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/* Copyright 2021 Ben Fuller
* Apache License, Version 2.0
* See LICENSE file for copyright and licence details.
*/
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
)
// MapboxDetails holds the basic credentials to generate mapbox content.
type MapboxDetails struct {
Uname string
Style string
Apikey string
Padding int
}
// MapboxStatic creates a static image of a map
// with markers represented by m
func MapboxStatic(m []Marker, fname string, mbox MapboxDetails) error {
baseURL := "https://api.mapbox.com/"
query := fmt.Sprintf("styles/v1/%s/%s/static/", mbox.Uname, mbox.Style)
// it is possible to define a bbox (which defines the field of view)
// in the format [minlng,minlat,maxlng,maxlat]
// rather than "auto" which fits the field of view to the markers on the map
// the field after auto is the dimensions of the png image
// the parameters at the end (after the ?) are the access_token (required)
// and padding (optional)
suffix := fmt.Sprintf("/auto/800x720?padding=%d&access_token=%s", mbox.Padding, mbox.Apikey)
var markersMapbox string
for _, mark := range m {
// don't plot places with no data
if mark.Lat == 0 && mark.Lng == 0 {
continue
}
markersMapbox += MarkerToMapbox(mark, "", "aa0500") + ","
}
// if there were none left after removing those at (0,0), return
if len(markersMapbox) == 0 {
return fmt.Errorf("no markers with non-zero location")
}
// remove the final comma
markersMapbox = markersMapbox[:len(markersMapbox)-1]
// make the request
imgP, err := http.Get(baseURL + query + markersMapbox + suffix)
if err != nil {
return err
}
defer imgP.Body.Close()
bytes, _ := ioutil.ReadAll(imgP.Body)
// save the image
f, err := os.Create(fname)
f.Write(bytes)
return err
}
// MarkerToMapbox takes a Marker which has a position,
// and optionally a label (a-z, 0-99, or a Makl icon) and color
// (if you don't want these, provide empty strings)
// and returns the correctly formatted marker for Mapbox
func MarkerToMapbox(m Marker, label string, color string) string {
if label != "" {
label = "-" + label
}
if color != "" {
color = "+" + color
}
return fmt.Sprintf("pin-s%s%s(%f,%f)", label, color, m.Lng, m.Lat)
}
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