/
openjpeg.go
151 lines (126 loc) · 4.17 KB
/
openjpeg.go
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package main
// #cgo LDFLAGS: -lopenjp2
// #include <stdio.h>
// #include <openjpeg-2.0/openjpeg.h>
/*
static void info_callback(const char *msg, void *client_data) {
(void)client_data;
fprintf(stdout, "[INFO] %s", msg);
}
static void warning_callback(const char *msg, void *client_data) {
(void)client_data;
fprintf(stdout, "[WARNING] %s", msg);
}
static void error_callback(const char *msg, void *client_data) {
(void)client_data;
fprintf(stdout, "[ERROR] %s", msg);
}
void set_handlers(opj_codec_t * p_codec) {
opj_set_info_handler(p_codec, info_callback, 00);
opj_set_warning_handler(p_codec, warning_callback, 00);
opj_set_error_handler(p_codec, error_callback, 00);
}
*/
import "C"
import (
"errors"
"image"
"image/color"
"log"
"reflect"
"runtime"
"unsafe"
)
const MAX_PROGRESSION_LEVEL = uint(6)
func scaled_dimension(progression_level uint, dimension int) int {
scale_factor := uint(2) << (progression_level - uint(1))
return int(float32(dimension) / float32(scale_factor))
}
func desired_progression_level(r image.Rectangle, width, height int) uint {
level := MAX_PROGRESSION_LEVEL
for ; level > 0 && width > scaled_dimension(level, r.Dx()) && height > scaled_dimension(level, r.Dy()); level-- {
}
return level
}
func NewImageTile(filename string, r image.Rectangle, width, height int) (err error, tile *ImageTile) {
l_stream := C.opj_stream_create_default_file_stream_v3(C.CString(filename), 1)
if l_stream == nil {
return errors.New("failed to create stream"), nil
}
l_codec := C.opj_create_decompress(C.OPJ_CODEC_JP2)
var parameters C.opj_dparameters_t
C.opj_set_default_decoder_parameters(¶meters)
level := desired_progression_level(r, width, height)
log.Println("desired level:", level)
//(parameters).cp_reduce = C.OPJ_UINT32(level)
C.set_handlers(l_codec)
if err == nil && C.opj_setup_decoder(l_codec, ¶meters) == C.OPJ_FALSE {
err = errors.New("failed to setup decoder")
}
if err == nil && C.opj_set_decoded_resolution_factor(l_codec, C.OPJ_UINT32(level)) == C.OPJ_FALSE {
err = errors.New("failed to set decode resolution factor")
}
var img *C.opj_image_t
if err == nil && C.opj_read_header(l_stream, l_codec, &img) == C.OPJ_FALSE {
err = errors.New("failed to read the header")
}
if err == nil {
log.Println("num comps:", img.numcomps)
log.Println("x0:", img.x0, "x1:", img.x1, "y0:", img.y0, "y1:", img.y1)
}
if err == nil && C.opj_set_decode_area(l_codec, img, C.OPJ_INT32(r.Min.X), C.OPJ_INT32(r.Min.Y), C.OPJ_INT32(r.Max.X), C.OPJ_INT32(r.Max.Y)) == C.OPJ_FALSE {
err = errors.New("failed to set the decoded area")
}
if err == nil && C.opj_decode(l_codec, l_stream, img) == C.OPJ_FALSE {
err = errors.New("failed to decode image")
}
if err == nil && C.opj_end_decompress(l_codec, l_stream) == C.OPJ_FALSE {
err = errors.New("failed to decode image")
}
C.opj_stream_destroy_v3(l_stream)
if l_codec != nil {
C.opj_destroy_codec(l_codec)
}
if err == nil {
var comps []C.opj_image_comp_t
compsSlice := (*reflect.SliceHeader)((unsafe.Pointer(&comps)))
compsSlice.Cap = int(img.numcomps)
compsSlice.Len = int(img.numcomps)
compsSlice.Data = uintptr(unsafe.Pointer(img.comps))
bounds := image.Rect(0, 0, int(comps[0].w), int(comps[0].h))
var data []int32
dataSlice := (*reflect.SliceHeader)((unsafe.Pointer(&data)))
dataSlice.Cap = bounds.Dx() * bounds.Dy()
dataSlice.Len = bounds.Dx() * bounds.Dy()
dataSlice.Data = uintptr(unsafe.Pointer(comps[0].data))
tile = &ImageTile{data, bounds, bounds.Dx(), img}
runtime.SetFinalizer(tile, func(it *ImageTile) {
C.opj_image_destroy(it.img)
})
} else {
C.opj_image_destroy(img)
}
return
}
type ImageTile struct {
data []int32
bounds image.Rectangle
stride int
img *C.opj_image_t
}
func (p *ImageTile) ColorModel() color.Model {
return color.GrayModel
}
func (p *ImageTile) Bounds() image.Rectangle {
return p.bounds
}
func (p *ImageTile) At(x, y int) color.Color {
if !(image.Point{x, y}.In(p.bounds)) {
return color.Gray{}
}
index := p.PixOffset(x, y)
return color.Gray{uint8(p.data[index])}
}
func (p *ImageTile) PixOffset(x, y int) int {
return (y-p.bounds.Min.Y)*p.stride + (x-p.bounds.Min.X)*1
}