render_grid_test.py

import os
import mapnik
import json
import pytest

from .utilities import execution_path

@pytest.fixture(scope="module")
def setup():
    # All of the paths used are relative, if we run the tests
    # from another directory we need to chdir()
    os.chdir(execution_path('.'))
    yield

if mapnik.has_grid_renderer():
    def show_grids(name, g1, g2):
        g1_file = '/tmp/mapnik-%s-actual.json' % name
        with open(g1_file, 'w') as f:
            f.write(json.dumps(g1, sort_keys=True))
        g2_file = '/tmp/mapnik-%s-expected.json' % name
        with open(g2_file, 'w') as f:
            f.write(json.dumps(g2, sort_keys=True))
        val = 'JSON does not match  ->\n'
        if g1['grid'] != g2['grid']:
            val += ' X grid does not match\n'
        else:
            val += ' ✓ grid matches\n'
        if g1['data'].keys() != g2['data'].keys():
            val += ' X data does not match\n'
        else:
            val += ' ✓ data matches\n'
        if g1['keys'] != g2['keys']:
            val += ' X keys do not\n'
        else:
            val += ' ✓ keys match\n'
        val += '\n\t%s\n\t%s' % (g1_file, g2_file)
        return val

    def show_grids2(name, g1, g2):
        g2_expected = '../data/grids/mapnik-%s-actual.json' % name
        if not os.path.exists(g2_expected):
            # create test fixture based on actual results
            with open(g2_expected, 'a+') as f:
                f.write(json.dumps(g1, sort_keys=True))
            return
        g1_file = '/tmp/mapnik-%s-actual.json' % name
        with open(g1_file, 'w') as f:
            f.write(json.dumps(g1, sort_keys=True))
        val = 'JSON does not match  ->\n'
        if g1['grid'] != g2['grid']:
            val += ' X grid does not match\n'
        else:
            val += ' ✓ grid matches\n'
        if g1['data'].keys() != g2['data'].keys():
            val += ' X data does not match\n'
        else:
            val += ' ✓ data matches\n'
        if g1['keys'] != g2['keys']:
            val += ' X keys do not\n'
        else:
            val += ' ✓ keys match\n'
        val += '\n\t%s\n\t%s' % (g1_file, g2_expected)
        return val

    # previous rendering using agg ellipse directly
    grid_correct_new = {
        "data": {
            "North East": {
                "Name": "North East"},
            "North West": {
                "Name": "North West"},
            "South East": {
                "Name": "South East"},
            "South West": {
                "Name": "South West"}},
        "grid": [
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          !!                                  ##                ",
            "         !!!                                 ###                ",
            "          !!                                  ##                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          $$                                  %%                ",
            "         $$$                                  %%                ",
            "          $$                                  %%                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                "],
        "keys": [
            "",
            "North West",
            "North East",
            "South West",
            "South East"]}

    # newer rendering using svg
    grid_correct_new2 = {
        "data": {
            "North East": {
                "Name": "North East"},
            "North West": {
                "Name": "North West"},
            "South East": {
                "Name": "South East"},
            "South West": {
                "Name": "South West"}},
        "grid": [
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          !!                                  ##                ",
            "         !!!                                 ###                ",
            "          !!                                  ##                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          $$                                  %%                ",
            "         $$$                                  %%                ",
            "          $$                                  %%                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                "],
        "keys": [
            "",
            "North West",
            "North East",
            "South West",
            "South East"]}

    grid_correct_new3 = {
        "data": {
            "North East": {
                "Name": "North East"},
            "North West": {
                "Name": "North West"},
            "South East": {
                "Name": "South East"},
            "South West": {
                "Name": "South West"}},
        "grid": [
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          !!                                  ##                ",
            "         !!!                                 ###                ",
            "          !!                                  ##                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          $$                                  %%                ",
            "         $$$                                  %%                ",
            "          $                                   %%                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                "],
        "keys": [
            "",
            "North West",
            "North East",
            "South West",
            "South East"]}

