fix (map-generation, ui): avoid selecting invalid bboxes

- validate bbox and do not allow sending form if bbox crosses the antimeridian
- notify user with warning and display antimeridian if it is in the selected bbox

Refs: #279

client-src/base/base.css

@@ -81,12 +81,15 @@ body {
     display: inline-block;
 }
 
-.infobox {
+.infobox,
+.warningbox {
     position: relative;
     padding-left: 3.5rem;
+    margin: 0.5rem 0;
 }
 
-.infobox::before {
+.infobox::before,
+.warningbox::before {
     content: "i";
     position: absolute;
     width: 2rem;
@@ -101,6 +104,12 @@ body {
     top: calc(50% - 1rem);
 }
 
+.warningbox::before {
+    content: "!";
+    background-color: var(--heigit-red);
+    color: white;
+}
+
 .github-icon {
     display: inline-block;
     position: relative;

client-src/create/form.js

@@ -1,11 +1,9 @@
-import { PAPER_FORMAT, ORIENTATION, Margin } from "@giscience/ol-print-layout-control";
-import {
-    toLonLat, get as getProjection, transformExtent,
-} from "ol/proj";
+import { Margin, ORIENTATION, PAPER_FORMAT } from "@giscience/ol-print-layout-control";
+import { get as getProjection, toLonLat, transformExtent } from "ol/proj";
 import { SKETCH_MAP_MARGINS } from "./sketchMapMargins";
-import { fillSelectOptions, setDisabled } from "../shared";
+import { fillSelectOptions } from "../shared";
 
-function bindFormToPrintLayoutControl(printLayoutControl) {
+function bindFormToPrintLayoutControl(printLayoutControl, messageController) {
     const paperFormats = { ...PAPER_FORMAT };
     delete paperFormats.BROADSHEET;
 
@@ -81,15 +79,31 @@ function bindFormToPrintLayoutControl(printLayoutControl) {
     // disable form submit and display info if zoom is lower than 9
     function handleZoomChange(zoom) {
         if (zoom < 9) {
-            setDisabled("next-button", true);
-            document.querySelector("#infobox")
-                .classList
-                .remove("invisible");
+            messageController.addWarning("zoom-info");
         } else {
-            setDisabled("next-button", false);
-            document.querySelector("#infobox")
-                .classList
-                .add("invisible");
+            messageController.removeWarning("zoom-info");
+        }
+    }
+
+    function handleAntimeridian(bboxWgs84) {
+        // normalizeLon uses mathematic modulo like in R, not % symetric modulo like in Java
+        // or Javascript
+        const normalizeLon = (x) => ((((x + 180) % 360) + 360) % 360) - 180;
+
+        const antimeridianLayer = printLayoutControl.getMap()
+            .getLayers().getArray()
+            .find((l) => l.get("name") === "Antimeridian");
+
+        if (!bboxWgs84) return;
+        // check if antimeridian is within extent -> when left (x1) is bigger than right (x2)
+        const [left, , right] = bboxWgs84;
+
+        if (normalizeLon(left) > normalizeLon(right)) {
+            messageController.addWarning("antimeridian-info");
+            antimeridianLayer.setVisible(true);
+        } else {
+            messageController.removeWarning("antimeridian-info");
+            antimeridianLayer.setVisible(false);
         }
     }
 
@@ -98,6 +112,7 @@ function bindFormToPrintLayoutControl(printLayoutControl) {
         .getView();
     const initialZoom = view.getZoom();
     handleZoomChange(initialZoom);
+    handleAntimeridian(printLayoutControl.getBboxAsLonLat());
 
     // update form state on zoomchange
     printLayoutControl.getMap()
@@ -114,10 +129,12 @@ function bindFormToPrintLayoutControl(printLayoutControl) {
             document.querySelector("#page-setup-form").submit();
         });
 
-    // update the URL when the selection is changed  (e.g. to bookmark the current selection)
     printLayoutControl.on("change:bbox", (event) => {
+        // update the URL when the selection is changed  (e.g. to bookmark the current selection)
         const newCenter = printLayoutControl.getMap().getView().getCenter();
         window.history.replaceState({}, document.title, `?center=${newCenter}`);
+        // show warning and disable form if bbox crosses the antimeridian
+        handleAntimeridian(event.target.getBboxAsLonLat());
     });
 }
 

client-src/create/index.js

@@ -4,8 +4,9 @@ import "@kirtandesai/ol-geocoder/dist/ol-geocoder.css";
 import "./geocoder.css";
 import "./create.css";
 
-import { createMap, addPrintLayoutControl, addGeocoderControl } from "./map.js";
+import { addGeocoderControl, addPrintLayoutControl, createMap } from "./map.js";
 import { bindFormToPrintLayoutControl } from "./form.js";
+import { MessageController } from "./messageController";
 
