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package imaging
import (
"image"
"image/color"
"math"
)
// FlipH flips the image horizontally (from left to right) and returns the transformed image.
func FlipH(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.w
dstH := src.h
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcY := dstY
src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
})
return dst
}
// FlipV flips the image vertically (from top to bottom) and returns the transformed image.
func FlipV(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.w
dstH := src.h
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcY := dstH - dstY - 1
src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
}
})
return dst
}
// Transpose flips the image horizontally and rotates 90 degrees counter-clockwise.
func Transpose(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcX := dstY
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
}
})
return dst
}
// Transverse flips the image vertically and rotates 90 degrees counter-clockwise.
func Transverse(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcX := dstH - dstY - 1
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
})
return dst
}
// Rotate90 rotates the image 90 degrees counter-clockwise and returns the transformed image.
func Rotate90(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcX := dstH - dstY - 1
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
}
})
return dst
}
// Rotate180 rotates the image 180 degrees counter-clockwise and returns the transformed image.
func Rotate180(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.w
dstH := src.h
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcY := dstH - dstY - 1
src.scan(0, srcY, src.w, srcY+1, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
})
return dst
}
// Rotate270 rotates the image 270 degrees counter-clockwise and returns the transformed image.
func Rotate270(img image.Image) *image.NRGBA {
src := newScanner(img)
dstW := src.h
dstH := src.w
rowSize := dstW * 4
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
i := dstY * dst.Stride
srcX := dstY
src.scan(srcX, 0, srcX+1, src.h, dst.Pix[i:i+rowSize])
reverse(dst.Pix[i : i+rowSize])
}
})
return dst
}
// Rotate rotates an image by the given angle counter-clockwise .
// The angle parameter is the rotation angle in degrees.
// The bgColor parameter specifies the color of the uncovered zone after the rotation.
func Rotate(img image.Image, angle float64, bgColor color.Color) *image.NRGBA {
angle = angle - math.Floor(angle/360)*360
switch angle {
case 0:
return Clone(img)
case 90:
return Rotate90(img)
case 180:
return Rotate180(img)
case 270:
return Rotate270(img)
}
src := toNRGBA(img)
srcW := src.Bounds().Max.X
srcH := src.Bounds().Max.Y
dstW, dstH := rotatedSize(srcW, srcH, angle)
dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
if dstW <= 0 || dstH <= 0 {
return dst
}
srcXOff := float64(srcW)/2 - 0.5
srcYOff := float64(srcH)/2 - 0.5
dstXOff := float64(dstW)/2 - 0.5
dstYOff := float64(dstH)/2 - 0.5
bgColorNRGBA := color.NRGBAModel.Convert(bgColor).(color.NRGBA)
sin, cos := math.Sincos(math.Pi * angle / 180)
parallel(0, dstH, func(ys <-chan int) {
for dstY := range ys {
for dstX := 0; dstX < dstW; dstX++ {
xf, yf := rotatePoint(float64(dstX)-dstXOff, float64(dstY)-dstYOff, sin, cos)
xf, yf = xf+srcXOff, yf+srcYOff
interpolatePoint(dst, dstX, dstY, src, xf, yf, bgColorNRGBA)
}
}
})
return dst
}
func rotatePoint(x, y, sin, cos float64) (float64, float64) {
return x*cos - y*sin, x*sin + y*cos
}
func rotatedSize(w, h int, angle float64) (int, int) {
if w <= 0 || h <= 0 {
return 0, 0
}
sin, cos := math.Sincos(math.Pi * angle / 180)
x1, y1 := rotatePoint(float64(w-1), 0, sin, cos)
x2, y2 := rotatePoint(float64(w-1), float64(h-1), sin, cos)
x3, y3 := rotatePoint(0, float64(h-1), sin, cos)
minx := math.Min(x1, math.Min(x2, math.Min(x3, 0)))
maxx := math.Max(x1, math.Max(x2, math.Max(x3, 0)))
miny := math.Min(y1, math.Min(y2, math.Min(y3, 0)))
maxy := math.Max(y1, math.Max(y2, math.Max(y3, 0)))
neww := maxx - minx + 1
if neww-math.Floor(neww) > 0.1 {
neww++
}
newh := maxy - miny + 1
if newh-math.Floor(newh) > 0.1 {
newh++
}
return int(neww), int(newh)
}
func interpolatePoint(dst *image.NRGBA, dstX, dstY int, src *image.NRGBA, xf, yf float64, bgColor color.NRGBA) {
j := dstY*dst.Stride + dstX*4
d := dst.Pix[j : j+4 : j+4]
x0 := int(math.Floor(xf))
y0 := int(math.Floor(yf))
bounds := src.Bounds()
if !image.Pt(x0, y0).In(image.Rect(bounds.Min.X-1, bounds.Min.Y-1, bounds.Max.X, bounds.Max.Y)) {
d[0] = bgColor.R
d[1] = bgColor.G
d[2] = bgColor.B
d[3] = bgColor.A
return
}
xq := xf - float64(x0)
yq := yf - float64(y0)
points := [4]image.Point{
{x0, y0},
{x0 + 1, y0},
{x0, y0 + 1},
{x0 + 1, y0 + 1},
}
weights := [4]float64{
(1 - xq) * (1 - yq),
xq * (1 - yq),
(1 - xq) * yq,
xq * yq,
}
var r, g, b, a float64
for i := 0; i < 4; i++ {
p := points[i]
w := weights[i]
if p.In(bounds) {
i := p.Y*src.Stride + p.X*4
s := src.Pix[i : i+4 : i+4]
wa := float64(s[3]) * w
r += float64(s[0]) * wa
g += float64(s[1]) * wa
b += float64(s[2]) * wa
a += wa
} else {
wa := float64(bgColor.A) * w
r += float64(bgColor.R) * wa
g += float64(bgColor.G) * wa
b += float64(bgColor.B) * wa
a += wa
}
}
if a != 0 {
aInv := 1 / a
d[0] = clamp(r * aInv)
d[1] = clamp(g * aInv)
d[2] = clamp(b * aInv)
d[3] = clamp(a)
}
}
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