    def resolve(grid, row, col):
        """ Resolve the attributes for a given pixel in a grid.
        """
        row = grid['grid'][row]
        utf_val = row[col]
        # http://docs.python.org/library/functions.html#ord
        codepoint = ord(utf_val)
        if (codepoint >= 93):
            codepoint -= 1
        if (codepoint >= 35):
            codepoint -= 1
        codepoint -= 32
        key = grid['keys'][codepoint]
        return grid['data'].get(key)

    def create_grid_map(width, height, sym):
        ds = mapnik.MemoryDatasource()
        context = mapnik.Context()
        context.push('Name')
        f = mapnik.Feature(context, 1)
        f['Name'] = 'South East'
        f.geometry = mapnik.Geometry.from_wkt('POINT (143.10 -38.60)')
        ds.add_feature(f)

        f = mapnik.Feature(context, 2)
        f['Name'] = 'South West'
        f.geometry = mapnik.Geometry.from_wkt('POINT (142.48 -38.60)')
        ds.add_feature(f)

        f = mapnik.Feature(context, 3)
        f['Name'] = 'North West'
        f.geometry = mapnik.Geometry.from_wkt('POINT (142.48 -38.38)')
        ds.add_feature(f)

        f = mapnik.Feature(context, 4)
        f['Name'] = 'North East'
        f.geometry = mapnik.Geometry.from_wkt('POINT (143.10 -38.38)')
        ds.add_feature(f)
        s = mapnik.Style()
        r = mapnik.Rule()
        sym.allow_overlap = True
        r.symbolizers.append(sym)
        s.rules.append(r)
        lyr = mapnik.Layer('Places')
        lyr.datasource = ds
        lyr.styles.append('places_labels')
        m = mapnik.Map(width, height)
        m.append_style('places_labels', s)
        m.layers.append(lyr)
        return m

    def test_render_grid(setup):
        """ test render_grid method"""
        width, height = 256, 256
        sym = mapnik.MarkersSymbolizer()
        sym.width = mapnik.Expression('10')
        sym.height = mapnik.Expression('10')
        m = create_grid_map(width, height, sym)
        ul_lonlat = mapnik.Coord(142.30, -38.20)
        lr_lonlat = mapnik.Coord(143.40, -38.80)
        m.zoom_to_box(mapnik.Box2d(ul_lonlat, lr_lonlat))

        # new method
        grid = mapnik.Grid(m.width, m.height, key='Name')
        mapnik.render_layer(m, grid, layer=0, fields=['Name'])
        utf1 = grid.encode('utf', resolution=4)
        assert utf1 == grid_correct_new3, show_grids('new-markers', utf1, grid_correct_new3)

        # check a full view is the same as a full image
        grid_view = grid.view(0, 0, width, height)
        # for kicks check at full res too
        utf3 = grid.encode('utf', resolution=1)
        utf4 = grid_view.encode('utf', resolution=1)
        assert utf3['grid'] ==  utf4['grid']
        assert utf3['keys'] ==  utf4['keys']
        assert utf3['data'] ==  utf4['data']

        assert resolve(utf4, 0, 0) ==  None

        # resolve some center points in the
        # resampled view
        utf5 = grid_view.encode('utf', resolution=4)
        assert resolve(utf5, 25, 10) ==  {"Name": "North West"}
        assert resolve(utf5, 25, 46) ==  {"Name": "North East"}
        assert resolve(utf5, 38, 10) ==  {"Name": "South West"}
        assert resolve(utf5, 38, 46) ==  {"Name": "South East"}

    grid_feat_id = {
        'keys': [
            '',
            '3',
            '4',
            '2',
            '1'],
        'data': {
            '1': {
                'Name': 'South East'},
            '3': {
                'Name': u'North West'},
            '2': {
                'Name': 'South West'},
            '4': {
                'Name': 'North East'}},
        'grid': [
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '          !!                                  ##                ',
            '         !!!                                 ###                ',
            '          !!                                  ##                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '         $$$                                  %%                ',
            '         $$$                                 %%%                ',
            '          $$                                  %%                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ',
            '                                                                ']}

