Test case for Mapnik's Bug #2084

README.md

Test case for Mapnik's Bug #2084

Based on https://gist.github.com/springmeyer/7459452

Depends

• Mapnik >= 2.3 and the python bindings

How to replicate

To replicate the bug run:

python render.py

You need to change the style in map.xml and the output file in render.py:

point.png is the reference image

shield1.png has dy=0 and the point is in the same place as point.png

shield2.png has dy=-10 and the point has moved some pixels up

shield3.png has dy=-30 and the point has moved the same pixels up as with dy=-10

I expect the point to always be in the same position

blue_point_8.png

map.xml

<Map
    background-color="#eee"
    srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">

    <!-- polygon to frame the map testcase to m.zoom_all sets reasonable extents -->

    <Style name="frame">
        <Rule>
            <PolygonSymbolizer />
        </Rule>
    </Style>

    <Layer name="frame" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
        <StyleName>frame</StyleName>
        <Datasource>
            <Parameter name="type">csv</Parameter>
            <Parameter name="inline">
wkt|name
Polygon((-180.0 -85.0, -180.0 85.0, 180.0 85.0, 180.0 -85.0, -180.0 -85.0))|bounds
            </Parameter>
        </Datasource>
    </Layer>

    <!-- let's pretend the below exhibits some bug -->

    <Style name="point">
        <Rule>
            <MarkersSymbolizer />
        </Rule>
    </Style>

    <Style name="shield1">
        <Rule>
            <ShieldSymbolizer face-name="DejaVu Sans Book"
            placement="point"
            file="blue_point_8.png" >"test"</ShieldSymbolizer>
        </Rule>
    </Style>

    <Style name="shield2">
        <Rule>
            <ShieldSymbolizer face-name="DejaVu Sans Book"
            file="blue_point_8.png" dy="-10">"test"</ShieldSymbolizer>
        </Rule>
    </Style>

    <Style name="shield3">
        <Rule>
            <ShieldSymbolizer face-name="DejaVu Sans Book"
            file="blue_point_8.png" dy="-30">"test"</ShieldSymbolizer>
        </Rule>
    </Style>

    <Layer name="layer" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
        <StyleName>shield3</StyleName>
        <Datasource>
            <Parameter name="type">csv</Parameter>
            <Parameter name="inline">
id|name|wkt
1|null island|Point(0 0)
            </Parameter>
        </Datasource>
    </Layer>
</Map>

point.png

render.py

import mapnik
m = mapnik.Map(256,256)
mapnik.load_map(m,'map.xml')
m.zoom_all()
im = mapnik.Image(m.width,m.height)
mapnik.render(m,im)
im.save('shield3.png')

shield1.png

shield2.png

shield3.png