diff options
Diffstat (limited to 'src/pkg/image/image.go')
| -rw-r--r-- | src/pkg/image/image.go | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/src/pkg/image/image.go b/src/pkg/image/image.go index bf75a51261..f4c38d28a6 100644 --- a/src/pkg/image/image.go +++ b/src/pkg/image/image.go @@ -563,14 +563,19 @@ func (p PalettedColorModel) Convert(c Color) Color { if len(p) == 0 { return nil } + return p[p.Index(c)] +} + +// Index returns the index of the palette color closest to c in Euclidean +// R,G,B space. +func (p PalettedColorModel) Index(c Color) int { cr, cg, cb, _ := c.RGBA() // Shift by 1 bit to avoid potential uint32 overflow in sum-squared-difference. cr >>= 1 cg >>= 1 cb >>= 1 - result := Color(nil) - bestSSD := uint32(1<<32 - 1) - for _, v := range p { + ret, bestSSD := 0, uint32(1<<32-1) + for i, v := range p { vr, vg, vb, _ := v.RGBA() vr >>= 1 vg >>= 1 @@ -578,11 +583,10 @@ func (p PalettedColorModel) Convert(c Color) Color { dr, dg, db := diff(cr, vr), diff(cg, vg), diff(cb, vb) ssd := (dr * dr) + (dg * dg) + (db * db) if ssd < bestSSD { - bestSSD = ssd - result = v + ret, bestSSD = i, ssd } } - return result + return ret } // A Paletted is an in-memory image backed by a 2-D slice of uint8 values and a PalettedColorModel. @@ -610,6 +614,13 @@ func (p *Paletted) At(x, y int) Color { return p.Palette[p.Pix[y*p.Stride+x]] } +func (p *Paletted) Set(x, y int, c Color) { + if !(Point{x, y}.In(p.Rect)) { + return + } + p.Pix[y*p.Stride+x] = uint8(p.Palette.Index(c)) +} + func (p *Paletted) ColorIndexAt(x, y int) uint8 { if !(Point{x, y}.In(p.Rect)) { return 0 |