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package ui
import (
"github.com/golang/freetype/raster"
"image"
"image/color"
"image/draw"
)
// BGRA is like RGBA but in wayland's byte order
type BGRA struct {
Pix []uint8
Stride int
Rect image.Rectangle
}
// NewBGRA returns a new BGRA image with the given bounds.
func NewBGRA(r image.Rectangle) *BGRA {
w, h := r.Dx(), r.Dy()
buf := make([]uint8, 4*w*h)
return &BGRA{buf, 4 * w, r}
}
func NewBGRAWithData(r image.Rectangle, data []uint8) *BGRA {
w, h := r.Dx(), r.Dy()
if len(data) < 4*w*h {
panic("not enough data supplied")
}
return &BGRA{data, 4 * w, r}
}
func (p *BGRA) ColorModel() color.Model { return color.RGBAModel }
func (p *BGRA) Bounds() image.Rectangle { return p.Rect }
func (p *BGRA) At(x, y int) color.Color {
return p.RGBAAt(x, y)
}
func (p *BGRA) RGBAAt(x, y int) color.RGBA {
if !(image.Point{x, y}.In(p.Rect)) {
return color.RGBA{}
}
i := p.PixOffset(x, y)
return color.RGBA{p.Pix[i+2], p.Pix[i+1], p.Pix[i+0], p.Pix[i+3]}
}
// PixOffset returns the index of the first element of Pix that corresponds to
// the pixel at (x, y).
func (p *BGRA) PixOffset(x, y int) int {
return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*4
}
func (p *BGRA) Set(x, y int, c color.Color) {
if !(image.Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
c1 := color.RGBAModel.Convert(c).(color.RGBA)
p.Pix[i+0] = c1.B
p.Pix[i+1] = c1.G
p.Pix[i+2] = c1.R
p.Pix[i+3] = c1.A
}
func (p *BGRA) SetRGBA(x, y int, c color.RGBA) {
if !(image.Point{x, y}.In(p.Rect)) {
return
}
i := p.PixOffset(x, y)
p.Pix[i+0] = c.B
p.Pix[i+1] = c.G
p.Pix[i+2] = c.R
p.Pix[i+3] = c.A
}
// SubImage returns an image representing the portion of the image p visible
// through r. The returned value shares pixels with the original image.
func (p *BGRA) SubImage(r image.Rectangle) image.Image {
r = r.Intersect(p.Rect)
// If r1 and r2 are Rectangles, r1.Intersect(r2) is not
// guaranteed to be inside either r1 or r2 if the intersection
// is empty. Without explicitly checking for this, the Pix[i:]
// expression below can panic.
if r.Empty() {
return &BGRA{}
}
i := p.PixOffset(r.Min.X, r.Min.Y)
return &BGRA{
Pix: p.Pix[i:],
Stride: p.Stride,
Rect: r,
}
}
// Opaque scans the entire image and reports whether it is fully opaque.
func (p *BGRA) Opaque() bool {
if p.Rect.Empty() {
return true
}
i0 := 0
i1 := p.Rect.Dx() * 4
for y := p.Rect.Min.Y; y < p.Rect.Max.Y; y++ {
for i := i0; i < i1; i += 4 {
if p.Pix[i+3] != 0xff {
return false
}
}
i0 += p.Stride
i1 += p.Stride
}
return true
}
// a BGRAPainter is used to interface with the freetype renderer and
// raster library
type BGRAPainter struct {
image *BGRA
r, g, b, a uint32
op draw.Op
}
func (p *BGRA) Painter() *BGRAPainter {
return &BGRAPainter{
image: p,
}
}
func (p *BGRAPainter) SetColor(c color.Color) {
p.r, p.g, p.b, p.a = c.RGBA()
}
func (p *BGRAPainter) Paint(spans []raster.Span, done bool) {
b := p.image.Rect
pix := p.image.Pix
for _, s := range spans {
if s.Y < b.Min.Y {
continue
}
if s.Y >= b.Max.Y {
// since spans are ordered, we know we're done
// at this point
return
}
if s.X0 < b.Min.X {
s.X0 = b.Min.X
}
if s.X1 > b.Max.X {
s.X1 = b.Max.X
}
if s.X0 >= s.X1 {
continue
}
// This code mimics drawGlyphOver in $GOROOT/src/image/draw/draw.go.
ma := s.Alpha
const m = 1<<16 - 1
i0 := (s.Y-b.Min.Y)*p.image.Stride + (s.X0-b.Min.X)*4
i1 := i0 + (s.X1-s.X0)*4
if p.op == draw.Over {
for i := i0; i < i1; i += 4 {
dr := uint32(pix[i+0])
dg := uint32(pix[i+1])
db := uint32(pix[i+2])
da := uint32(pix[i+3])
a := (m - (p.a * ma / m)) * 0x101
pix[i+0] = uint8((dr*a + p.r*ma) / m >> 8)
pix[i+1] = uint8((dg*a + p.g*ma) / m >> 8)
pix[i+2] = uint8((db*a + p.b*ma) / m >> 8)
pix[i+3] = uint8((da*a + p.a*ma) / m >> 8)
}
} else {
for i := i0; i < i1; i += 4 {
pix[i+0] = uint8(p.r * ma / m >> 8)
pix[i+1] = uint8(p.g * ma / m >> 8)
pix[i+2] = uint8(p.b * ma / m >> 8)
pix[i+3] = uint8(p.a * ma / m >> 8)
}
}
}
}
|
