地図上にテキストを書き込む方法～OpenLayersで図形を描画する②

前回の記事ではOpenLayersで図形描画の基本についてお伝えしました。

これでOpenLayersがお絵かきアプリに早変わりします。

今回はさらに深堀りしていきます。
OpenLayersの描画機能では以下のことができます。

今回は「テキストを書き込む」についてお伝えいたします。

1 実際にやってみた
- 1.1 矩形描画
- 1.2 テキスト描画
2 解説
3 まとめ

実際にやってみた

まずは結果から、触ってみてください↓↓↓

ソースコードは以下になります。

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/openlayers/4.6.5/ol.css" integrity="sha256-rQq4Fxpq3LlPQ8yP11i6Z2lAo82b6ACDgd35CKyNEBw=" crossorigin="anonymous" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/openlayers/4.6.5/ol.js" integrity="sha256-77IKwU93jwIX7zmgEBfYGHcmeO0Fx2MoWB/ooh9QkBA=" crossorigin="anonymous"></script>
    <script src="https://code.jquery.com/jquery-2.2.3.min.js"></script>
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css" integrity="sha384-HSMxcRTRxnN+Bdg0JdbxYKrThecOKuH5zCYotlSAcp1+c8xmyTe9GYg1l9a69psu" crossorigin="anonymous">

<!-- Optional theme -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap-theme.min.css" integrity="sha384-6pzBo3FDv/PJ8r2KRkGHifhEocL+1X2rVCTTkUfGk7/0pbek5mMa1upzvWbrUbOZ" crossorigin="anonymous">

<!-- Latest compiled and minified JavaScript -->
<script src="https://stackpath.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js" integrity="sha384-aJ21OjlMXNL5UyIl/XNwTMqvzeRMZH2w8c5cRVpzpU8Y5bApTppSuUkhZXN0VxHd" crossorigin="anonymous"></script>
  </head>
  <body>
    <div id="map" style="height:300px"></div>
    <div id="popup"></div>
    <script>
    
      // 描画された図形に適用されるスタイル
      var styleFunction = function(feature) {
        var geometry = feature.getGeometry();
        var shape = feature.get('shape');
        var styles = [];
        if (geometry.getType() == 'Point') {
          // 点の場合、マーカー配置
          styles.push(new ol.style.Style({
            image: new ol.style.Icon ({
                anchor: [0.5, 46],
                anchorXUnits: 'fraction',
                anchorYUnits: 'pixels',
                opacity: 0.95,
                src: 'https://openlayers.org/en/latest/examples/data/icon.png'
            })
          }));
        } else if (geometry.getType() == 'LineString'){
          styles.push(new ol.style.Style({
            stroke: new ol.style.Stroke({
              color: '#ff0000',
              width: 2
            })
          }));
        } else if (shape == 'Text') {
          var extent = ol.extent.boundingExtent(geometry.getCoordinates()[0]);
          
          var center = [(extent[2] - extent[0]) / 2 + extent[0], (extent[3] - extent[1]) / 2 + extent[1]];
          var centerPixel = map.getPixelFromCoordinate(center);
          var leftTopPixel = map.getPixelFromCoordinate([extent[0], extent[1]]);
          styles.push(new ol.style.Style({
            stroke: new ol.style.Stroke({
              color: 'rgba(0,0,0,0)',
              width: 1
            }),
            text: new ol.style.Text({
              font: 'bold 11px "Open Sans", "Arial Unicode MS", "sans-serif"',
              fill: new ol.style.Fill({
                color: 'black'
              }),
              overflow: true,
              offsetX: leftTopPixel[0] - centerPixel[0],
              offsetY: centerPixel[1] - leftTopPixel[1],
              textAlign: 'left',
              text: feature.get('text')
            })
            
          }));
        } else {
          styles.push(new ol.style.Style({
            stroke: new ol.style.Stroke({
              color: '#ff0000',
              width: 2
            }),
            fill: new ol.style.Fill({
              color: 'rgba(255,0,0,0.3)',
            })
          }));
        }
        return styles;
      };
      
      // 図形を描画するレイヤーを定義する
      var vectorSource = new ol.source.Vector();
      var vectorLayer = new ol.layer.Vector({
        source: vectorSource,
        style: styleFunction
      });
      vectorLayer.set('name', 'vectorLayer');
      
      // 描画用ボタンの配置
      // マーカーボタン
      var MarkerControl = (function (Control) {
        function MarkerControl(opt_options) {
          var options = opt_options || {};

          var button = document.createElement('button');
          button.innerHTML = '※';
          button.name = 'Point';
          button.classList.add('map-button');

          var element = document.createElement('div');
          element.className = 'ol-unselectable ol-control';
          element.style.top = '100px';
          element.style.left = '5px';
          element.appendChild(button);

