Question

stackoverflow用户，我需要绘制圆圈，在Openlayer的GWT包装器中，我使用了DrawFeature，ModifyFeature控件，但是无法找到绘制Circle的控件，或者带有示例welcome的任何建议。例如：

import org.gwtopenmaps.openlayers.client.control.*;    
Vector vectorLayer = new Vector("Vector Layer");    
ModifyFeature mod = new ModifyFeature(vectorLayer);

像这是圈子的任何绘画功能？

Answer 1

您想为圆圈启用DrawFeature，还是想在图层上添加圆圈？

为圆圈启用DrawFeature：

//功能选项 DrawFeatureOptions drawFeatureOptions = new DrawFeatureOptions（）;

// Handler option for circle
RegularPolygonHandlerOptions handlerOptions = new RegularPolygonHandlerOptions();
// 30 side is ok for a circle
handlerOptions.setSides(30);
handlerOptions.setSnapAngle(0);
handlerOptions.setIrregular(false);

// Add the handler option to the DrawFeatureOptions
drawFeatureOptions.setHandlerOptions(handlerOptions);

// create the draw feature control
DrawFeature drawCircleFeatureControl = new DrawFeature(geometryFeaturesLayer, new RegularPolygonHandler(),
        drawFeatureOptions);

// Add the control to the map
map.addControl(drawCircleFeatureControl);

在图层上添加圆圈

在openlayers中有一个javascript方法：OpenLayers.Geometry.Polygon.createRegularPolygon 我无法在GWT openlayers中找到它，所以你必须调用javascript方法：

    /**
 * Create a regular polygon around a radius. Useful for creating circles and the like.
 * 
 * @param origin {OpenLayers.Geometry.Point} center of polygon.
 * @param radius {Float} distance to vertex, in map units.
 * @param sides {Integer} Number of sides. 20 approximates a circle.
 * @param rotation {Float} original angle of rotation, in degrees.
 * @return Polygon
 */
public static native JSObject jsCreateRegularPolygon(JSObject origin, Float radius, Integer sides, Float rotation)
/*-{
    return $wnd.OpenLayers.Geometry.Polygon.createRegularPolygon(origin, radius, sides, rotation);
}-*/;

然后从您的代码中调用它以创建您的圈子

JSObject polygonJSObject = jsCreateRegularPolygon(point, 100f, 30, 45f); // with 30 sides for a circle
Polygon circle = Polygon.narrowToPolygon(polygonJSObject);

GWT Openlayer绘制圆矢量特征

1 个答案: