go-fitz/fitz.go

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2023-10-17 15:51:53 +00:00
// Package fitz provides wrapper for the [MuPDF](http://mupdf.com/) fitz library
// that can extract pages from PDF and EPUB documents as images, text, html or svg.
package fitz
/*
#include <mupdf/fitz.h>
#include <stdlib.h>
const char *fz_version = FZ_VERSION;
fz_document *open_document(fz_context *ctx, const char *filename) {
fz_document *doc;
fz_try(ctx) {
doc = fz_open_document(ctx, filename);
}
fz_catch(ctx) {
return NULL;
}
return doc;
}
fz_document *open_document_with_stream(fz_context *ctx, const char *magic, fz_stream *stream) {
fz_document *doc;
fz_try(ctx) {
doc = fz_open_document_with_stream(ctx, magic, stream);
}
fz_catch(ctx) {
return NULL;
}
return doc;
}
*/
import "C"
import (
"errors"
"image"
"io"
"os"
"path/filepath"
"sync"
"unsafe"
)
// Errors.
var (
ErrNoSuchFile = errors.New("fitz: no such file")
ErrCreateContext = errors.New("fitz: cannot create context")
ErrOpenDocument = errors.New("fitz: cannot open document")
ErrOpenMemory = errors.New("fitz: cannot open memory")
ErrPageMissing = errors.New("fitz: page missing")
ErrCreatePixmap = errors.New("fitz: cannot create pixmap")
ErrPixmapSamples = errors.New("fitz: cannot get pixmap samples")
ErrNeedsPassword = errors.New("fitz: document needs password")
ErrLoadOutline = errors.New("fitz: cannot load outline")
)
// Document represents fitz document.
type Document struct {
ctx *C.struct_fz_context
data []byte // binds data to the Document lifecycle avoiding premature GC
doc *C.struct_fz_document
mtx sync.Mutex
stream *C.fz_stream
}
// Outline type.
type Outline struct {
// Hierarchy level of the entry (starting from 1).
Level int
// Title of outline item.
Title string
// Destination in the document to be displayed when this outline item is activated.
URI string
// The page number of an internal link.
Page int
// Top.
Top float64
}
// Link type.
type Link struct {
URI string
}
// New returns new fitz document.
func New(filename string) (f *Document, err error) {
f = &Document{}
filename, err = filepath.Abs(filename)
if err != nil {
return
}
if _, e := os.Stat(filename); e != nil {
err = ErrNoSuchFile
return
}
f.ctx = (*C.struct_fz_context)(unsafe.Pointer(C.fz_new_context_imp(nil, nil, C.FZ_STORE_UNLIMITED, C.fz_version)))
if f.ctx == nil {
err = ErrCreateContext
return
}
C.fz_register_document_handlers(f.ctx)
cfilename := C.CString(filename)
defer C.free(unsafe.Pointer(cfilename))
f.doc = C.open_document(f.ctx, cfilename)
if f.doc == nil {
err = ErrOpenDocument
return
}
ret := C.fz_needs_password(f.ctx, f.doc)
v := int(ret) != 0
if v {
err = ErrNeedsPassword
}
return
}
// NewFromMemory returns new fitz document from byte slice.
func NewFromMemory(b []byte) (f *Document, err error) {
f = &Document{}
f.ctx = (*C.struct_fz_context)(unsafe.Pointer(C.fz_new_context_imp(nil, nil, C.FZ_STORE_UNLIMITED, C.fz_version)))
if f.ctx == nil {
err = ErrCreateContext
return
}
C.fz_register_document_handlers(f.ctx)
stream := C.fz_open_memory(f.ctx, (*C.uchar)(&b[0]), C.size_t(len(b)))
f.stream = C.fz_keep_stream(f.ctx, stream)
if f.stream == nil {
err = ErrOpenMemory
return
}
magic := contentType(b)
if magic == "" {
err = ErrOpenMemory
return
}
f.data = b
cmagic := C.CString(magic)
defer C.free(unsafe.Pointer(cmagic))
f.doc = C.open_document_with_stream(f.ctx, cmagic, f.stream)
if f.doc == nil {
err = ErrOpenDocument
}
ret := C.fz_needs_password(f.ctx, f.doc)
v := int(ret) != 0
if v {
err = ErrNeedsPassword
}
return
}
// NewFromReader returns new fitz document from io.Reader.