          Control.call(this, {
            element: element,
            target: options.target
          });

          button.addEventListener('click', this.drawMarker.bind(this), false);
        }

        if ( Control ) MarkerControl.__proto__ = Control;
        MarkerControl.prototype = Object.create( Control && Control.prototype );
        MarkerControl.prototype.constructor = MarkerControl;

        MarkerControl.prototype.drawMarker = function drawMarker () {
          addInteractions('Point');
        };

        return MarkerControl;
      }(ol.control.Control));
      
      // Linstringボタン
      var LineStringControl = (function (Control) {
        function LineStringControl(opt_options) {
          var options = opt_options || {};

          var button = document.createElement('button');
          button.innerHTML = '＜';
          button.name = 'LineString';
          button.classList.add('map-button');

          var element = document.createElement('div');
          element.className = 'ol-unselectable ol-control';
          element.style.top = '140px';
          element.style.left = '5px';
          element.appendChild(button);

          Control.call(this, {
            element: element,
            target: options.target
          });

          button.addEventListener('click', this.drawLineString.bind(this), false);
        }

        if ( Control ) LineStringControl.__proto__ = Control;
        LineStringControl.prototype = Object.create( Control && Control.prototype );
        LineStringControl.prototype.constructor = LineStringControl;

        LineStringControl.prototype.drawLineString = function drawLineString () {
          addInteractions('LineString');
        };

        return LineStringControl;
      }(ol.control.Control));
      
      // 円ボタン
      var CircleControl = (function (Control) {
        function CircleControl(opt_options) {
          var options = opt_options || {};

          var button = document.createElement('button');
          button.innerHTML = 'О';
          button.name = 'Circle';
          button.classList.add('map-button');

          var element = document.createElement('div');
          element.className = 'ol-unselectable ol-control';
          element.style.top = '180px';
          element.style.left = '5px';
          element.appendChild(button);

          Control.call(this, {
            element: element,
            target: options.target
          });

          button.addEventListener('click', this.drawCircle.bind(this), false);
        }

        if ( Control ) CircleControl.__proto__ = Control;
        CircleControl.prototype = Object.create( Control && Control.prototype );
        CircleControl.prototype.constructor = CircleControl;

        CircleControl.prototype.drawCircle = function drawCircle () {
          addInteractions('Circle');
        };

        return CircleControl;
      }(ol.control.Control));
      
      // 多角形ボタン
      var PolygonControl = (function (Control) {
        function PolygonControl(opt_options) {
          var options = opt_options || {};

          var button = document.createElement('button');
          button.innerHTML = '△';
          button.name = 'Polygon';
          button.classList.add('map-button');

          var element = document.createElement('div');
          element.className = 'ol-unselectable ol-control';
          element.style.top = '220px';
          element.style.left = '5px';
          element.appendChild(button);

          Control.call(this, {
            element: element,
            target: options.target
          });

          button.addEventListener('click', this.drawPolygon.bind(this), false);
        }

        if ( Control ) PolygonControl.__proto__ = Control;
        PolygonControl.prototype = Object.create( Control && Control.prototype );
        PolygonControl.prototype.constructor = PolygonControl;

        PolygonControl.prototype.drawPolygon = function drawPolygon () {
          addInteractions('Polygon');
        };

        return PolygonControl;
      }(ol.control.Control));
      
      // テキストボタン
      var TextControl = (function (Control) {
        function TextControl(opt_options) {
          var options = opt_options || {};

          var button = document.createElement('button');
          button.innerHTML = 'Ｔ';
          button.name = 'Text';
          button.classList.add('map-button');

          var element = document.createElement('div');
          element.className = 'ol-unselectable ol-control';
          element.style.top = '100px';
          element.style.left = '45px';
          element.appendChild(button);

          Control.call(this, {
            element: element,
            target: options.target
          });

          button.addEventListener('click', this.drawText.bind(this), false);
        }

        if ( Control ) TextControl.__proto__ = Control;
        TextControl.prototype = Object.create( Control && Control.prototype );
        TextControl.prototype.constructor = TextControl;

        TextControl.prototype.drawText = function drawText () {
          addInteractions('Text');
        };

        return TextControl;
      }(ol.control.Control));
      
