Add an outline to images via GDI+ with .NET Framework

Building a Stroke Class to outline your images via GDI+

I won’t prattle on. The aim was to find a way to transform this image:

Into this image (done in GIMP):

All this within the restraints of a winforms app for .NET framework 3.5 (don’t ask..).

I found this excellent answer on StackOverflow. I amalgamated this with a few other techniques (the main one being a fast blurring class to provide the option of blurred edges to the stroke – to essentially produce Glow) and got things working. The answer does depend on a SuperFastBlur alghorithm (see here) which was written in C#. I couldn’t be bothered to convert it to, so I just compiled it into a library and included it in my project.

Then, you simply include the Classes at the bottom of this page (I just saved the all to a single file). To apply a Stroke to your image, you then just use:

_image is either Image or Bitmap and the other parameters should be self explanatory. Here are some results:


And some unexpected funky effects by changing LineJoin:



Not perfect, but not bad for GDI+?

The code:


About stigzler 47 Articles
Chief crook and wattle bosher.

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