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NAME

Imager::Bing::MapLayer - create a map layer for Bing Maps

SYNOPSIS

    my $layer = Imager::Bing::MapLayer->new(
      base_dir           => $dir,     # base directory (default '.')
      overwrite          => 1,        # overwrite existing (default)
      autosave           => 1,        # save on exit (default)
      in_memory          => 0,        # keep tiles in memory (default false)
      min_level          => 1,        # min zoom level (default)
      max_level          => 19,       # max zoom level (default)
      combine            => 'darken', # tile composition method (default)
    );

    # Plot polygons (e.g. geographic boundaries)

    $layer->polygon(
       points => $points,                  # listref to [ lat, lon ] points
       fill   => Imager::Fill->new( ... ), #
    );

    # Plot greyscale gradient circles for heatmaps

    $layer->radial_circle(
        r      => 100,              # radius in meters
        -min_r => 1,                # minimum pixel radius for any zoom level
        x      => $longitude,       # longitude (x = east-west)
        y      => $latitude,        # latitude  (y = north-south)
    );

    # Blur filter

    $layer->filter( type => 'gaussian', stddev => 1 );

    # Colourise greyscale heatmaps

    $layer->colourise();

DESCRIPTION

This module is a wrapper around the Imager::Draw module, which allows you to create Bing map layers using longitude and latitude coordinates.

The module will automatically map them to the appropriate points on tile files.

ATTRIBUTES

`base_dir`

The base directory to save tile files in.

`in_memory`

The timeout for how many seconds a tile is kept in memory.

When a tile is timed out, it is saved to disk after each Imager drawing operation, and reloaded if it is later needed.

`centroid_latitude`

This is the default latitude for translating points to pixels. Generally you don't need to worry about this.

`centroid_longitude`

This is the default longitude for translating points to pixels. Generally you don't need to worry about this.

`overwrite`

When true (default), existing tiles will be overwritten rather than edited.

Be wary of editing existing tiles, since antialiased lines and opaque fills will darken existing points rather than drawing over them.

`autosave`

When true (default), tiles will be automatically saved.

Alternatively, you can use the "save" method.

`combine`

The tile combination method. It defaults to darken.

`tile_class`

The base class used for tiles.

METHODS

`levels`

  my @levels = @{ $layer->levels };

This returns a reference to a list of Imager::Bing::MapLayer::Level objects.

`min_level`

The minimum zoom level to generate.

`max_level`

The maximum zoom level to generate.

`radial_circle`

    $layer->radial_circle(
        r      => $radius_in_meters,
        -min_r => $min_radius_in_pixels,
        x      => $longitude,
        y      => $latitude,
    );

This method plots "fuzzy" greyscale circles, which are intended to be used for heatmaps. The radius is scaled appropriately for each zoom level in the layer.

If -min_r is specified, then a circle will always be drawn with that minimum radius: this ensures that lower zoom levels will always have a point plotted.

`colourise`

    $layer->colourise();

The method colourises greyscale layers. It is intended to be used for heatmaps generated using the "radial_circle" method.

`filter`

    $layer->filter( type => 'gaussian', stddev => 1 );

This applies Imager::Filters to every tile on every zoom level of the layer.

Be aware that some filter effects may enhance the edges of tiles in each zoom level.