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flomap-shadow
flomap-outline

4.11 Effects🔗ℹ

procedure

(flomap-shadow fm σ [color])  flomap

  fm : flomap
  σ : Real
  color : (Option (U (Vectorof Real) FlVector)) = #f
Returns the alpha (zeroth) component of fm, blurred with standard deviation σ and colorized by color. Assumes fm and color are alpha-multiplied; see Opacity (Alpha Components).

If color = #f, it is interpreted as (flvector 1.0 0.0 ...), or opaque black.

Examples:
> (flomap->bitmap
   (flomap-shadow (flomap-inset text-fm 12) 4 #(1/2 1/8 0 1/4)))

image

> (flomap->bitmap
   (flomap-cc-superimpose
    (flomap-shadow (flomap-inset text-fm 12) 4 #(1/2 1/8 0 1/4))
    text-fm))

image

procedure

(flomap-outline fm radius [color])  flomap

  fm : flomap
  radius : Real
  color : (Option (U (Vectorof Real) FlVector)) = #f
Returns a flomap that outlines fm with a radius-thick line when fm is superimposed over it. Assumes fm and color are alpha-multiplied; see Opacity (Alpha Components).

If color = #f, it is interpreted as (flvector 1.0 0.0 ...), or opaque black.

Examples:
> (flomap->bitmap
   (flomap-outline (flomap-inset text-fm 2) 2 #(1 0 1 1)))

image

> (flomap->bitmap
   (flomap-cc-superimpose
    (flomap-outline (flomap-inset text-fm 2) 2 #(1 0 1 1))
    text-fm))

image

The greatest alpha value in the returned outline is the greatest alpha value in fm. Because of this, flomap-outline does fine with flomaps with fully opaque regions that are made semi-transparent:
> (define trans-text-fm (fm* 0.5 text-fm))
> (flomap->bitmap trans-text-fm)

image

> (flomap->bitmap
   (flomap-cc-superimpose
    (flomap-outline (flomap-inset trans-text-fm 2) 2 #(1 0 1 1))
    trans-text-fm))

image

However, it does not do so well with flomaps that are partly opaque and partly semi-transparent:
> (define mixed-text-fm
    (flomap-vc-append text-fm (make-flomap 4 0 10) trans-text-fm))
> (flomap->bitmap
   (flomap-cc-superimpose
    (flomap-outline (flomap-inset mixed-text-fm 2) 2 #(1 0 1 1))
    mixed-text-fm))

image