 // Retrieve potentially given map center from URL (e.g. from a bookmarked selection)
 const searchParams = new URLSearchParams(window.location.search);
@@ -20,5 +21,7 @@ if (centerArg != null) {
 const map = createMap("map", center, 15);
 
 const printLayoutControl = addPrintLayoutControl(map);
-bindFormToPrintLayoutControl(printLayoutControl);
+const messageController = new MessageController();
+
+bindFormToPrintLayoutControl(printLayoutControl, messageController);
 addGeocoderControl(map);

client-src/create/map.js

@@ -1,10 +1,53 @@
-import { Map, View } from "ol";
+import { Feature, Map, View } from "ol";
 import { Tile } from "ol/layer";
 import { OSM } from "ol/source";
 import Geocoder from "@kirtandesai/ol-geocoder";
 import { PrintLayout, PAPER_FORMAT, ORIENTATION } from "@giscience/ol-print-layout-control";
+import { fromLonLat } from "ol/proj";
+import { LineString } from "ol/geom";
+import VectorSource from "ol/source/Vector";
+import VectorLayer from "ol/layer/Vector";
+import {
+    Fill, Stroke, Style, Text,
+} from "ol/style";
 import { SKETCH_MAP_MARGINS } from "./sketchMapMargins.js";
 
+function createAntiMeridianLayer() {
+    // Create a LineString feature
+    const lineString = new LineString([
+        fromLonLat([180, -90]), // Start point just to the east of the antimeridian
+        fromLonLat([180, 90]), // End point just to the west of the antimeridian
+    ]);
+
+    // Create a vector source and add the LineString feature to it
+    const vectorSource = new VectorSource({
+        features: [new Feature({
+            geometry: lineString,
+        })],
+    });
+
+    // Create a vector layer and set the source
+    return new VectorLayer({
+        name: "Antimeridian",
+        source: vectorSource,
+        visible: false,
+        style: new Style({
+            stroke: new Stroke({
+                color: "red",
+                width: 3,
+            }),
+            text: new Text({
+                text: "Antimeridian",
+                placement: "line",
+                offsetY: -10,
+                fill: new Fill({ color: "red" }),
+                font: "20px sans-serif",
+                repeat: 200,
+            }),
+        }),
+    });
+}
+
 /**
  * Creates an OpenLayers Map to an element
  * @param {string} [target=map] - a div id where the map will be rendered
@@ -26,6 +69,7 @@ function createMap(target = "map", lonLat = [966253.1800856147, 6344703.99262965
             new Tile({
                 source: new OSM(),
             }),
+            createAntiMeridianLayer(),
         ],
     });
 

client-src/create/messageController.js

@@ -0,0 +1,28 @@
+import { setDisabled } from "../shared";
+
+export class MessageController {
+    constructor() {
+        this.activeMessageIds = new Set();
+    }
+
+    addWarning(elementId) {
+        if (this.activeMessageIds.has(elementId)) return;
+
+        setDisabled("next-button", true);
+        document.querySelector(`#${elementId}`)
+            .classList
+            .remove("hidden");
+
+        this.activeMessageIds.add(elementId);
+    }
+
+    removeWarning(elementId) {
+        this.activeMessageIds.delete(elementId);
+        document.querySelector(`#${elementId}`)
+            .classList
+            .add("hidden");
+        if (this.activeMessageIds.size === 0) {
+            setDisabled("next-button", false);
+        }
+    }
+}

sketch_map_tool/templates/create.html

@@ -26,9 +26,18 @@
 
             <div id="right">
                 <div class="sketchy h1 center-text">Page Setup</div>
-                <article id="infobox" class="infobox invisible">Your Area of Interest is too large!
-                    <br>Zoom further in to be able to create a Sketch Map.
-                </article>
+                <div id="message-container" class="" style="height: 11rem; overflow-y: scroll; padding: 1rem; ">
+                    <article id="zoom-info" class="infobox hidden">Your Area of Interest is too large!
+                        <br>Zoom further in to be able to create a Sketch Map.
+                    </article>
+                    <article id="antimeridian-info" class="infobox">You are currently trying to
+                        request a map that crosses the +/-180° <a href="https://en.wikipedia.org/wiki/180th_meridian" target="_blank">antimeridian</a>. This is currently not
+                        supported, please move the map such that your extent is either left or right of
+                        the antimeridian.
+                    </article>
+                </div>
+
+
                 <form id="page-setup-form" action="/create/results" method="post">
                     <label for="format">Paper Format</label>
                     <select id="format" name="format"></select>