renderAll.js

'use strict';

const buildConfig = require('./lib/buildConfig')();

const fs = require('fs');
const path = require('path');

const mapnik = require('mapnik');

const execSync = require('child_process').execSync;

const TILESIZE = 512;

const merc = new mapnik.Projection('+init=epsg:3857');

// register fonts and datasource plugins
mapnik.register_default_fonts();
mapnik.register_default_input_plugins();

// Add some padding around a highlighted feature
// extent coords are in the form [minx, miny, maxx, maxy]
// or, roughly, (lower-left, top-right)
const padExtent = function(extent) {
  const xdiff = extent[2] - extent[0];
  const ydiff = extent[3] - extent[1];
  return [
    extent[0] - xdiff * 0.1,
    extent[1] - ydiff * 0.1,
    extent[2] + xdiff * 0.1,
    extent[3] + ydiff * 0.1
  ];
};

const renderTile = function(tile) {
  // skip rendering tiles without an OCDID, as they won't be visible
  // in the product and this avoids rendering ~10K tiles
  if (tile.ocdid === undefined) {
    return;
  }

  console.log('Rendering ' + tile.xmlPath);

  const map = new mapnik.Map(TILESIZE, TILESIZE);
  const xmlPath = tile.xmlPath;
  let outPath = path.normalize(path.join(xmlPath, '..', path.basename(xmlPath, '.xml') + '.png'));
  map.fromStringSync(fs.readFileSync(xmlPath).toString());

  let extent = tile.extent;
  extent = padExtent(extent);    // add padding around highlighted feature
  extent = merc.forward(extent); // convert to Web Mercator coords
  map.zoomToBox(extent);

  map.renderFileSync(outPath);

  outPath = buildConfig.moveToOCDID(outPath, tile.ocdid, tile.level);

  // apply 'water' background color
  execSync(
    `gm convert ${outPath} -background '#d3ddff' -extent 0x0 ${outPath}`,
    function(error, stdout, stderr) {
      if (error !== undefined) {
        console.log(`Failed to set background on ${outPath}`);
        console.log(error);
        console.log(stderr);
      }
    }
  );
};
exports.renderTile = renderTile;

exports.renderAll = function(filterOcdid) {
  const tiles = JSON.parse(fs.readFileSync('build/tiles.json'));
  tiles.forEach(function(tile) {
    if (filterOcdid && tile.ocdid && tile.ocdid.indexOf(filterOcdid) !== -1) {
      return;
    }

    renderTile(tile);
  });
};