func NewFromReader(r io.Reader) (f *Document, err error) {
b, e := io.ReadAll(r)
if e != nil {
err = e
return
}
f, err = NewFromMemory(b)
return
}
// NumPage returns total number of pages in document.
func (f *Document) NumPage() int {
return int(C.fz_count_pages(f.ctx, f.doc))
}
// Image returns image for given page number.
func (f *Document) Image(pageNumber int) (image.Image, error) {
return f.ImageDPI(pageNumber, 300.0)
}
// ImageDPI returns image for given page number and DPI.
func (f *Document) ImageDPI(pageNumber int, dpi float64) (image.Image, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
img := image.RGBA{}
if pageNumber >= f.NumPage() {
return nil, ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
var bounds C.fz_rect
bounds = C.fz_bound_page(f.ctx, page)
var ctm C.fz_matrix
ctm = C.fz_scale(C.float(dpi/72), C.float(dpi/72))
var bbox C.fz_irect
bounds = C.fz_transform_rect(bounds, ctm)
bbox = C.fz_round_rect(bounds)
pixmap := C.fz_new_pixmap_with_bbox(f.ctx, C.fz_device_rgb(f.ctx), bbox, nil, 1)
if pixmap == nil {
return nil, ErrCreatePixmap
}
C.fz_clear_pixmap_with_value(f.ctx, pixmap, C.int(0xff))
//defer C.fz_drop_pixmap(f.ctx, pixmap)
device := C.fz_new_draw_device(f.ctx, ctm, pixmap)
C.fz_enable_device_hints(f.ctx, device, C.FZ_NO_CACHE)
defer C.fz_drop_device(f.ctx, device)
drawMatrix := C.fz_identity
C.fz_run_page(f.ctx, page, device, drawMatrix, nil)
C.fz_close_device(f.ctx, device)
pixels := C.fz_pixmap_samples(f.ctx, pixmap)
if pixels == nil {
return nil, ErrPixmapSamples
}
defer C.free(unsafe.Pointer(pixels))
img.Pix = C.GoBytes(unsafe.Pointer(pixels), C.int(4*bbox.x1*bbox.y1))
img.Rect = image.Rect(int(bbox.x0), int(bbox.y0), int(bbox.x1), int(bbox.y1))
img.Stride = 4 * img.Rect.Max.X
return &img, nil
}
// ImagePNG returns image for given page number as PNG bytes.
func (f *Document) ImagePNG(pageNumber int, dpi float64) ([]byte, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
if pageNumber >= f.NumPage() {
return nil, ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
var bounds C.fz_rect
bounds = C.fz_bound_page(f.ctx, page)
var ctm C.fz_matrix
ctm = C.fz_scale(C.float(dpi/72), C.float(dpi/72))
var bbox C.fz_irect
bounds = C.fz_transform_rect(bounds, ctm)
bbox = C.fz_round_rect(bounds)
pixmap := C.fz_new_pixmap_with_bbox(f.ctx, C.fz_device_rgb(f.ctx), bbox, nil, 1)
if pixmap == nil {
return nil, ErrCreatePixmap
}
C.fz_clear_pixmap_with_value(f.ctx, pixmap, C.int(0xff))
//defer C.fz_drop_pixmap(f.ctx, pixmap)
device := C.fz_new_draw_device(f.ctx, ctm, pixmap)
C.fz_enable_device_hints(f.ctx, device, C.FZ_NO_CACHE)
defer C.fz_drop_device(f.ctx, device)
drawMatrix := C.fz_identity
C.fz_run_page(f.ctx, page, device, drawMatrix, nil)
C.fz_close_device(f.ctx, device)
buf := C.fz_new_buffer_from_pixmap_as_png(f.ctx, pixmap, C.fz_default_color_params)
defer C.fz_drop_buffer(f.ctx, buf)
size := C.fz_buffer_storage(f.ctx, buf, nil)
str := C.GoStringN(C.fz_string_from_buffer(f.ctx, buf), C.int(size))
return []byte(str), nil
}
// Links returns slice of links for given page number.
