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42 lines
2.3 KiB
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42 lines
2.3 KiB
Plaintext
/*! \page api_break Backwards Incompatible Changes
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\tableofcontents
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The API of QGIS libraries is allowed to be changed just between major versions of QGIS. For example, there
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are various planned backwards incompatible changes between QGIS 1.8 and 2.0 because the version 2.0 is a new
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major version. After a release of a major version of QGIS (e.g. 2.0) the developer team is committed to maintain
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stable API for all subsequent minor releases (2.2, 2.4, ...). That roughly means we do not rename classes and methods,
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remove them nor change their semantics. Existing code should keep working when the user updates QGIS
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to another minor version (e.g. from 2.0 to 2.2), so all extensions of existing classes should be done in a manner that
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third party developers do not need to adjust their code to work properly with newer QGIS releases.
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Sometimes, however, we may need to break the API as a result of some code changes. These cases should be only exceptions
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and they should happen only after consideration and agreement of the development team. Backwards incompatible changes
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with too big impact should be deferred to a major version release.
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This page tries to maintain a list with incompatible changes that happened in previous releases.
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\section qgis_api_break_2_4 QGIS 2.4
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\subsection qgis_api_break_mtr Multi-threaded Rendering
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<ul>
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<li>QgsMapCanvas::refresh() only schedules a map refresh (in near feature) and returns immediately - before it would do the drawing immediately
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and return when the map is redrawn. A call to refresh() will have no effect if there is already a scheduled pending refresh.
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When map canvas does actual rendering, it will first emit renderStarting() signal, once done it will emit mapCanvasRefreshed().
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The client code doing refresh() in order to later save map image should be updated to use new QgsMapRendererJob API which is better suited for such task.
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<li>QgsPluginLayer::draw() is now run in a background thread. It is recommended to implement newly added QgsPluginLayer::createMapRenderer()
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method instead of using QgsPluginLayer::draw().
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</ul>
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\section qgis_api_break_2_6 QGIS 2.6
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\subsection qgis_api_break_legend_refactoring Legend Refactoring
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<ul>
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<li>QgsComposerLegend::model() - not being used anymore. The model was replaced by one based on QgsLayerTreeModel class
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and is available in QgsComposerLegend::modelV2()
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</ul>
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*/
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