add stbi.loadf

[leyaocty]

hi neil,
would you please help to wrap C.stbi_loadf()? I tried to wrap it based on your pkg but failed...

[neilpa]

@leyaocty do you have an example image that you can share to test with?

[leyaocty]

@neilpa it works now, fyi
func Loadf(path string) (dt []float32, w int, h int, nre int, mfree func(), err error) {
// C.stbi_set_flip_vertically_on_load(1) // vertical reverse
cpath := C.CString(path)
defer C.free(unsafe.Pointer(cpath))

var x, y, nr C.int
data := C.stbi_loadf(cpath, &x, &y, &nr, 0)
if data == nil {
	msg := C.GoString(C.stbi_failure_reason())
	return nil, int(x), int(y), int(nr), nil, errors.New(msg)
}
var fs []float32
head := (*reflect.SliceHeader)(unsafe.Pointer(&fs))
head.Cap = 1
head.Len = head.Cap
head.Data = uintptr(unsafe.Pointer(data))
return fs, int(x), int(y), int(nr), func() { C.stbi_image_free(unsafe.Pointer(data)) }, nil

}