Package draw

func Draw ¶

func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op)

Draw calls DrawMask with a nil mask.

func DrawMask ¶

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 ¶

Drawer contains the Draw method.

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)
}

FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error diffusion.

var FloydSteinberg Drawer = floydSteinberg{}

type Image ¶

Image is an image.Image with a Set method to change a single pixel.

type Image interface {
        image.Image
        Set(x, y int, c color.Color)
}

type Op ¶

Op is a Porter-Duff compositing operator.

type Op int

const (
        // Over specifies ``(src in mask) over dst''.
        Over Op = iota
        // Src specifies ``src in mask''.
        Src
)

func (Op) Draw ¶

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 ¶

Quantizer produces a palette for an image.

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
}