goaware.go

package main

// #cgo LDFLAGS: -lawj2k
// #include <j2k.h>
import "C"

import (
        "unsafe"
 	"log"
	"flag"
	"net/http"
 )

const MAX_PROGRESSION_LEVEL = uint(6)
const FULL_XFORM_FLAG = 0

func scaled_dimension(progression_level uint, dimension uint32) uint32 {
	scale_factor := uint(2)<<(progression_level-uint(1))
	return uint32(float32(dimension) / float32(scale_factor))
}

func desired_progression_level(x1, x2, y1, y2, width, height uint32) uint {
	level := MAX_PROGRESSION_LEVEL
	for ; level > 1 && width > scaled_dimension(level, x2 - x1) && height > scaled_dimension(level, y2 - y1); level-- {
	}
	return level
}

func TileHandler(w http.ResponseWriter, req *http.Request) {
	w.Header().Set("Content-Type", "image/jpeg")
	x1, y1, x2, y2 := uint32(100), uint32(100), uint32(500), uint32(500)
	width, height := uint32(400), uint32(400)
	//x1, y1, x2, y2 := uint32(1022), uint32(2046), uint32(1538), uint32(2562)
	//width, height := uint32(258), uint32(258)

	var obj unsafe.Pointer

	if err := C.aw_j2k_create(&obj); err != 0 {
		panic("create failed")
	}

	defer func() {
		C.aw_j2k_destroy(obj)
	}()

	if err := C.aw_j2k_set_input_image_file(obj, C.CString("0001.jp2")); err != 0 {
		panic("set input failed")
	}

	if err := C.aw_j2k_set_input_j2k_region_level(obj, C.ulong(x1), C.ulong(y1), C.ulong(x2), C.ulong(y2)); err != 0 {
	 	panic("set input region level failed")
	}

	if err := C.aw_j2k_set_output_com_image_size(obj, C.long(height), C.long(width), C.AW_J2K_PRESERVE_ASPECT_RATIO_NO_PAD); err != 0 {
		panic("set output size failed")
	}

	level := desired_progression_level(x1, x2, y1, y2, width, height)
        if err := C.aw_j2k_set_input_j2k_resolution_level(obj, C.int(level), C.int(FULL_XFORM_FLAG)); err != 0 {
		panic("set resolution level failed")
	}

	// var cols, rows, bpp, nChannels C.ulong
	// if err := C.aw_j2k_get_input_image_info(obj, &cols, &rows, &bpp, &nChannels); err != 0 {
	// 	panic(":|")
	// }
	// log.Println("cols:", cols, "rows:", rows)

	var image_buffer *C.uchar
	var image_buffer_length C.ulong
	if err := C.aw_j2k_get_output_image_type(obj, C.int(C.AW_J2K_FORMAT_JPG), &image_buffer, &image_buffer_length); err != 0 {
		log.Println("err:", err)
		panic("get output import failed")
	}
	//log.Println("buffer:", image_buffer, "length:", image_buffer_length)

	//aw_j2k_free(obj, image_buffer)

	w.Write(C.GoBytes(unsafe.Pointer(image_buffer), C.int(image_buffer_length)))
}

func main() {
	Address := flag.String("address", ":8888", "http service address")
	flag.Parse()

	http.Handle("/", http.HandlerFunc(TileHandler))

	if err := http.ListenAndServe(*Address, nil); err != nil {
		log.Print("ListenAndServe:", err)
	}
}