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30 lines
1.3 KiB
Markdown
30 lines
1.3 KiB
Markdown
## Why not use canvas rather than SVG?
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Using canvas rather than SVG would require implementing a scenegraph, hit-testing,
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event dispatch, animation, and other features provided natively by SVG. All that is
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a significant amount of work, would have meant a longer time for the initial release
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of iD, and would likely increase the ongoing costs of maintenence and new features.
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On the other hand, SVG is already fast enough in many or most hardware/browser/OS/editing
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region combinations, and will only get faster as hardware improves and browser vendors
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optimize their implementations and take better advantage of hardware acceleration.
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In other words, the decision to use SVG rather than canvas was a classic performance
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vs. implementation cost tradeoff with strong arguments for trading off performance to
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reduce implementation costs.
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## Can I use iD offline?
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iD does not currently have an offline mode.
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To support offline usage requires caching or providing an offline proxy for the three
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main things iD uses the network for:
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* Downloading existing data -- this is done on demand as you pan around
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* Downloading tiles -- ditto
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* Uploading changes
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We've though a little about [caching tiles](https://github.com/systemed/iD/issues/127)
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and downloaded data, but haven't actively worked on it, nor on the data download/upload
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question.
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