长期潜伏在这里的第一次海报,所以要温柔......
我正在构建一个地图,该地图使用通过PHP从MYSQL数据库解析的数据来设置geoJson文件定义的多边形的颜色(它使用Google开发站点上的this示例作为模板)。我遇到的问题是,当页面加载时,数据层不会自动初始化。
下面发布了完整的javascript / HTML,但我在初始化数据层时所使用的示例中使用的代码部分是:
google.maps.event.addListenerOnce(map.data, 'addfeature', function() {
google.maps.event.trigger(document.getElementById('price_select'),
'change');
});
这给了我错误“Uncaught TypeError:无法读取未定义的属性'setProperty'”。如果我注释掉监听器,数据层将加载正常,但只有在我从下拉列表中手动选择了一个新输入后(id ='price_select')。
我正在加载的geoJson文件相对较大(~14mb)所以我认为发生的事情是在整个文件加载之前侦听器正在触发('addfeature'等待第一个要添加的功能,但是我有> 2000)因此PHP解析的区域还没有相应的功能ID,它由loadGeoJson调用中的idPropertyName: 'Name'
参数设置。我不知道只有在整个GeoJson文件加载后才设置侦听器的方法。或者,我可能完全错误地认为这是错误的原因。
无论如何,下面的完整代码 - 我知道它有一些怪癖(例如我传递loadData函数一个参数,但不要使用它),但这些主要是因为我计划稍后添加更多功能。谢谢你的支持!
<script src="https://maps.googleapis.com/maps/api/js?v=3.exp"></script>
<script>
var map;
var priceMin = 1000000;
var priceMax = 0;
google.maps.event.addDomListener(window, 'load', function(){
map = new google.maps.Map(document.getElementById('map-canvas'), {
center: new google.maps.LatLng(53.587425,-1.663539),
zoom: 7,
});
// add styles
map.data.setStyle(styleFeature);
map.data.addListener('mouseover', mouseInToRegion);
map.data.addListener('mouseout', mouseOutOfRegion);
// initiate drop down functionality
var selectBox = document.getElementById('price_select');
google.maps.event.addDomListener(selectBox, 'change', function() {
clearData();
loadData(selectBox.options[selectBox.selectedIndex].value);
});
// load polygons
loadMapShapes();
});
function loadMapShapes(){
map.data.loadGeoJson('http://localhost/OS_raw.json',
{ idPropertyName: 'Name' });
//This is the listener that is supposed to initiate the data layer
google.maps.event.addListenerOnce(map.data, 'addfeature', function() {
google.maps.event.trigger(document.getElementById('price_select'),
'change');
});
// End listener
}
function loadData(variable){
var phpdistricts = (<?php echo $phpdistricts; ?>);
var phpprices = (<?php echo $phpprices; ?>);
for(var i=0; i<phpdistricts.length; i++){
var district = phpdistricts[i];
var price = parseInt(phpprices[i]);
// keep track of min and max values
if (price < priceMin) {
priceMin = price;
}
if (price > priceMax) {
priceMax = price;
}
console.log(map.data.getFeatureById(district));
//This is where the error triggers - feature is undefined according to console log above
map.data
.getFeatureById(district)
.setProperty('price', price);}
//end of problematic section
// update and display the legend
document.getElementById('census-min').textContent =
priceMin.toLocaleString();
document.getElementById('census-max').textContent =
priceMax.toLocaleString();
}
function clearData() {
priceMin = 1000000;
priceMax = 0;
map.data.forEach(function(row) {
row.setProperty('price', undefined);
});
document.getElementById('data-box').style.display = 'none';
document.getElementById('data-caret').style.display = 'none';
}
function styleFeature(feature) {
var low = [151, 83, 34]; // color of smallest datum
var high = [5, 69, 54]; // color of largest datum
// delta represents where the value sits between the min and max
var delta = (feature.getProperty('price') - priceMin) /
(priceMax - priceMin);
var color = [];
for (var i = 0; i < 3; i++) {
// calculate an integer color based on the delta
color[i] = (high[i] - low[i]) * delta + low[i];
}
// filters out areas without data
var showRow = true;
if (feature.getProperty('price') == null ||
isNaN(feature.getProperty('price'))) {
showRow = false;
}
var outlineWeight = 0.5, zIndex = 1;
if (feature.getProperty('state') === 'hover') {
outlineWeight = zIndex = 2;
}
return {
strokeWeight: outlineWeight,
strokeColor: '#fff',
zIndex: zIndex,
fillColor: 'hsl(' + color[0] + ',' + color[1] + '%,' + color[2] + '%)',
fillOpacity: 0.75,
visible: showRow
};
}
function mouseInToRegion(e) {
// set the hover state so the setStyle function can change the border
e.feature.setProperty('state', 'hover');
var percent = (e.feature.getProperty('price') - priceMin) /
(priceMax - priceMin) * 100;
// update the label
document.getElementById('data-label').textContent =
e.feature.getProperty('Name');
document.getElementById('data-value').textContent =
e.feature.getProperty('price');
document.getElementById('data-box').style.display = 'block';
document.getElementById('data-caret').style.display = 'block';
document.getElementById('data-caret').style.paddingLeft = percent + '%';
}
function mouseOutOfRegion(e) {
// reset the hover state, returning the border to normal
e.feature.setProperty('state', 'normal');
}
</script>
</head>
<body>
<div id="controls" class="nicebox">
<div>
<select id="price_select">
<option value="price">Jun '14</option>
<option value="price">Jun '14</option>
</select>
</div>
<div id="legend">
<div id="census-min">min</div>
<div class="color-key">
<span id="data-caret">◆</span>
</div>
<div id="census-max">max</div>
</div>
</div>
<div id="data-box" class="nicebox">
<label id="data-label" for="data-value">Area: </label>
<span id="data-value"></span>
</div>
<div id="map-canvas"></div>
</body>
</html>
答案 0 :(得分:0)
我没有完全明白你在这里问的问题,但你是否尝试过使用数据层事件而不是地图?
map.data.setStyle(
function(feature){
// Build your styles here based on feature properties.
return style_i_want_for_this_feature;
}
);
您的GeoJSON数据中的每个功能都会被调用,您可以适当地对待它。我以这种方式加载和设置具有数千个功能的功能集合。