func (f *Document) Links(pageNumber int) ([]Link, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
if pageNumber >= f.NumPage() {
return nil, ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
links := C.fz_load_links(f.ctx, page)
defer C.fz_drop_link(f.ctx, links)
linkCount := 0
for currLink := links; currLink != nil; currLink = currLink.next {
linkCount++
}
if linkCount == 0 {
return nil, nil
}
gLinks := make([]Link, linkCount)
currLink := links
for i := 0; i < linkCount; i++ {
gLinks[i] = Link{
URI: C.GoString(currLink.uri),
}
currLink = currLink.next
}
return gLinks, nil
}
// Text returns text for given page number.
func (f *Document) Text(pageNumber int) (string, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
if pageNumber >= f.NumPage() {
return "", ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
var bounds C.fz_rect
bounds = C.fz_bound_page(f.ctx, page)
var ctm C.fz_matrix
ctm = C.fz_scale(C.float(72.0/72), C.float(72.0/72))
text := C.fz_new_stext_page(f.ctx, bounds)
defer C.fz_drop_stext_page(f.ctx, text)
var opts C.fz_stext_options
opts.flags = 0
device := C.fz_new_stext_device(f.ctx, text, &opts)
C.fz_enable_device_hints(f.ctx, device, C.FZ_NO_CACHE)
defer C.fz_drop_device(f.ctx, device)
var cookie C.fz_cookie
C.fz_run_page(f.ctx, page, device, ctm, &cookie)
C.fz_close_device(f.ctx, device)
buf := C.fz_new_buffer_from_stext_page(f.ctx, text)
defer C.fz_drop_buffer(f.ctx, buf)
str := C.GoString(C.fz_string_from_buffer(f.ctx, buf))
return str, nil
}
// HTML returns html for given page number.
func (f *Document) HTML(pageNumber int, header bool) (string, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
if pageNumber >= f.NumPage() {
return "", ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
var bounds C.fz_rect
bounds = C.fz_bound_page(f.ctx, page)
var ctm C.fz_matrix
ctm = C.fz_scale(C.float(72.0/72), C.float(72.0/72))
text := C.fz_new_stext_page(f.ctx, bounds)
defer C.fz_drop_stext_page(f.ctx, text)
var opts C.fz_stext_options
opts.flags = C.FZ_STEXT_PRESERVE_IMAGES
device := C.fz_new_stext_device(f.ctx, text, &opts)
C.fz_enable_device_hints(f.ctx, device, C.FZ_NO_CACHE)
defer C.fz_drop_device(f.ctx, device)
var cookie C.fz_cookie
C.fz_run_page(f.ctx, page, device, ctm, &cookie)
C.fz_close_device(f.ctx, device)
buf := C.fz_new_buffer(f.ctx, 1024)
defer C.fz_drop_buffer(f.ctx, buf)
out := C.fz_new_output_with_buffer(f.ctx, buf)
defer C.fz_drop_output(f.ctx, out)
if header {
C.fz_print_stext_header_as_html(f.ctx, out)
}
C.fz_print_stext_page_as_html(f.ctx, out, text, C.int(pageNumber))
if header {
C.fz_print_stext_trailer_as_html(f.ctx, out)
}
str := C.GoString(C.fz_string_from_buffer(f.ctx, buf))
return str, nil
}
// SVG returns svg document for given page number.
