func bilinear(im image.Image, scalex float32, scaley float32) (imageng, os.Error) {
if scalex >= 1.0 && scaley >= 1.0 {
ws := im.Bounds().Dx()
hs := im.Bounds().Dy()
wd := int(scalex * float32(ws))
hd := int(scaley * float32(hs))
scaled := imgType(im, wd, hd)
var c00, c01, c10, c11 image.RGBA64Color
var x0, x1, xs, ys, y0, y1 uint32
var r, g, b, a uint32
var r00, r11, r10, r01, g00, g11, g10, g01, b00, b11, b10, b01, a00, a11, a10, a01 uint32
var i, j uint32
ys = 1
for y := 1; y < hs; y++ {
x0 = 0
x1 = 0 // not so sure
xs = 1
y0 = y1
y1 = uint32(float32(ys) * scaley)
c00 = image.RGBA64ColorModel.Convert(im.At(0, int(ys-1))).(image.RGBA64Color)
c01 = image.RGBA64ColorModel.Convert(im.At(0, int(ys))).(image.RGBA64Color)
c10 = image.RGBA64ColorModel.Convert(im.At(1, int(ys-1))).(image.RGBA64Color)
c11 = image.RGBA64ColorModel.Convert(im.At(1, int(ys))).(image.RGBA64Color)
for x := 1; x < ws; x++ {
x0 = x1
x1 = uint32(float32(xs) * scalex)
c00 = c10
c01 = c11
c10 = image.RGBA64ColorModel.Convert(im.At(int(xs), int(ys-1))).(image.RGBA64Color)
c11 = image.RGBA64ColorModel.Convert(im.At(int(xs), int(ys))).(image.RGBA64Color)
for j = y0; j < y1; j++ {
for i = x0; i < x1; i++ {
r00, g00, b00, a00 = c00.RGBA()
r01, g01, b01, a01 = c01.RGBA()
r10, g10, b10, a10 = c10.RGBA()
r11, g11, b11, a11 = c11.RGBA()
// print(r00, ", ", r01, ", ", r10, ", ", r11, "\n")
r = ((r00*(x1-i)+r10*(i-x0))*(y1-j) +
(r01*(x1-i)+r11*(i-x0))*(j-y0)) /
((x1 - x0) * (y1 - y0))
g = ((g00*(x1-i)+g10*(i-x0))*(y1-j) +
(g01*(x1-i)+g11*(i-x0))*(j-y0)) /
((x1 - x0) * (y1 - y0))
b = ((b00*(x1-i)+b10*(i-x0))*(y1-j) +
(b01*(x1-i)+b11*(i-x0))*(j-y0)) /
((x1 - x0) * (y1 - y0))
a = ((a00*(x1-i)+a10*(i-x0))*(y1-j) +
(a01*(x1-i)+a11*(i-x0))*(j-y0)) /
((x1 - x0) * (y1 - y0))
scaled.Set(int(i), int(j),
convertColor(im, image.RGBA64Color{uint16(r), uint16(g), uint16(b), uint16(a)}))
}
}
xs++
}
ys++
}
return scaled, nil
}
return nil, os.NewError("no scaling down")
}
