Snapping Tile Renderer User Defined Model

snap_tiles_example.py

from bokeh.plotting import figure, output_file, show
from bokeh.models.renderers import TileRenderer
from bokeh.tile_providers import STAMEN_TONER
from bokeh.models import Range1d

output_file('snap_tiles.html')

class SnappingTileRenderer(TileRenderer):
    __implementation__ = """
    _ = require "underscore"
    $ = require "jquery"
    Util = require "util/util"
    TileRenderer = require "renderer/tile/tile_renderer"

    class SnappingTileRendererView extends TileRenderer.View
      type: "SnappingTileRendererView"

      _set_data: () ->
        super
        @plot_view.$el.dblclick(@on_double_click)

      on_double_click: (e) =>
        extent = @get_extent()
        [xmin, ymin, xmax, ymax] = extent

        x_percent = .5
        y_percent = .5
        zoom_level = @mget('tile_source').get_closest_level_by_extent(extent, @map_frame.get('height'), @map_frame.get('width'))
        old_resolution = @mget('tile_source').get_resolution(zoom_level)
        
        center_x = xmin + (e.offsetX * old_resolution)
        center_y = ymax - (e.offsetY * old_resolution)
        
        if e.shiftKey
          zoom_level = zoom_level - 1
        else
          zoom_level = zoom_level + 1

        new_resolution = @mget('tile_source').get_resolution(zoom_level)
        new_xrange = new_resolution * @map_frame.get('width')
        new_yrange = new_resolution * @map_frame.get('height')
        nxmin = center_x - (x_percent * new_xrange)
        nymin = center_y - (y_percent * new_yrange)
        nxmax = nxmin + new_xrange
        nymax = nymin + new_yrange
        new_extent = @mget('tile_source').snap_to_zoom([nxmin, nymin, nxmax, nymax], @map_frame.get('height'), @map_frame.get('width'), zoom_level)
        @x_range.set('start', new_extent[0])
        @y_range.set('start', new_extent[1])
        @x_range.set('end', new_extent[2])
        @y_range.set('end', new_extent[3])

    class SnappingTileRenderer extends TileRenderer.Model
      default_view: SnappingTileRendererView
      type: 'SnappingTileRenderer'

    module.exports =
      Model: SnappingTileRenderer
      View: SnappingTileRendererView
    """

def create_plot():
    axis_range = [-20000000, 20000000]
    x_range = Range1d(*axis_range)
    y_range = Range1d(*axis_range)
    p = figure(tools='pan,wheel_zoom', x_range=x_range, y_range=y_range, plot_height=800, plot_width=800)
    p.axis.visible = False
    p.renderers.append(SnappingTileRenderer(tile_source=STAMEN_TONER))
    return p

p = create_plot()
show(p)