func (f *Document) SVG(pageNumber int) (string, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
if pageNumber >= f.NumPage() {
return "", ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
var bounds C.fz_rect
bounds = C.fz_bound_page(f.ctx, page)
var ctm C.fz_matrix
ctm = C.fz_scale(C.float(72.0/72), C.float(72.0/72))
bounds = C.fz_transform_rect(bounds, ctm)
buf := C.fz_new_buffer(f.ctx, 1024)
defer C.fz_drop_buffer(f.ctx, buf)
out := C.fz_new_output_with_buffer(f.ctx, buf)
defer C.fz_drop_output(f.ctx, out)
device := C.fz_new_svg_device(f.ctx, out, bounds.x1-bounds.x0, bounds.y1-bounds.y0, C.FZ_SVG_TEXT_AS_PATH, 1)
C.fz_enable_device_hints(f.ctx, device, C.FZ_NO_CACHE)
defer C.fz_drop_device(f.ctx, device)
var cookie C.fz_cookie
C.fz_run_page(f.ctx, page, device, ctm, &cookie)
C.fz_close_device(f.ctx, device)
str := C.GoString(C.fz_string_from_buffer(f.ctx, buf))
return str, nil
}
// ToC returns the table of contents (also known as outline).
func (f *Document) ToC() ([]Outline, error) {
data := make([]Outline, 0)
outline := C.fz_load_outline(f.ctx, f.doc)
if outline == nil {
return nil, ErrLoadOutline
}
defer C.fz_drop_outline(f.ctx, outline)
var walk func(outline *C.fz_outline, level int)
walk = func(outline *C.fz_outline, level int) {
for outline != nil {
res := Outline{}
res.Level = level
res.Title = C.GoString(outline.title)
res.URI = C.GoString(outline.uri)
res.Page = int(outline.page.page)
res.Top = float64(outline.y)
data = append(data, res)
if outline.down != nil {
walk(outline.down, level+1)
}
outline = outline.next
}
}
walk(outline, 1)
return data, nil
}
// Metadata returns the map with standard metadata.
func (f *Document) Metadata() map[string]string {
data := make(map[string]string)
lookup := func(key string) string {
ckey := C.CString(key)
defer C.free(unsafe.Pointer(ckey))
buf := make([]byte, 256)
C.fz_lookup_metadata(f.ctx, f.doc, ckey, (*C.char)(unsafe.Pointer(&buf[0])), C.int(len(buf)))
return string(buf)
}
data["format"] = lookup("format")
data["encryption"] = lookup("encryption")
data["title"] = lookup("info:Title")
data["author"] = lookup("info:Author")
data["subject"] = lookup("info:Subject")
data["keywords"] = lookup("info:Keywords")
data["creator"] = lookup("info:Creator")
data["producer"] = lookup("info:Producer")
data["creationDate"] = lookup("info:CreationDate")
data["modDate"] = lookup("info:modDate")
return data
}
// Bound gives the Bounds of a given Page in the document.
func (f *Document) Bound(pageNumber int) (image.Rectangle, error) {
f.mtx.Lock()
defer f.mtx.Unlock()
if pageNumber >= f.NumPage() {
return image.Rectangle{}, ErrPageMissing
}
page := C.fz_load_page(f.ctx, f.doc, C.int(pageNumber))
defer C.fz_drop_page(f.ctx, page)
var bounds C.fz_rect
bounds = C.fz_bound_page(f.ctx, page)
return image.Rect(int(bounds.x0), int(bounds.y0), int(bounds.x1), int(bounds.y1)), nil
}
// Close closes the underlying fitz document.
func (f *Document) Close() error {
if f.stream != nil {
C.fz_drop_stream(f.ctx, f.stream)
}
C.fz_drop_document(f.ctx, f.doc)
C.fz_drop_context(f.ctx)
f.data = nil
return nil
}