsmReadingHooks classes
>> 3. referencing in the style file
>>
>> I think the most you can achieve is to get rid of the builtin-tag-list.
>> In the past I have removed lots of tags here by implementing an
>> OsmReadingHook. Maybe some code can be moved from the StyledConverter to
>> a better place which also implements the getUsedTags() method.
>>
>>>
>>> What was the idea behind the builtin-tag-list ?
>>
>> See above. This was the first way to define tags that are used within
>> the code.
>>
>>>
>>> Gerd
>>>
>>
>> WanMil
>>
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>
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>
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>
>
>
>
>
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