    grid_feat_id2 = {
        "data": {
            "1": {
                "Name": "South East"},
            "2": {
                "Name": "South West"},
            "3": {
                "Name": "North West"},
            "4": {
                "Name": "North East"}},
        "grid": [
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          !!                                  ##                ",
            "         !!!                                 ###                ",
            "          !!                                  ##                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          $$                                  %%                ",
            "         $$$                                  %%                ",
            "          $$                                  %%                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                "],
        "keys": [
            "",
            "3",
            "4",
            "2",
            "1"]}

    grid_feat_id3 = {
        "data": {
            "1": {
                "Name": "South East",
                "__id__": 1},
            "2": {
                "Name": "South West",
                "__id__": 2},
            "3": {
                "Name": "North West",
                "__id__": 3},
            "4": {
                "Name": "North East",
                "__id__": 4}},
        "grid": [
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          !!                                  ##                ",
            "         !!!                                 ###                ",
            "          !!                                  ##                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "          $$                                  %%                ",
            "         $$$                                  %%                ",
            "          $                                   %%                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                "],
        "keys": [
            "",
            "3",
            "4",
            "2",
            "1"]}

    def test_render_grid3():
        """ test using feature id"""
        width, height = 256, 256
        sym = mapnik.MarkersSymbolizer()
        sym.width = mapnik.Expression('10')
        sym.height = mapnik.Expression('10')
        m = create_grid_map(width, height, sym)
        ul_lonlat = mapnik.Coord(142.30, -38.20)
        lr_lonlat = mapnik.Coord(143.40, -38.80)
        m.zoom_to_box(mapnik.Box2d(ul_lonlat, lr_lonlat))

        grid = mapnik.Grid(m.width, m.height, key='__id__')
        mapnik.render_layer(m, grid, layer=0, fields=['__id__', 'Name'])
        utf1 = grid.encode('utf', resolution=4)
        assert utf1 == grid_feat_id3, show_grids('id-markers', utf1 ==  grid_feat_id3)
        # check a full view is the same as a full image
        grid_view = grid.view(0, 0, width, height)
        # for kicks check at full res too
        utf3 = grid.encode('utf', resolution=1)
        utf4 = grid_view.encode('utf', resolution=1)
        assert utf3['grid'] ==  utf4['grid']
        assert utf3['keys'] ==  utf4['keys']
        assert utf3['data'] ==  utf4['data']

        assert resolve(utf4, 0, 0) ==  None

        # resolve some center points in the
        # resampled view
        utf5 = grid_view.encode('utf', resolution=4)
        assert resolve(utf5, 25, 10) == {"Name": "North West", "__id__": 3}
        assert resolve(utf5, 25, 46) == {"Name": "North East", "__id__": 4}
        assert resolve(utf5, 38, 10) == {"Name": "South West", "__id__": 2}
        assert resolve(utf5, 38, 46) == {"Name": "South East", "__id__": 1}

    def gen_grid_for_id(pixel_key):
        ds = mapnik.MemoryDatasource()
        context = mapnik.Context()
        context.push('Name')
        f = mapnik.Feature(context, pixel_key)
        f['Name'] = str(pixel_key)
        f.geometry = mapnik.Geometry.from_wkt(
            'POLYGON ((0 0, 0 256, 256 256, 256 0, 0 0))')
        ds.add_feature(f)
        s = mapnik.Style()
        r = mapnik.Rule()
        symb = mapnik.PolygonSymbolizer()
        r.symbolizers.append(symb)
        s.rules.append(r)
        lyr = mapnik.Layer('Places')
        lyr.datasource = ds
        lyr.styles.append('places_labels')
        width, height = 256, 256
        m = mapnik.Map(width, height)
        m.append_style('places_labels', s)
        m.layers.append(lyr)
        m.zoom_all()
        grid = mapnik.Grid(m.width, m.height, key='__id__')
        mapnik.render_layer(m, grid, layer=0, fields=['__id__', 'Name'])
        return grid

