我有一些仅使用单色笔画样式绘制的LineString要素。其中一些要素表示两个物体,因此除了初始笔画颜色外,我希望在其旁边有一条不同颜色的平行线。如果 ol/style/Stroke
有像 ol/style/Image
那样的偏移属性,这将是易如反掌的,但可悲的是它没有。如果我为这些要素创建偏移几何体,则在缩小的级别下它们将不可见。我的选择是什么?
我有一些仅使用单色笔画样式绘制的LineString要素。其中一些要素表示两个物体,因此除了初始笔画颜色外,我希望在其旁边有一条不同颜色的平行线。如果 ol/style/Stroke
有像 ol/style/Image
那样的偏移属性,这将是易如反掌的,但可悲的是它没有。如果我为这些要素创建偏移几何体,则在缩小的级别下它们将不可见。我的选择是什么?
var style = function(feature, resolution) {
var colors = ['green', 'yellow', 'red'];
var width = 4;
var styles = [];
for (var line = 0; line < colors.length; line++) {
var dist = width * resolution * (line - (colors.length-1)/2);
var geom = feature.getGeometry();
var coords = [];
var counter = 0;
geom.forEachSegment(function(from, to) {
var angle = Math.atan2(to[1] - from[1], to[0] - from[0]);
var newFrom = [
Math.sin(angle) * dist + from[0],
-Math.cos(angle) * dist + from[1]
];
var newTo = [
Math.sin(angle) * dist + to[0],
-Math.cos(angle) * dist + to[1]
];
coords.push(newFrom);
coords.push(newTo);
if (coords.length > 2) {
var intersection = math.intersect(coords[counter], coords[counter+1], coords[counter+2], coords[counter+3]);
coords[counter+1] = (intersection) ? intersection : coords[counter+1];
coords[counter+2] = (intersection) ? intersection : coords[counter+2];
counter += 2;
}
});
styles.push(
new ol.style.Style({
geometry: new ol.geom.LineString(coords),
stroke: new ol.style.Stroke({
color: colors[line],
width: width
})
})
);
}
return styles;
};
var raster = new ol.layer.Tile({
source: new ol.source.OSM()
});
var source = new ol.source.Vector();
var vector = new ol.layer.Vector({
source: source,
style: style
});
var map = new ol.Map({
layers: [raster, vector],
target: 'map',
view: new ol.View({
center: [-11000000, 4600000],
zoom: 4
})
});
map.addInteraction(new ol.interaction.Draw({
source: source,
type: 'LineString'
}));
html, body, .map {
margin: 0;
padding: 0;
width: 100%;
height: 100%;
}
<link href="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/css/ol.css" rel="stylesheet" />
<script src="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/build/ol.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/5.4.1/math.min.js"></script>
<div id="map" class="map"></div>
var white = [255, 255, 255, 1];
var blue = [0, 153, 255, 1];
var width = 3;
var pointStyle = new ol.style.Style({
image: new ol.style.Circle({
radius: width * 2,
fill: new ol.style.Fill({
color: blue
}),
stroke: new ol.style.Stroke({
color: white,
width: width / 2
})
}),
zIndex: Infinity
});
var style = function(feature, resolution) {
var widths = [10, 10];
var strokes = [
[
{
width: 4,
color: '#7af500'
}, {
width: 4,
color: '#55aa00',
lineDash: [7,9]
}
], [
{
width: 2,
color: 'black'
}, {
width: 8,
color: 'black',
lineDash: [2,14],
lineCap: 'butt'
}
]
];
var styles = [pointStyle];
var totalWidth = 0
for (var line = 0; line < widths.length; line++) {
totalWidth += widths[line];
}
var width = 0;
for (var line = 0; line < widths.length; line++) {
var dist = (width + widths[line]/2 - totalWidth/2) * resolution;
width += widths[line];
var geom = feature.getGeometry();
if (geom.forEachSegment) {
var coords = [];
var counter = 0;
geom.forEachSegment(function(from, to) {
var angle = Math.atan2(to[1] - from[1], to[0] - from[0]);
var newFrom = [
Math.sin(angle) * dist + from[0],
-Math.cos(angle) * dist + from[1]
];
var newTo = [
Math.sin(angle) * dist + to[0],
-Math.cos(angle) * dist + to[1]
];
coords.push(newFrom);
coords.push(newTo);
if (coords.length > 2) {
var intersection = math.intersect(coords[counter], coords[counter+1], coords[counter+2], coords[counter+3]);
coords[counter+1] = (intersection) ? intersection : coords[counter+1];
coords[counter+2] = (intersection) ? intersection : coords[counter+2];
counter += 2;
}
});
strokes[line].forEach( function(stroke) {
styles.push(
new ol.style.Style({
geometry: new ol.geom.LineString(coords),
stroke: new ol.style.Stroke(stroke)
})
);
});
}
}
return styles;
};
var raster = new ol.layer.Tile({
source: new ol.source.OSM()
});
var source = new ol.source.Vector();
var vector = new ol.layer.Vector({
source: source,
style: style
});
var map = new ol.Map({
layers: [raster, vector],
target: 'map',
view: new ol.View({
center: [-11000000, 4600000],
zoom: 4
})
});
map.addInteraction(new ol.interaction.Draw({
source: source,
style: style,
type: 'LineString'
}));
html, body, .map {
margin: 0;
padding: 0;
width: 100%;
height: 100%;
}
<link href="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/css/ol.css" rel="stylesheet" />
<script src="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/build/ol.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/5.4.1/math.min.js"></script>
<div id="map" class="map"></div>
我有一个可以工作的版本 - 但是当我缩放图表时就不行了。
我在图表上绘制线条(来自数据库),并使用我们的函数来绘制这些线条。
我尝试在此处插入代码,但我的JavaScript函数没有运行。如何在代码片段中使用函数?
function print_my_string( my_string )
{
console.log( my_string );
}
html, body, .map {
margin: 0;
padding: 0;
width: 100%;
height: 100%;
}
<link href="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/css/ol.css" rel="stylesheet" />
<script src="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/build/ol.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/5.4.1/math.min.js"></script>
<div id="map" class="map"></div>
// How do I use the java-script (Include before called...
<script>print_my_string( "Hello" );</script>
print_my_string( "Hello" );
函数调用放在 HTML 的 <script>
块中,而不是编辑器的代码部分? - Thomas
if
代码块也可以正常工作,非常好。你能解释一下整段代码的方法学吗?再次感谢。 - Aceif
块的编辑,但您能否详细说明主要部分的数学计算过程? - Ace