Any takers? Or am I on the wrong track here? Thanks in advance, Dan
Dan Garland wrote: > Hi all, > > I'm a Ruby on Rails developer working on my first project with > OpenLayers. I'm tasked with developing an free-hand eraser tool that can > erase features created by the drawFeatures tool. Amongst other things > we've tried, my thinking is moving towards creating a SVG mask, based on > the existing drawing tool, in which the 'erased' line is actually a > black line within a white, rectangular SVG mask, which when applied over > the top of the tile layer would mask any drawn features from underneath. > I anticipate something like this: > > <svg width="8cm" height="8cm" viewBox="0 0 800 800" version="1.1" > xmlns="http://www.w3.org/2000/svg"; > xmlns:xlink="http://www.w3.org/1999/xlink";> > <defs> > <mask id="Mask" maskUnits="userSpaceOnUse" x="0" y="0" width="3968" > height="2964"> > <rect x="0" y="0" width="3968" height="2964" fill="white" /> > <!-- The 'eraser' line --> > <polyline fill="none" stroke="black" stroke-width="25" > points="400,0 400,800" /> > </mask> > </defs> > > <!-- Example drawn features --> > > <polyline id="myline" points="0,0 800,800" fill="none" > stroke-opacity="1" stroke-width="25" stroke-linecap="round" > stroke-linejoin="round" stroke-dasharray="none"/> > <polyline id="myline2" points="0,100 800,100" fill="none" > stroke-opacity="1" stroke-width="25" stroke-linecap="round" > stroke-linejoin="round" stroke-dasharray="none"/> > <polyline id="myline3" points="0,400 800,400" fill="none" > stroke-opacity="1" stroke-width="25" stroke-linecap="round" > stroke-linejoin="round" stroke-dasharray="none"/> > > <use xlink:href="#myline" stroke="red" mask="url(#Mask)" /> > <use xlink:href="#myline2" stroke="red" mask="url(#Mask)" /> > <use xlink:href="#myline3" stroke="red" mask="url(#Mask)" /> > > </svg> > > The problems I face with this approach is knowing how best to manipulate > the existing SVG object being referenced by OpenLayers. I wonder whether > it is feasible in OpenLayers to develop a control based on the > drawFeature tool that > > 1) Adds the mask <defs> section to the SVG Root at startup > 2) Creates polyline elements with the mask > 3) Adds <use> elements for each element in the tile layer to connect the > id and the mask > > Before I dive in and spent hours in an unfamiliar area I wonder if any > OpenLayers developers have encountered this use case and have a better > solution, or can shed any light on this proposed approach. > > Best Regards, > Dan Garland > > _______________________________________________ > Users mailing list > [email protected] > http://openlayers.org/mailman/listinfo/users _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
