Sets the image source to apply to shape outlines. When null, shape outlines are displayed in the outline color.
When non-null, image pixels appear along shape outlines, with each image pixel multiplied by the outline RGBA
color. Use a white outline color to display the original image pixels.
Outline images appear as a one-dimensional repeating pattern that fills each shape's outline. The first row of
image pixels is repeated linearly along shape outlines in screen coordinates, with camera perspective applied to
the pattern.
Dashed shape outlines are accomplished with a one-dimensional outline image containing a mix of a transparent
pixels and white pixels. The image width indicates the pattern length in screen coordinates, while the
transparent pixels and white pixels indicate the dashing pattern. To display dashed lines similar to OpenGL's
classic line stippling feature, see
ImageSource#fromLineStipple(int,short).