    def test_negative_id():
        grid = gen_grid_for_id(-1)
        assert grid.get_pixel(128, 128) ==  -1
        utf1 = grid.encode('utf', resolution=4)
        assert utf1['keys'] ==  ['-1']

    def test_32bit_int_id():
        int32 = 2147483647
        grid = gen_grid_for_id(int32)
        assert grid.get_pixel(128, 128) ==  int32
        utf1 = grid.encode('utf', resolution=4)
        assert utf1['keys'] ==  [str(int32)]
        max_neg = -(int32)
        grid = gen_grid_for_id(max_neg)
        assert grid.get_pixel(128, 128) ==  max_neg
        utf1 = grid.encode('utf', resolution=4)
        assert utf1['keys'] ==  [str(max_neg)]

    def test_64bit_int_id():
        int64 = 0x7FFFFFFFFFFFFFFF
        grid = gen_grid_for_id(int64)
        assert grid.get_pixel(128, 128) ==  int64
        utf1 = grid.encode('utf', resolution=4)
        assert utf1['keys'] ==  [str(int64)]
        max_neg = -(int64)
        grid = gen_grid_for_id(max_neg)
        assert grid.get_pixel(128, 128) ==  max_neg
        utf1 = grid.encode('utf', resolution=4)
        assert utf1['keys'] ==  [str(max_neg)]

    def test_id_zero():
        grid = gen_grid_for_id(0)
        assert grid.get_pixel(128, 128) ==  0
        utf1 = grid.encode('utf', resolution=4)
        assert utf1['keys'] ==  ['0']

    line_expected = {
        "keys": [
            "",
            "1"],
        "data": {
            "1": {
                "Name": "1"}},
        "grid": [
            "                                                               !",
            "                                                            !!  ",
            "                                                         !!     ",
            "                                                      !!        ",
            "                                                   !!           ",
            "                                                !!              ",
            "                                             !!                 ",
            "                                          !!                    ",
            "                                       !!                       ",
            "                                    !!                          ",
            "                                 !!                             ",
            "                              !!                                ",
            "                           !!                                   ",
            "                        !!                                      ",
            "                     !!                                         ",
            "                  !!                                            ",
            "               !!                                               ",
            "            !!                                                  ",
            "         !!                                                     ",
            "      !!                                                        ",
            "   !!                                                           ",
            "!!                                                              ",
            " !                                                              ",
            "  !                                                             ",
            "   !                                                            ",
            "    !                                                           ",
            "     !                                                          ",
            "      !                                                         ",
            "       !                                                        ",
            "        !                                                       ",
            "         !                                                      ",
            "          !                                                     ",
            "           !                                                    ",
            "            !                                                   ",
            "             !                                                  ",
            "              !                                                 ",
            "               !                                                ",
            "                !                                               ",
            "                 !                                              ",
            "                  !                                             ",
            "                   !                                            ",
            "                    !                                           ",
            "                     !                                          ",
            "                      !                                         ",
            "                       !                                        ",
            "                        !                                       ",
            "                         !                                      ",
            "                          !                                     ",
            "                           !                                    ",
            "                            !                                   ",
            "                             !                                  ",
            "                              !                                 ",
            "                               !                                ",
            "                                !                               ",
            "                                 !                              ",
            "                                  !                             ",
            "                                   !                            ",
            "                                    !                           ",
            "                                     !                          ",
            "                                      !                         ",
            "                                       !                        ",
            "                                        !                       ",
            "                                         !                      ",
            "                                          !                     "]}

