mysqldatabasegoogle-maps-api-3shapesoverlays

How to save a Google maps overlay shape in the database?


I want to save a Google maps overlay shape in the database. This is my code. It works perfectly but I just need to save all_shapes array in the database.

<html>
<head>

<style type="text/css">
  #map, html, body
  {
      padding: 0;
      margin: 0;
      height: 100%;
  }
</style>

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true&libraries=drawing,geometry"></script>

<script>
var coordinates = [];
var all_shapes = [];

var selectedShape;
</script>

<script>
function draw_shape()
{
    for(var i = 0; i < all_shapes.length; i++)
    {
        all_shapes[i].setMap(null);
    }

    for(var i = 0; i < all_shapes.length; i++)
    {
        all_shapes[i].setMap(map);
    }
}
</script>

<script>
function clearSelection()
{
    if(selectedShape)
    {
        selectedShape.setEditable(false);
        selectedShape = null;
    }
}

function setSelection(shape)
{
    clearSelection();
    selectedShape = shape;
    shape.setEditable(true);
}

function deleteSelectedShape()
{
    if (selectedShape)
    {
        selectedShape.setMap(null);
    }
}
</script>

<script>
function save_coordinates_to_array(newShapeArg)
{
    if(newShapeArg.type == google.maps.drawing.OverlayType.POLYGON)
    {
        var polygonBounds = newShapeArg.getPath();

        for(var i = 0 ; i < polygonBounds.length ; i++)
        {
            coordinates.push(polygonBounds.getAt(i).lat(), polygonBounds.getAt(i).lng());
        }
    }
    else
    {
        //alert("Not polygon");/////////////
    }   
}
</script>

<script>
var map;

function initialize()
{
    map = new google.maps.Map(document.getElementById('map'), {zoom: 12, center: new google.maps.LatLng(32.344, 51.048)});

    var drawingManager = new google.maps.drawing.DrawingManager();
    drawingManager.setMap(map);

    google.maps.event.addListener(drawingManager, 'overlaycomplete', function(e) {
        var newShape = e.overlay;
        newShape.type = e.type;

        all_shapes.push(newShape);

        setSelection(newShape);

        save_coordinates_to_array(newShape);

        google.maps.event.addListener(newShape, 'click', function() {setSelection(newShape)});
      });

    google.maps.event.addListener(map, 'click', function(e) {clearSelection();});
}

google.maps.event.addDomListener(window, 'load', initialize);
</script>
</head>

<body>
<table border="1">
  <tr>
    <td>Name</td>
    <td><input name="name" id="name" type="text"></td>
  </tr>
  <tr>
    <td>Color</td>
    <td>
      <table border="1" width="100%">
        <tr>
          <td bgcolor="#FF0000">&nbsp;</td>
          <td bgcolor="#00FF00">&nbsp;</td>
          <td bgcolor="#0000FF">&nbsp;</td>
        </tr>
      </table>
    </td>
  </tr>
  <tr>
    <td colspan="2"><input name="save" type="button" value="Save" onClick="draw_shape()"></td>
  </tr>
  <tr>
    <td colspan="2"><input name="delete" type="button" value="Delete" onClick="deleteSelectedShape()"></td>
  </tr>  
</table>

<div id="map"></div>
</body>

</html>

Where and how can I save the created overlay shapes in the database. All shapes are saved in the var all_shapes = []; array. What kind of type I have to choose for the field in database? I mean for example int, char, etc. I'm going to use MySQL and PHP.


Solution

  • When you simply want to store the shapes somehow, you may use a JSON-string, store it in e.g. a Text-column(char would be to small to store detailed polygons/polylines )

    Note: when you create the JSON-string, you must convert the properties(e.g. to native arrays or objects), you cannot store for example LatLng's directly, because the prototype will be lost when saving it. Pathes of polylines/polygons may be stored encoded

    Another approach: use multiple columns, e.g.

    1. a column(varchar) where you store the type(LatLng, Circle,Polyline,etc.)
    2. a column(geometry) where you store the geometric features(LatLng,Polygon or Polyline)
    3. a column(int) where you store a radius(used when you insert a circle)
    4. optionally column(text) where you store the style-options(when needed)

    The first suggestion would be sufficient when you simply want to store it.

