func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op)
Draw calls DrawMask with a nil mask.
func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)
DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.
type Drawer interface {
// Draw aligns r.Min in dst with sp in src and then replaces the
// rectangle r in dst with the result of drawing src on dst.
Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
}
Drawer contains the Draw method.
var FloydSteinberg Drawer = floydSteinberg{}
FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error diffusion.
type Image interface {
image.Image
Set(x, y int, c color.Color)
}
Image is an image.Image with a Set method to change a single pixel.
type Op int
Op is a Porter-Duff compositing operator.
const (
// Over specifies ``(src in mask) over dst''.
Over Op = iota
// Src specifies ``src in mask''.
Src
)
func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
Draw implements the Drawer interface by calling the Draw function with this Op.
type Quantizer interface {
// Quantize appends up to cap(p) - len(p) colors to p and returns the
// updated palette suitable for converting m to a paletted image.
Quantize(p color.Palette, m image.Image) color.Palette
}
Quantizer produces a palette for an image.