gtsocial-umbx

transform.go (6746B)

---

 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)
 	}
 }