2018-10-29 00:07:56 +01:00
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# QtPBFImagePlugin
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2018-10-29 01:04:26 +01:00
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Qt image plugin for displaying Mapbox vector tiles
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## Description
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QtPBFImagePlugin is a Qt image plugin that enables applications capable of
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displaying raster MBTiles maps to also display vector (PBF) tiles without
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(almost, see usage) any application modifications.
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Standard Mapbox GL Styles are used for styling the maps. Most style features
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used by [Maputnik](http://editor.openmaptiles.org) are supported. The style
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is loaded from /usr/share/pbf/style.json or ~/.pbf/style.json if it exists.
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## Usage
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Due to a major design flaw in the Mapbox vector tiles specification (the zoom
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is not part of the PBF data), the plugin can not be used "as is", but passing
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the zoom level is necessary. This is done by exploiting the optional format
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parameter of the QImage constructor or the QImage::fromData() or
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QPixmap::loadFromData() functions. The zoom number is passed as ASCII string
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to the functions:
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```cpp
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QPixmap pm;
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pm.loadFromData(tileData(_zoom), QString::number(_zoom).toLatin1());
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```
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## Build
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Build requirements:
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* QT 5.x
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* Google Protocol Buffers (protobuf-lite)
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Build steps:
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```shell
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qmake gpxsee.pro
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make
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```
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## Install
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Copy the plugin to the system Qt image plugins path to make it work. You may
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also set the QT_PLUGIN_PATH system variable before starting the application.
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## Limitations
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As the plugin only has isolated info about a single tile image, texts
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overlapping to neighbour tiles can not be displayed or their overlapping can
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not be avoided (the plugin uses the first approach). This is a principal
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constraint that can't be evaded.
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