Golang image.Uniform類代碼示例

func drawGlyphOver(dst *image.RGBA, r Rectangle, src image.Uniform, mask *image.Alpha, mp Point) {
	x0, x1 := r.Min.X, r.Max.X
	y0, y1 := r.Min.Y, r.Max.Y
	cr, cg, cb, ca := src.RGBA()
	for y, my := y0, mp.Y; y != y1; y, my = y+1, my+1 {
		dpix := dst.Pixel[y]
		mpix := mask.Pixel[my]
		for x, mx := x0, mp.X; x != x1; x, mx = x+1, mx+1 {
			ma := uint32(mpix[mx].A)
			if ma == 0 {
				continue
			}
			ma |= ma << 8
			rgba := dpix[x]
			dr := uint32(rgba.R)
			dg := uint32(rgba.G)
			db := uint32(rgba.B)
			da := uint32(rgba.A)
			// The 0x101 is here for the same reason as in drawRGBA.
			a := (m - (ca * ma / m)) * 0x101
			dr = (dr*a + cr*ma) / m
			dg = (dg*a + cg*ma) / m
			db = (db*a + cb*ma) / m
			da = (da*a + ca*ma) / m
			dpix[x] = color.RGBA{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
		}
	}
}

func drawGlyphOver(dst *image.RGBA, r image.Rectangle, src *image.Uniform, mask *image.Alpha, mp image.Point) {
	i0 := dst.PixOffset(r.Min.X, r.Min.Y)
	i1 := i0 + r.Dx()*4
	mi0 := mask.PixOffset(mp.X, mp.Y)
	sr, sg, sb, sa := src.RGBA()
	for y, my := r.Min.Y, mp.Y; y != r.Max.Y; y, my = y+1, my+1 {
		for i, mi := i0, mi0; i < i1; i, mi = i+4, mi+1 {
			ma := uint32(mask.Pix[mi])
			if ma == 0 {
				continue
			}
			ma |= ma << 8

			dr := uint32(dst.Pix[i+0])
			dg := uint32(dst.Pix[i+1])
			db := uint32(dst.Pix[i+2])
			da := uint32(dst.Pix[i+3])

			// The 0x101 is here for the same reason as in drawRGBA.
			a := (m - (sa * ma / m)) * 0x101

			dst.Pix[i+0] = uint8((dr*a + sr*ma) / m >> 8)
			dst.Pix[i+1] = uint8((dg*a + sg*ma) / m >> 8)
			dst.Pix[i+2] = uint8((db*a + sb*ma) / m >> 8)
			dst.Pix[i+3] = uint8((da*a + sa*ma) / m >> 8)
		}
		i0 += dst.Stride
		i1 += dst.Stride
		mi0 += mask.Stride
	}
}

func drawFillOver(dst *image.RGBA, r Rectangle, src image.Uniform) {
	cr, cg, cb, ca := src.RGBA()
	// The 0x101 is here for the same reason as in drawRGBA.
	a := (m - ca) * 0x101
	x0, x1 := r.Min.X, r.Max.X
	y0, y1 := r.Min.Y, r.Max.Y
	for y := y0; y != y1; y++ {
		dpix := dst.Pixel[y]
		for x := x0; x != x1; x++ {
			rgba := dpix[x]
			dr := (uint32(rgba.R)*a)/m + cr
			dg := (uint32(rgba.G)*a)/m + cg
			db := (uint32(rgba.B)*a)/m + cb
			da := (uint32(rgba.A)*a)/m + ca
			dpix[x] = color.RGBA{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
		}
	}
}

func drawFillSrc(dst *image.RGBA, r image.Rectangle, src *image.Uniform) {
	sr, sg, sb, sa := src.RGBA()
	// The built-in copy function is faster than a straightforward for loop to fill the destination with
	// the color, but copy requires a slice source. We therefore use a for loop to fill the first row, and
	// then use the first row as the slice source for the remaining rows.
	i0 := dst.PixOffset(r.Min.X, r.Min.Y)
	i1 := i0 + r.Dx()*4
	for i := i0; i < i1; i += 4 {
		dst.Pix[i+0] = uint8(sr >> 8)
		dst.Pix[i+1] = uint8(sg >> 8)
		dst.Pix[i+2] = uint8(sb >> 8)
		dst.Pix[i+3] = uint8(sa >> 8)
	}
	firstRow := dst.Pix[i0:i1]
	for y := r.Min.Y + 1; y < r.Max.Y; y++ {
		i0 += dst.Stride
		i1 += dst.Stride
		copy(dst.Pix[i0:i1], firstRow)
	}
}

func drawFillSrc(dst *image.RGBA, r Rectangle, src image.Uniform) {
	if r.Dy() < 1 {
		return
	}
	cr, cg, cb, ca := src.RGBA()
	color := color.RGBA{uint8(cr >> 8), uint8(cg >> 8), uint8(cb >> 8), uint8(ca >> 8)}
	// The built-in copy function is faster than a straightforward for loop to fill the destination with
	// the color, but copy requires a slice source. We therefore use a for loop to fill the first row, and
	// then use the first row as the slice source for the remaining rows.
	dx0, dx1 := r.Min.X, r.Max.X
	dy0, dy1 := r.Min.Y, r.Max.Y
	firstRow := dst.Pixel[dy0]
	for x := dx0; x < dx1; x++ {
		firstRow[x] = color
	}
	copySrc := firstRow[dx0:dx1]
	for y := dy0 + 1; y < dy1; y++ {
		copy(dst.Pixel[y][dx0:dx1], copySrc)
	}
}

func drawFillOver(dst *image.RGBA, r image.Rectangle, src *image.Uniform) {
	sr, sg, sb, sa := src.RGBA()
	// The 0x101 is here for the same reason as in drawRGBA.
	a := (m - sa) * 0x101
	i0 := dst.PixOffset(r.Min.X, r.Min.Y)
	i1 := i0 + r.Dx()*4
	for y := r.Min.Y; y != r.Max.Y; y++ {
		for i := i0; i < i1; i += 4 {
			dr := uint32(dst.Pix[i+0])
			dg := uint32(dst.Pix[i+1])
			db := uint32(dst.Pix[i+2])
			da := uint32(dst.Pix[i+3])

			dst.Pix[i+0] = uint8((dr*a/m + sr) >> 8)
			dst.Pix[i+1] = uint8((dg*a/m + sg) >> 8)
			dst.Pix[i+2] = uint8((db*a/m + sb) >> 8)
			dst.Pix[i+3] = uint8((da*a/m + sa) >> 8)
		}
		i0 += dst.Stride
		i1 += dst.Stride
	}
}

func drawFillOver(dst *image.RGBA, r image.Rectangle, src *image.Uniform) {
	sr, sg, sb, sa := src.RGBA()
	// The 0x101 is here for the same reason as in drawRGBA.
	a := (m - sa) * 0x101
	i0 := dst.PixOffset(r.Min.X, r.Min.Y)
	i1 := i0 + r.Dx()*4
	for y := r.Min.Y; y != r.Max.Y; y++ {
		for i := i0; i < i1; i += 4 {
			dr := &dst.Pix[i+0]
			dg := &dst.Pix[i+1]
			db := &dst.Pix[i+2]
			da := &dst.Pix[i+3]

			*dr = uint8((uint32(*dr)*a/m + sr) >> 8)
			*dg = uint8((uint32(*dg)*a/m + sg) >> 8)
			*db = uint8((uint32(*db)*a/m + sb) >> 8)
			*da = uint8((uint32(*da)*a/m + sa) >> 8)
		}
		i0 += dst.Stride
		i1 += dst.Stride
	}
}