[OpenLayers-Users] ModifyFeature: Rotate Center Point and Control Point

[Eric Lemoine]

Hi. Thanks for sharing your code.

Adding a getCentroid function to the Geometry class would make sense
to me. Does your getCenter func effectively calculate the centroid?
Also, the centroid should be cached in a property of the geom to avoid
calculating it multiple times (the cache should obviously be cleared
when the coords are changed). That'be great if you could open a ticket
for that, with your patch.

And yes, I think it'd be good that the modify feature control could be
configured so that the rotate and drag handles are rendered at the
centroid of the feature. But I think this should be optional, for the
cases when it costs too much to calculate the centroid.
This patch would go in a ticket of its own.

Thanks,

Eric

2008/11/6, carls <carlshe at 163.com>:
>
> I just try to do some modification to ModifyFeature.js and Geometry.js.
>
>  one function 'GetCenter()' is added to OpenLayers.Geometry, and a little
> modification is applied to 'collectDragHandle' and 'collectRadiusHandle' of
> ModifyFeature.js.
>
> for Geometry.js:
>
>
> GetCenter: function() {
>         var vertices = new Array();
>         var center = new OpenLayers.Geometry.Point(0, 0);
>         var xx = 0, yy = 0;
>         /**
>         * Method: Collect All Vertices
>         */
>         function collectAllVertices(geometry, vertices) {
>             var i, vertex, component, len;
>             if (geometry.CLASS_NAME == "OpenLayers.Geometry.Point") {
>                 vertex = new OpenLayers.Feature.Vector(this);
>                 vertices.push(vertex);
>             } else {
>                 var numVert = geometry.components.length;
>                 if (geometry.CLASS_NAME == "OpenLayers.Geometry.LinearRing")
> {
>                     numVert -= 1;
>                 }
>                 for (i = 0; i < numVert; ++i) {
>                     component = geometry.components[i];
>                     if (component.CLASS_NAME == "OpenLayers.Geometry.Point")
> {
>                         vertex = new OpenLayers.Feature.Vector(component);
>                         vertices.push(vertex);
>                     } else {
>                         collectAllVertices(component, vertices);
>                     }
>                 }
>             }
>         }
>
>         collectAllVertices(this,vertices);
>         if (vertices.length > 0) {
>             for (ii in vertices) {
>                 xx += vertices[ii].geometry.x;
>                 yy += vertices[ii].geometry.y;
>             }
>             center = new OpenLayers.Geometry.Point(xx / vertices.length, yy
> / vertices.length);
>         }
>         return center;
>     },
>
>
> for ModifyFeature.js:
>
> /**
>     * Method: collectDragHandle
>     * Collect the drag handle for the selected geometry.
>     */
>     collectDragHandle: function() {
>         var geometry = this.feature.geometry;
>         ///var center = geometry.getBounds().getCenterLonLat();
>         //var originGeometry = new OpenLayers.Geometry.Point(
>         //    center.lon, center.lat
>         //);
>         var originGeometry = geometry.GetCenter();
>         var origin = new OpenLayers.Feature.Vector(originGeometry);
>         originGeometry.move = function(x, y) {
>             OpenLayers.Geometry.Point.prototype.move.call(this, x, y);
>             geometry.move(x, y);
>         };
>         this.dragHandle = origin;
>         this.layer.addFeatures([this.dragHandle], { silent: true });
>     },
>     /**
>     * Method: collectRadiusHandle
>     * Collect the radius handle for the selected geometry.
>     */
>     collectRadiusHandle: function() {
>         var geometry = this.feature.geometry;
>         var bounds = geometry.getBounds();
>         //var center = bounds.getCenterLonLat();
>         //var originGeometry = new OpenLayers.Geometry.Point(
>           //  center.lon, center.lat
>         //);
>         var originGeometry = geometry.GetCenter();
>         var radiusGeometry = new OpenLayers.Geometry.Point(
>             (bounds.right - originGeometry.x) * 1.3 + originGeometry.x,
> (bounds.bottom - originGeometry.y) * 1.3 + originGeometry.y
>         );
>
> var radius = new OpenLayers.Feature.Vector(radiusGeometry);
>         var resize = (this.mode & OpenLayers.Control.ModifyFeature.RESIZE);
>         var rotate = (this.mode & OpenLayers.Control.ModifyFeature.ROTATE);
>         radiusGeometry.move = function(x, y) {
>             OpenLayers.Geometry.Point.prototype.move.call(this, x, y);
>             var dx1 = this.x - originGeometry.x;
>             var dy1 = this.y - originGeometry.y;
>             var dx0 = dx1 - x;
>             var dy0 = dy1 - y;
>             if (rotate) {
>                 var a0 = Math.atan2(dy0, dx0);
>                 var a1 = Math.atan2(dy1, dx1);
>                 var angle = a1 - a0;
>                 angle *= 180 / Math.PI;
>                 geometry.rotate(angle, originGeometry);
>             }
>             if (resize) {
>                 var l0 = Math.sqrt((dx0 * dx0) + (dy0 * dy0));
>                 var l1 = Math.sqrt((dx1 * dx1) + (dy1 * dy1));
>                 geometry.resize(l1 / l0, originGeometry);
>             }
>         };
>         this.radiusHandle = radius;
>         this.layer.addFeatures([this.radiusHandle], { silent: true });
>     },
>
>
>
> I tested it and it seems can run well.
>
>
>
>
> carls wrote:
>>
>> while using ModifyFeature control on a regular polygon, it can be found
>> the rotate center is not right the real center of a regular polygon?  (try
>> it with a regular triangle)
>>
>> additionally, while rotating and modifying a rectangle parallel to the
>> axis, the control point for rotating might be at the same position of the
>> right-bottom corner of the rectangle, which confuses the action of
>> rotation and modifition, i.e. what i really need is to rotate the
>> rectangle, but really I moved the right-bottom corner of it.  This can be
>> resolved if the control point becomes a little more far to the center
>> point than any vertex of the geometry.
>>
>> It is not a big problem. But it will be better if imporved.
>>
>> Thanks!
>>
>
>
> -----
> Regards, Carl SHE
> --
> View this message in context:
> http://n2.nabble.com/ModifyFeature%3A-Rotate-Center-Point-and-Control-Point-tp1394002p1464935.html
> Sent from the OpenLayers Users mailing list archive at Nabble.com.
>
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