      // 矩形ボタン
      var RectangleControl = (function (Control) {
        function RectangleControl(opt_options) {
          var options = opt_options || {};

          var button = document.createElement('button');
          button.innerHTML = 'ロ';
          button.name = 'Rectangle';
          button.classList.add('map-button');

          var element = document.createElement('div');
          element.className = 'ol-unselectable ol-control';
          element.style.top = '140px';
          element.style.left = '45px';
          element.appendChild(button);

          Control.call(this, {
            element: element,
            target: options.target
          });

          button.addEventListener('click', this.drawRectangle.bind(this), false);
        }

        if ( Control ) RectangleControl.__proto__ = Control;
        RectangleControl.prototype = Object.create( Control && Control.prototype );
        RectangleControl.prototype.constructor = RectangleControl;

        RectangleControl.prototype.drawRectangle = function drawRectangle () {
          addInteractions('Rectangle');
        };

        return RectangleControl;
      }(ol.control.Control));

      // 地図の初期化
      var map = new ol.Map({
        controls: ol.control.defaults().extend([
          // マーカーボタン
          new MarkerControl(),
          // LineStringボタン
          new LineStringControl(),
          // 円ボタン
          new CircleControl(),
          // 多角形ボタン
          new PolygonControl(),
          // テキストボタン
          new TextControl(),
          // 矩形ボタン
          new RectangleControl(),
        ]),
        target: 'map',
        layers: [
          new ol.layer.Tile({
            preload: 4,
            source: new ol.source.OSM()
          }), vectorLayer
        ],
        loadTilesWhileAnimating: true,
        view: new ol.View({
            center: ol.proj.fromLonLat([134.227352, 35.539909]),
            zoom: 13
        })
      });

      // 図形描画処理
      var draw, snap;
      function addInteractions(type) {
        // 描画モードの切り替え
        if (draw) {
          map.removeInteraction(draw);
          draw = null;
        }
        var shape = type;
        var geometryFunction;
        if (type == 'Text' || type == 'Rectangle') {
          type = 'Circle';
          geometryFunction = ol.interaction.Draw.createBox();
        }
        
        draw = new ol.interaction.Draw({
          source: vectorSource,
          type: type,
          geometryFunction: geometryFunction,
          geometryName: shape
        });
        
        draw.on('drawend', function(e){
          var shape = e.feature.getGeometryName();
          e.feature.set('shape', shape);

          if (shape == 'Text') {
            // テキストの場合
            inputText(e.feature);
          }
        });
        map.addInteraction(draw);
        
        // マウスカーソルが図形の座標に近づいたときにカーソルを合わせる
        if (!snap) {
          snap = new ol.interaction.Snap({source: vectorSource});
          map.addInteraction(snap);
        }
        
        // 現在の描画モードのボタンを色付けする
        $(".map-button").css('color', 'white');
        $(".map-button[name='" + shape + "']").css('color', 'red');
      }

      var popup = new ol.Overlay({
        element: document.getElementById('popup')
      });
      map.addOverlay(popup);

      function inputText(feature) {
        var element = popup.getElement();
        var coordinate = feature.getGeometry().getCoordinates()[0][3];
        $(element).popover('destroy');
        popup.setPosition(coordinate);
        $(element).popover({
          placement: 'top',
          html: true,
          content: '<div id="_popup"></div>'
        }).on('shown.bs.popover', function(e){
          var popover = $(this);
          $(this).parent().find('#_popup').html('<p><textarea id="txt"></textarea></p><p><input type="button" id="ok" value="ok"/>&nbsp<input type="button" id="cancel" value="cancel"/></p>');
          $(this).parent().find('#cancel').on('click', function(e){
            $(element).popover('destroy');
          });
          var txt = $(this).parent('div').find('#txt');
          $(this).parent().find('#ok').on('click', function(e){
            feature.set('text', txt.val());
            $(element).popover('destroy');
          });
        });
        $(element).popover('show').on('shown.bs.popover', function(e){
          var popover = $(this);
          $(this).parent().find('#cancel').on('click', function(e){
            $(element).popover('destroy');
          });
        });
      }
    </script>
  </body>
</html>

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<!DOCTYPE html>

<html>

<head>

</head>

<body>

// 描画された図形に適用されるスタイル

var styleFunction = function(feature) {

var geometry = feature.getGeometry();

var shape = feature.get('shape');

var styles = [];

if (geometry.getType() == 'Point') {

// 点の場合、マーカー配置

styles.push(new ol.style.Style({

image: new ol.style.Icon ({

anchor: [0.5, 46],

anchorXUnits: 'fraction',

anchorYUnits: 'pixels',

opacity: 0.95,

src: 'https://openlayers.org/en/latest/examples/data/icon.png'

})

}));