    def test_line_rendering():
        ds = mapnik.MemoryDatasource()
        context = mapnik.Context()
        context.push('Name')
        pixel_key = 1
        f = mapnik.Feature(context, pixel_key)
        f['Name'] = str(pixel_key)
        f.geometry = mapnik.Geometry.from_wkt(
            'LINESTRING (30 10, 10 30, 40 40)')
        ds.add_feature(f)
        s = mapnik.Style()
        r = mapnik.Rule()
        symb = mapnik.LineSymbolizer()
        r.symbolizers.append(symb)
        s.rules.append(r)
        lyr = mapnik.Layer('Places')
        lyr.datasource = ds
        lyr.styles.append('places_labels')
        width, height = 256, 256
        m = mapnik.Map(width, height)
        m.append_style('places_labels', s)
        m.layers.append(lyr)
        m.zoom_all()
        # mapnik.render_to_file(m,'test.png')
        grid = mapnik.Grid(m.width, m.height, key='__id__')
        mapnik.render_layer(m, grid, layer=0, fields=['Name'])
        utf1 = grid.encode()
        assert utf1 == line_expected, show_grids('line', utf1, line_expected)

    point_expected = {
        "data": {
            "1": {
                "Name": "South East"},
            "2": {
                "Name": "South West"},
            "3": {
                "Name": "North West"},
            "4": {
                "Name": "North East"}},
        "grid": [
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "         !!!!                                ####               ",
            "         !!!!                                ####               ",
            "         !!!!                                ####               ",
            "         !!!!                                ####               ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "         $$$$                                %%%%               ",
            "         $$$$                                %%%%               ",
            "         $$$$                                %%%%               ",
            "         $$$$                                %%%%               ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                ",
            "                                                                "],
        "keys": [
            "",
            "3",
            "4",
            "2",
            "1"]}

    def test_point_symbolizer_grid():
        width, height = 256, 256
        sym = mapnik.PointSymbolizer()
        sym.file = '../data/images/dummy.png'
        m = create_grid_map(width, height, sym)
        ul_lonlat = mapnik.Coord(142.30, -38.20)
        lr_lonlat = mapnik.Coord(143.40, -38.80)
        m.zoom_to_box(mapnik.Box2d(ul_lonlat, lr_lonlat))
        grid = mapnik.Grid(m.width, m.height)
        mapnik.render_layer(m, grid, layer=0, fields=['Name'])
        utf1 = grid.encode()
        assert utf1 == point_expected, show_grids('point-sym', utf1, point_expected)

    test_point_symbolizer_grid.requires_data = True

    # should throw because this is a mis-usage
    # https://github.com/mapnik/mapnik/issues/1325
    def test_render_to_grid_multiple_times():
        with pytest.raises(RuntimeError):
            # create map with two layers
            m = mapnik.Map(256, 256)
            s = mapnik.Style()
            r = mapnik.Rule()
            sym = mapnik.MarkersSymbolizer()
            sym.allow_overlap = True
            r.symbolizers.append(sym)
            s.rules.append(r)
            m.append_style('points', s)

            # NOTE: we use a csv datasource here
            # because the memorydatasource fails silently for
            # queries requesting fields that do not exist in the datasource
            ds1 = mapnik.Datasource(**{"type": "csv", "inline": '''
            wkt,Name
            "POINT (143.10 -38.60)",South East'''})
            lyr1 = mapnik.Layer('One')
            lyr1.datasource = ds1
            lyr1.styles.append('points')
            m.layers.append(lyr1)

            ds2 = mapnik.Datasource(**{"type": "csv", "inline": '''
            wkt,Value
            "POINT (142.48 -38.60)",South West'''})
            lyr2 = mapnik.Layer('Two')
            lyr2.datasource = ds2
            lyr2.styles.append('points')
            m.layers.append(lyr2)

            ul_lonlat = mapnik.Coord(142.30, -38.20)
            lr_lonlat = mapnik.Coord(143.40, -38.80)
            m.zoom_to_box(mapnik.Box2d(ul_lonlat, lr_lonlat))
            grid = mapnik.Grid(m.width, m.height)
            mapnik.render_layer(m, grid, layer=0, fields=['Name'])
            # should throw right here since Name will be a property now on the `grid` object
            # and it is not found on the second layer
            mapnik.render_layer(m, grid, layer=1, fields=['Value'])
            grid.encode()