在Mapnk中使用XML定义图像文件填充多边形

 <Map background-color="#efefef" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <Style name="My Style">
        <Rule>
            <PolygonSymbolizer fill="#ffffff"/>
            <LineSymbolizer stroke="rgb(50%,50%,50%)" stroke-width="1" stroke-dasharray="8,20"/>
            <PolygonPatternSymbolizer width="6" height="6" type="png" file="/gdata/sym_line45.png"/>
        </Rule>
    </Style>
    <Layer name="world" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
        <StyleName>My Style</StyleName>
        <Datasource>
            <Parameter name="type">shape</Parameter>
            <Parameter name="file">/gdata/fig_data/fig_data_poly.shp</Parameter>
        </Datasource>
    </Layer>
</Map>