} else if (geometry.getType() == 'LineString'){

styles.push(new ol.style.Style({

stroke: new ol.style.Stroke({

color: '#ff0000',

width: 2

})

}));

} else if (shape == 'Text') {

var extent = ol.extent.boundingExtent(geometry.getCoordinates()[0]);

var center = [(extent[2] - extent[0]) / 2 + extent[0], (extent[3] - extent[1]) / 2 + extent[1]];

var centerPixel = map.getPixelFromCoordinate(center);

var leftTopPixel = map.getPixelFromCoordinate([extent[0], extent[1]]);

styles.push(new ol.style.Style({

stroke: new ol.style.Stroke({

color: 'rgba(0,0,0,0)',

width: 1

}),

text: new ol.style.Text({

font: 'bold 11px "Open Sans", "Arial Unicode MS", "sans-serif"',

fill: new ol.style.Fill({

color: 'black'

}),

overflow: true,

offsetX: leftTopPixel[0] - centerPixel[0],

offsetY: centerPixel[1] - leftTopPixel[1],

textAlign: 'left',

text: feature.get('text')

})

}));

} else {

styles.push(new ol.style.Style({

stroke: new ol.style.Stroke({

color: '#ff0000',

width: 2

}),

fill: new ol.style.Fill({

color: 'rgba(255,0,0,0.3)',

})

}));

}

return styles;

};

// 図形を描画するレイヤーを定義する

var vectorSource = new ol.source.Vector();

var vectorLayer = new ol.layer.Vector({

source: vectorSource,

style: styleFunction

});

vectorLayer.set('name', 'vectorLayer');

// 描画用ボタンの配置

// マーカーボタン

var MarkerControl = (function (Control) {

function MarkerControl(opt_options) {

var options = opt_options || {};

var button = document.createElement('button');

button.innerHTML = '※';

button.name = 'Point';

button.classList.add('map-button');

var element = document.createElement('div');

element.className = 'ol-unselectable ol-control';

element.style.top = '100px';

element.style.left = '5px';

element.appendChild(button);

Control.call(this, {

element: element,

target: options.target

});

button.addEventListener('click', this.drawMarker.bind(this), false);

}

if ( Control ) MarkerControl.__proto__ = Control;

MarkerControl.prototype = Object.create( Control && Control.prototype );

MarkerControl.prototype.constructor = MarkerControl;

MarkerControl.prototype.drawMarker = function drawMarker () {

addInteractions('Point');

};

return MarkerControl;

}(ol.control.Control));

// Linstringボタン

var LineStringControl = (function (Control) {

function LineStringControl(opt_options) {

var options = opt_options || {};

var button = document.createElement('button');

button.innerHTML = '＜';

button.name = 'LineString';

button.classList.add('map-button');

var element = document.createElement('div');

element.className = 'ol-unselectable ol-control';

element.style.top = '140px';

element.style.left = '5px';

element.appendChild(button);

Control.call(this, {

element: element,

target: options.target

});

button.addEventListener('click', this.drawLineString.bind(this), false);

}

if ( Control ) LineStringControl.__proto__ = Control;

LineStringControl.prototype = Object.create( Control && Control.prototype );

LineStringControl.prototype.constructor = LineStringControl;

LineStringControl.prototype.drawLineString = function drawLineString () {

addInteractions('LineString');

};

return LineStringControl;

}(ol.control.Control));

// 円ボタン

var CircleControl = (function (Control) {

function CircleControl(opt_options) {

var options = opt_options || {};

var button = document.createElement('button');

button.innerHTML = 'О';

button.name = 'Circle';

button.classList.add('map-button');

var element = document.createElement('div');

element.className = 'ol-unselectable ol-control';

element.style.top = '180px';

element.style.left = '5px';

element.appendChild(button);

Control.call(this, {

element: element,

target: options.target

});

button.addEventListener('click', this.drawCircle.bind(this), false);

}

if ( Control ) CircleControl.__proto__ = Control;

CircleControl.prototype = Object.create( Control && Control.prototype );

CircleControl.prototype.constructor = CircleControl;

CircleControl.prototype.drawCircle = function drawCircle () {

addInteractions('Circle');

};

return CircleControl;

}(ol.control.Control));

// 多角形ボタン

var PolygonControl = (function (Control) {

function PolygonControl(opt_options) {

var options = opt_options || {};

var button = document.createElement('button');

button.innerHTML = '△';

button.name = 'Polygon';

button.classList.add('map-button');

var element = document.createElement('div');

element.className = 'ol-unselectable ol-control';

element.style.top = '220px';

element.style.left = '5px';

element.appendChild(button);

