func main() {
str := "Hello World"
cstr := C.CString(str)
defer free(cstr)
dup := C.strdup(C.CString(str))
defer free(dup)
gostr := C.GoString(dup)
fmt.Println(gostr)
}
func main() {
// a go string
go1 := "hello C"
// allocate in C and convert from Go representation to C representation
c1 := C.CString(go1)
// go string can now be garbage collected
go1 = ""
// strdup, per task. this calls the function in the C library.
c2 := C.strdup(c1)
// free the source C string. again, this is free() in the C library.
C.free(unsafe.Pointer(c1))
// create a new Go string from the C copy
go2 := C.GoString(c2)
// free the C copy
C.free(unsafe.Pointer(c2))
// demonstrate we have string contents intact
fmt.Println(go2)
}
// Encode writes the image to the given io.Writer, encoding
// it according to the info parameter. Please, see the
// Info type for the available encoding options.
func (im *Image) Encode(w io.Writer, info *Info) error {
var ex C.ExceptionInfo
C.GetExceptionInfo(&ex)
defer C.DestroyExceptionInfo(&ex)
if info == nil {
info = NewInfo()
}
/* ImageToBlob copies the format from the image into
the image info. Overwrite if required and then restore
*/
im.mu.Lock()
var format *C.char
copied := false
if info.info.magick[0] != 0 {
copied = true
if im.image.magick[0] != 0 {
format = C.strdup(&im.image.magick[0])
}
C.strncpy(&im.image.magick[0], &info.info.magick[0], C.MaxTextExtent)
}
var s C.size_t
mem := imageToBlob(info, im, &s, &ex)
if copied {
/* Restore image format */
if format != nil {
C.strncpy(&im.image.magick[0], format, C.MaxTextExtent)
C.free(unsafe.Pointer(format))
} else {
C.memset(unsafe.Pointer(&im.image.magick[0]), 0, C.MaxTextExtent)
}
}
im.mu.Unlock()
if mem == nil {
return exError(&ex, "encoding")
}
b := goBytes(mem, int(s))
w.Write(b)
C.free(mem)
return nil
}