    When you must be able to select particular shapes, e.g for a given area, use the 2nd suggestion. See http://dev.mysql.com/doc/refman/5.0/en/spatial-extensions.html for details of the spatial extensions


    2 functions that either remove the circular references and create storable objects, or restore the overlays from these stored objects.

    var IO={
      //returns array with storable google.maps.Overlay-definitions
      IN:function(arr,//array with google.maps.Overlays
                  encoded//boolean indicating if pathes should be stored encoded
                  ){
          var shapes     = [],
              goo=google.maps,
              shape,tmp;
    
          for(var i = 0; i < arr.length; i++)
          {   
            shape=arr[i];
            tmp={type:this.t_(shape.type),id:shape.id||null};
    
    
            switch(tmp.type){
               case 'CIRCLE':
                  tmp.radius=shape.getRadius();
                  tmp.geometry=this.p_(shape.getCenter());
                break;
               case 'MARKER': 
                  tmp.geometry=this.p_(shape.getPosition());   
                break;  
               case 'RECTANGLE': 
                  tmp.geometry=this.b_(shape.getBounds()); 
                 break;   
               case 'POLYLINE': 
                  tmp.geometry=this.l_(shape.getPath(),encoded);
                 break;   
               case 'POLYGON': 
                  tmp.geometry=this.m_(shape.getPaths(),encoded);
    
                 break;   
           }
           shapes.push(tmp);
        }
    
        return shapes;
      },
      //returns array with google.maps.Overlays
      OUT:function(arr,//array containg the stored shape-definitions
                   map//map where to draw the shapes
                   ){
          var shapes     = [],
              goo=google.maps,
              map=map||null,
              shape,tmp;
    
          for(var i = 0; i < arr.length; i++)
          {   
            shape=arr[i];       
    
            switch(shape.type){
               case 'CIRCLE':
                 tmp=new goo.Circle({radius:Number(shape.radius),
                                      center:this.pp_.apply(this,shape.geometry)});
                break;
               case 'MARKER': 
                 tmp=new goo.Marker({position:this.pp_.apply(this,shape.geometry)});
                break;  
               case 'RECTANGLE': 
                 tmp=new goo.Rectangle({bounds:this.bb_.apply(this,shape.geometry)});
                 break;   
               case 'POLYLINE': 
                 tmp=new goo.Polyline({path:this.ll_(shape.geometry)});
                 break;   
               case 'POLYGON': 
                 tmp=new goo.Polygon({paths:this.mm_(shape.geometry)});
    
                 break;   
           }
           tmp.setValues({map:map,id:shape.id})
           shapes.push(tmp);
        }
        return shapes;
      },
      l_:function(path,e){
        path=(path.getArray)?path.getArray():path;
        if(e){
          return google.maps.geometry.encoding.encodePath(path);
        }else{
          var r=[];
          for(var i=0;i<path.length;++i){
            r.push(this.p_(path[i]));
          }
          return r;
        }
      },
      ll_:function(path){
        if(typeof path==='string'){
          return google.maps.geometry.encoding.decodePath(path);
        }
        else{
          var r=[];
          for(var i=0;i<path.length;++i){
            r.push(this.pp_.apply(this,path[i]));
          }
          return r;
        }
      },
    
      m_:function(paths,e){
        var r=[];
        paths=(paths.getArray)?paths.getArray():paths;
        for(var i=0;i<paths.length;++i){
            r.push(this.l_(paths[i],e));
          }
         return r;
      },
      mm_:function(paths){
        var r=[];
        for(var i=0;i<paths.length;++i){
            r.push(this.ll_.call(this,paths[i]));
    
          }
         return r;
      },
      p_:function(latLng){
        return([latLng.lat(),latLng.lng()]);
      },
      pp_:function(lat,lng){
        return new google.maps.LatLng(lat,lng);
      },
      b_:function(bounds){
        return([this.p_(bounds.getSouthWest()),
                this.p_(bounds.getNorthEast())]);
      },
      bb_:function(sw,ne){
        return new google.maps.LatLngBounds(this.pp_.apply(this,sw),
                                            this.pp_.apply(this,ne));
      },
      t_:function(s){
        var t=['CIRCLE','MARKER','RECTANGLE','POLYLINE','POLYGON'];
        for(var i=0;i<t.length;++i){
           if(s===google.maps.drawing.OverlayType[t[i]]){
             return t[i];
           }
        }
      }
    
    }
    

    The array returned by IO.IN may be sended to a serverside script. The serverside script should iterate over this array and INSERT a JSON-string into the table:

    <?php
    $mysqli = new mysqli(/*args*/);
    $stmt = $mysqli->prepare('INSERT INTO `tableName`(`columnName`) VALUES (?)');
    $stmt->bind_param('s', $json);
    
    foreach($_POST['shapes'] as $value){
      $json = json_encode($value);
      $stmt->execute();
    }
    ?>
    

    to restore the shapes fetch them:

    <?php
    $json=array();
    $res=$mysqli->query('SELECT `columnName` from `tableName`');
    while ($row = $res->fetch_assoc()) {
            $json[]=json_decode($row['columnName']);
        }
    $res->close();
    $json=json_encode($json);
    ?>
    

    and pass the result to IO.OUT():

    IO.OUT(<?php echo $json;?>, someGoogleMapsInstance);
    

    Demo: http://jsfiddle.net/doktormolle/EdZk4/show/