Control.call(this, {

element: element,

target: options.target

});

button.addEventListener('click', this.drawPolygon.bind(this), false);

}

if ( Control ) PolygonControl.__proto__ = Control;

PolygonControl.prototype = Object.create( Control && Control.prototype );

PolygonControl.prototype.constructor = PolygonControl;

PolygonControl.prototype.drawPolygon = function drawPolygon () {

addInteractions('Polygon');

};

return PolygonControl;

}(ol.control.Control));

// テキストボタン

var TextControl = (function (Control) {

function TextControl(opt_options) {

var options = opt_options || {};

var button = document.createElement('button');

button.innerHTML = 'Ｔ';

button.name = 'Text';

button.classList.add('map-button');

var element = document.createElement('div');

element.className = 'ol-unselectable ol-control';

element.style.top = '100px';

element.style.left = '45px';

element.appendChild(button);

Control.call(this, {

element: element,

target: options.target

});

button.addEventListener('click', this.drawText.bind(this), false);

}

if ( Control ) TextControl.__proto__ = Control;

TextControl.prototype = Object.create( Control && Control.prototype );

TextControl.prototype.constructor = TextControl;

TextControl.prototype.drawText = function drawText () {

addInteractions('Text');

};

return TextControl;

}(ol.control.Control));

// 矩形ボタン

var RectangleControl = (function (Control) {

function RectangleControl(opt_options) {

var options = opt_options || {};

var button = document.createElement('button');

button.innerHTML = 'ロ';

button.name = 'Rectangle';

button.classList.add('map-button');

var element = document.createElement('div');

element.className = 'ol-unselectable ol-control';

element.style.top = '140px';

element.style.left = '45px';

element.appendChild(button);

Control.call(this, {

element: element,

target: options.target

});

button.addEventListener('click', this.drawRectangle.bind(this), false);

}

if ( Control ) RectangleControl.__proto__ = Control;

RectangleControl.prototype = Object.create( Control && Control.prototype );

RectangleControl.prototype.constructor = RectangleControl;

RectangleControl.prototype.drawRectangle = function drawRectangle () {

addInteractions('Rectangle');

};

return RectangleControl;

}(ol.control.Control));

// 地図の初期化

var map = new ol.Map({

controls: ol.control.defaults().extend([

// マーカーボタン

new MarkerControl(),

// LineStringボタン

new LineStringControl(),

// 円ボタン

new CircleControl(),

// 多角形ボタン

new PolygonControl(),

// テキストボタン

new TextControl(),

// 矩形ボタン

new RectangleControl(),

]),

target: 'map',

layers: [

new ol.layer.Tile({

preload: 4,

source: new ol.source.OSM()

}), vectorLayer

loadTilesWhileAnimating: true,

view: new ol.View({

center: ol.proj.fromLonLat([134.227352, 35.539909]),

zoom: 13

})

});

// 図形描画処理

var draw, snap;

function addInteractions(type) {

// 描画モードの切り替え

if (draw) {

map.removeInteraction(draw);

draw = null;

}

var shape = type;

var geometryFunction;

if (type == 'Text' || type == 'Rectangle') {

type = 'Circle';

geometryFunction = ol.interaction.Draw.createBox();

}

draw = new ol.interaction.Draw({

source: vectorSource,

type: type,

geometryFunction: geometryFunction,

geometryName: shape

});

draw.on('drawend', function(e){

var shape = e.feature.getGeometryName();

e.feature.set('shape', shape);

if (shape == 'Text') {

// テキストの場合

inputText(e.feature);

}

});

map.addInteraction(draw);

// マウスカーソルが図形の座標に近づいたときにカーソルを合わせる

if (!snap) {

snap = new ol.interaction.Snap({source: vectorSource});

map.addInteraction(snap);

}

// 現在の描画モードのボタンを色付けする

$(".map-button").css('color', 'white');

$(".map-button[name='" + shape + "']").css('color', 'red');

}

var popup = new ol.Overlay({

element: document.getElementById('popup')

});

map.addOverlay(popup);

function inputText(feature) {

var element = popup.getElement();

var coordinate = feature.getGeometry().getCoordinates()[0][3];

$(element).popover('destroy');

popup.setPosition(coordinate);

$(element).popover({

placement: 'top',

html: true,

content: '<div id="_popup"></div>'

}).on('shown.bs.popover', function(e){

var popover = $(this);

$(this).parent().find('#_popup').html('<p><textarea id="txt"></textarea></p><p><input type="button" id="ok" value="ok"/>&nbsp<input type="button" id="cancel" value="cancel"/></p>');