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POHow to draw a polygon around a polyline in JavaScript?
 

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  1. POHow to draw a polygon around a polyline in JavaScript?
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    <p>I want to draw a polygon around a polyline. The polyline in my case is a Google Maps direction and I need to show a polygon around it within the Google Maps canvas.</p> <p><strong>First:</strong></p> <p>For offsetting I use the JavaScript Clipper Library. I have the following polyline (route): I make an offset polygon below using Clipper:</p> <p>I have a working <a href="http://jsbin.com/oVIcowo/1" rel="noreferrer">JS Bin example</a>.</p> <p>The code is:</p> <pre><code>&lt;html&gt; &lt;head&gt; &lt;title&gt;Javascript Clipper Library / Offset polyline&lt;/title&gt; &lt;script src="clipper.js"&gt;&lt;/script&gt; &lt;script&gt; function draw() { var polygons = [[{"X":72,"Y":59.45},{"X":136,"Y":66},{"X":170,"Y":99},{"X":171,"Y":114},{"X":183,"Y":125},{"X":218,"Y":144},{"X":218,"Y":165},{"X":226,"Y":193},{"X":254,"Y":195},{"X":283,"Y":195},{"X":292,"Y":202},{"X":325,"Y":213},{"X":341,"Y":234},{"X":397,"Y":245},{"X":417,"Y":248}]]; var scale = 100; reverse_copy(polygons); polygons = scaleup(polygons, scale); var cpr = new ClipperLib.Clipper(); var delta = 25; var joinType = ClipperLib.JoinType.jtRound; var miterLimit = 2; var AutoFix = true; var svg, offsetted_polygon, cont = document.getElementById('svgcontainer'); offsetted_polygon = cpr.OffsetPolygons(polygons, delta * scale, joinType, miterLimit, AutoFix); //console.log(JSON.stringify(offsetted_polygon)); // Draw red offset polygon svg = '&lt;svg style="margin-top:10px;margin-right:10px;margin-bottom:10px;background-color:#dddddd" width="540" height="340"&gt;'; svg += '&lt;path stroke="red" fill="red" stroke-width="2" stroke-opacity="0.6" fill-opacity="0.2" d="' + polys2path(offsetted_polygon, scale) + '"/&gt;'; //Draw blue polyline svg += '&lt;path stroke="blue" stroke-width="3" d="' + polys2path(polygons, scale) + '"/&gt;'; svg += '&lt;/svg&gt;'; cont.innerHTML += svg; } // helper function to scale up polygon coordinates function scaleup(poly, scale) { var i, j; if (!scale) scale = 1; for(i = 0; i &lt; poly.length; i++) { for(j = 0; j &lt; poly[i].length; j++) { poly[i][j].X *= scale; poly[i][j].Y *= scale; } } return poly; } // converts polygons to SVG path string function polys2path (poly, scale) { var path = "", i, j; if (!scale) scale = 1; for(i = 0; i &lt; poly.length; i++) { for(j = 0; j &lt; poly[i].length; j++) { if (!j) path += "M"; else path += "L"; path += (poly[i][j].X / scale) + ", " + (poly[i][j].Y / scale); } path += "Z"; } return path; } function reverse_copy(poly) { // Make reverse copy of polygons = convert polyline to a 'flat' polygon ... var k, klen = poly.length, len, j; for (k = 0; k &lt; klen; k++) { len = poly[k].length; poly[k].length = len * 2 - 2; for (j = 1; j &lt;= len - 2; j++) { poly[k][len - 1 + j] = { X: poly[k][len - 1 - j].X, Y: poly[k][len - 1 - j].Y } } } } &lt;/script&gt; &lt;/head&gt; &lt;body onload="draw()"&gt; &lt;h2&gt;Javascript Clipper Library / Offset polyline&lt;/h2&gt; This page shows an example of offsetting polyline and drawing it using SVG. &lt;div id="svgcontainer"&gt;&lt;/div&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p>And all this is good but now I must replace the polygon variables with points from Google Maps directions, so I do this change:</p> <pre><code>directionsService.route(request, function(response, status) { if (status == google.maps.DirectionsStatus.OK) { directionsDisplay.setDirections(response); function draw() { var polygons = response.routes[0].overview_path; //REST OF CODE } } } </code></pre> <p>I have a <a href="http://jsbin.com/uTATePe/9" rel="noreferrer">JS Bin example</a> with this code for offsetting the polygon around the polyline.</p> <p>But there is some problem, which I can't regonize and I can't get a polygon around directions.</p> <p>Is there any way to solve this problem?</p>
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    1. USSebastian Zartner
    1. USdr Code
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      1. POHow to draw a polygon around a polyline in JavaScript?
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      1. POHow to draw a polygon around a polyline in JavaScript?
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      1. POHow to draw a polygon around a polyline in JavaScript?
      1. USBytemain
      1. VTFavorite
    1. COwhy - minus for this question, what is wrong?
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      1. POHow to draw a polygon around a polyline in JavaScript?
      1. USdr Code
    2. COIt wasn't me who downvoted, but I can imagine it was because your question was too broad. S.O. isn't here to debug your programs. You need to show what steps you took to solve the problem yourself. For example, first step would be to tidy up your code and get rid of the javascript errors that are showing in the console. Then can you get it displaying the route (without the polygon)? Then try adding the polygon code.
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      1. POHow to draw a polygon around a polyline in JavaScript?
      1. USPaul LeBeau
    3. COyes,i try to solve my problem with var polygon=response.routes[0].overview_path;
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      1. POHow to draw a polygon around a polyline in JavaScript?
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