How can I draw a shape with an inner hole ?
sotex opened this issue · 4 comments
I need to draw some shapes with inner holes. I don't know if there is a more convenient way.
Because I want to draw multiple such shapes on top of each other.
The method I currently use is:
1、Create a new canvas(Transparent background), Draw upper shell polygon.
2、Draw inner holes in transparent colors
3、Draw the contents of the new canvas onto the old canvas
Thanks.
Hi @sotex,
I think you 'll find what you want in this sample:
https://github.com/llgcode/draw2d/wiki/Samples#test-fill-style
regards
Laurent
Hi @llgcode,
thank for your help.
I have implemented this basic function and your work is really great!
I have a little question, and I hope to get your guidance.
This is the graphic I draw on the geojson.io website
Data are as follows:
{"type":"FeatureCollection","features":[{"type":"Feature","properties":{"stroke":"#0f2f9b","stroke-width":2,"stroke-opacity":1,"fill":"#a90501","fill-opacity":0.5},"geometry":{"type":"Polygon","coordinates":[[[100.2392578125,34.34343606848294],[97.998046875,30.41078179084589],[101.22802734375,27.702983735525862],[108.08349609375,28.844673680771795],[110.36865234374999,34.66935854524543],[112.8515625,35.209721645221386],[112.47802734375,31.89621446335144],[117.0703125,30.240086360983426],[117.57568359374999,34.939985151560435],[112.236328125,38.35888785866677],[100.2392578125,34.34343606848294]],[[101.05224609374999,32.02670629333614],[102.72216796875,33.394759218577995],[104.94140625,32.11980111179328],[103.38134765625,31.70947636001935],[103.1396484375,30.259067203213018],[101.05224609374999,32.02670629333614]],[[106.962890625,35.263561862152095],[110.7861328125,36.756490329505176],[111.09374999999999,36.27970720524017],[107.46826171874999,34.74161249883172],[106.962890625,35.263561862152095]]]}},{"type":"Feature","properties":{"stroke":"#ffffff","stroke-width":2,"stroke-opacity":1,"fill":"#ffff00","fill-opacity":0.5},"geometry":{"type":"Polygon","coordinates":[[[113.97216796875,35.99578538642032],[113.9501953125,35.22767235493586],[115.81787109375,34.63320791137959],[115.55419921875,31.522361470421437],[116.23535156249999,31.409912194070973],[116.4111328125,34.88593094075317],[113.97216796875,35.99578538642032]]]}}]}This is the result I draw following the wiki.
I think it is better to handle the overlay of the newly filled part with the original color, rather than simply covering it.
But I want to know if I can control simple coverage? Tanks.
HI @sotex ,
great and thank you :-), this library is working thanks to Nigel Tao from Google that wrote the freetype lib behind the wrapper I wrote. You have to be aware of the new API he wrote: https://github.com/golang/image. There's also other alternatives that work well too.
To answer your question, not sure what do you mean by controlling simple coverage. you can control the transparency with alpha part of the color.
regards