Changing selection color in exporting ArcMap layout with ArcPy

use_custom_selection_color_arcpy.py

'''
Script that demonstrates how to use predefined layer files (.lyr)
to change the selection symbol for any map document layer. The
selection symbol is not exposed via `arcpy.mapping.Layer` object, so
it is necessary to emulate the selection using another layer drawn
on top of the layer that you targeting your selection against.

The script assumes that you have prepared beforehand 3 layers (.lyr
files) for each shape type (point, polyline, polygon).
'''

import arcpy
import arcpy.mapping as mp


#----------------------------------------------------------------------
def get_layer_shape_type(mxd, layer_name):
    """return shape type of layer in the operational map document"""
    lyr = mp.ListLayers(mxd, layer_name)[0]
    return arcpy.Describe(lyr).shapeType.lower()


#----------------------------------------------------------------------
def main():
    # name of the layer that will have selections
    base_layer_name = 'cities'

    # name of the layer that will be drawn on top emulating the selection symbol
    select_layer_name = base_layer_name + '_selection'

    mxd = arcpy.mapping.MapDocument(r'C:\GIS\Temp\export_selection.mxd')
    df = mp.ListDataFrames(mxd)[0]

    # get the right layer based on shape type of the base layer
    lyr_template = arcpy.mapping.Layer(r'C:\GIS\Temp\{}.lyr'.format(
        get_layer_shape_type(mxd, base_layer_name)))

    # copy the TOC layer that will have selections to the top of TOC
    arcpy.mapping.AddLayer(df, mp.ListLayers(mxd, base_layer_name)[0], 'TOP')

    # rename the newly copied layer
    mp.ListLayers(mxd, base_layer_name)[0].name = select_layer_name

    # update the symbology of the newly copied layer to have the needed
    # selection symbol
    mp.UpdateLayer(
        df,
        mp.ListLayers(mxd, select_layer_name)[0],
        lyr_template,
        symbology_only=True)

    print mp.ListLayers(mxd)
    # [<map layer u'cities_selected'>, <map layer u'cities'>]

    lyr_base = mp.ListLayers(mxd, base_layer_name)[0]
    lyr_selection = mp.ListLayers(mxd, select_layer_name)[0]

    # doing selection on the base layer
    arcpy.SelectLayerByAttribute_management(
        in_layer_or_view=lyr_base,
        selection_type='NEW_SELECTION',
        where_clause=" STATE_NAME = 'Oregon' ")
    df.zoomToSelectedFeatures()

    print lyr_base.getSelectionSet()
    #[3129L, 3130L, 3131L, 3132L]

    # limiting the features to be drawn in the layer with selection symbol
    lyr_selection.definitionQuery = "OBJECTID in ({})".format(
        ','.join([str(i) for i in lyr_base.getSelectionSet()]))

    # clearing selection of the base layer
    arcpy.SelectLayerByAttribute_management(
        in_layer_or_view=lyr_base, selection_type='CLEAR_SELECTION')

    # exporting the map
    arcpy.RefreshActiveView()
    mp.ExportToPNG(mxd, r'C:\GIS\Temp\sel_prog_{}.png'.format(base_layer_name))


main()