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rgb.go
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rgb.go
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// Copyright 2022 The Embedded Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fbdrv
import (
"image"
"image/color"
"image/draw"
)
type RGB struct {
fb FrameBuffer
pix []byte
width int
height int
stride int
r, g, b, a uint16
mvxy uint8
}
func NewRGB(fb FrameBuffer) *RGB {
return &RGB{fb: fb}
}
func (d *RGB) SetDir(dir int) image.Rectangle {
d.pix, d.width, d.height, d.stride, _, d.mvxy = d.fb.SetDir(dir)
var r image.Rectangle
if d.mvxy&MV == 0 {
r.Max.X = d.width
r.Max.Y = d.height
} else {
r.Max.X = d.height
r.Max.Y = d.width
}
return r
}
func (d *RGB) Flush() { d.pix = d.fb.Flush() }
func (d *RGB) Err(clear bool) error { return d.fb.Err(clear) }
func at128(img image.Image, x, y int) (r, g, b, a uint32) {
if img64, ok := img.(image.RGBA64Image); ok {
c := img64.RGBA64At(x, y)
return uint32(c.R), uint32(c.G), uint32(c.B), uint32(c.A)
}
return img.At(x, y).RGBA()
}
func (d *RGB) Draw(r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op draw.Op) {
var sr, sg, sb, sa uint32
srcIsUniform := false
if u, ok := src.(*image.Uniform); ok {
sr, sg, sb, sa = u.At(0, 0).RGBA() // TODO: use RGBA64At
srcIsUniform = true
}
minx, miny := r.Min.X, r.Min.Y
ox, oy := 3, d.stride
if d.mvxy&MV != 0 {
minx, miny = miny, minx
}
if d.mvxy&MX != 0 {
minx = d.width - 1 - minx
ox = -ox
}
if d.mvxy&MY != 0 {
miny = d.height - 1 - miny
oy = -oy
}
if d.mvxy&MV != 0 {
ox, oy = oy, ox
}
offset := miny*d.stride + minx*3
width, height := r.Dx(), r.Dy()
for y := 0; y < height; y++ {
o := offset
for x := 0; x < width; x++ {
if !srcIsUniform {
sr, sg, sb, sa = at128(src, sp.X+x, sp.Y+y)
}
ma := uint32(0xffff)
if mask != nil {
_, _, _, ma = at128(mask, mp.X+x, mp.Y+y)
}
pix := d.pix[o : o+3 : o+3] // see https://golang.org/issue/27857
dr, dg, db := sr, sg, sb
if sa&ma != 0xffff {
if op == draw.Over {
dr = uint32(pix[0])
dg = uint32(pix[1])
db = uint32(pix[2])
a := 0xffff - (sa * ma / 0xffff)
dr = ((dr|dr<<8)*a + sr*ma) / 0xffff
dg = ((dg|dg<<8)*a + sg*ma) / 0xffff
db = ((db|db<<8)*a + sb*ma) / 0xffff
} else if ma != 0xffff {
dr = sr * ma / 0xffff
dg = sg * ma / 0xffff
db = sb * ma / 0xffff
} else {
}
}
pix[0] = uint8(dr >> 8)
pix[1] = uint8(dg >> 8)
pix[2] = uint8(db >> 8)
o += ox
}
offset += oy
}
}
func (d *RGB) SetColor(c color.Color) {
r, g, b, a := c.RGBA()
d.r = uint16(r)
d.g = uint16(g)
d.b = uint16(b)
d.a = uint16(a)
}
func (d *RGB) Fill(r image.Rectangle) {
if d.a == 0 {
return
}
if d.mvxy&MV != 0 {
r.Min.X, r.Min.Y = r.Min.Y, r.Min.X
r.Max.X, r.Max.Y = r.Max.Y, r.Max.X
}
if d.mvxy&MX != 0 {
r.Max.X, r.Min.X = d.width-r.Min.X, d.width-r.Max.X
}
if d.mvxy&MY != 0 {
r.Max.Y, r.Min.Y = d.height-r.Min.Y, d.height-r.Max.Y
}
offset := r.Min.Y*d.stride + r.Min.X*3
maxi := offset + d.stride*r.Dy()
n := r.Dx() * 3
cr, cg, cb := uint(d.r), uint(d.g), uint(d.b)
a := 0xffff - uint(d.a)
for i := offset; i < maxi; i += d.stride {
for k, maxk := i, i+n; k < maxk; k += 3 {
pix := d.pix[k : k+3 : k+3] // see https://golang.org/issue/27857
r := uint(pix[0])
g := uint(pix[1])
b := uint(pix[2])
r = (r|r<<8)*a/0xffff + cr
g = (g|g<<8)*a/0xffff + cg
b = (b|b<<8)*a/0xffff + cb
pix[0] = uint8(r >> 8)
pix[1] = uint8(g >> 8)
pix[2] = uint8(b >> 8)
}
}
}