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-rw-r--r--bk_pdf.c467
1 files changed, 467 insertions, 0 deletions
diff --git a/bk_pdf.c b/bk_pdf.c
new file mode 100644
index 0000000..44f7486
--- /dev/null
+++ b/bk_pdf.c
@@ -0,0 +1,467 @@
+/*
+ * PDF backend for Halibut
+ */
+
+#include <assert.h>
+#include "halibut.h"
+#include "paper.h"
+
+#define TREE_BRANCH 2 /* max branching factor in page tree */
+
+paragraph *pdf_config_filename(char *filename)
+{
+ paragraph *p;
+ wchar_t *ufilename, *up;
+ int len;
+
+ p = mknew(paragraph);
+ memset(p, 0, sizeof(*p));
+ p->type = para_Config;
+ p->next = NULL;
+ p->fpos.filename = "<command line>";
+ p->fpos.line = p->fpos.col = -1;
+
+ ufilename = ufroma_dup(filename);
+ len = ustrlen(ufilename) + 2 + lenof(L"pdf-filename");
+ p->keyword = mknewa(wchar_t, len);
+ up = p->keyword;
+ ustrcpy(up, L"pdf-filename");
+ up = uadv(up);
+ ustrcpy(up, ufilename);
+ up = uadv(up);
+ *up = L'\0';
+ assert(up - p->keyword < len);
+ sfree(ufilename);
+
+ return p;
+}
+
+typedef struct object_Tag object;
+typedef struct objlist_Tag objlist;
+
+struct object_Tag {
+ objlist *list;
+ object *next;
+ int number;
+ rdstringc main, stream;
+ int size, fileoff;
+ char *final;
+};
+
+struct objlist_Tag {
+ int number;
+ object *head, *tail;
+};
+
+static object *new_object(objlist *list);
+static void objtext(object *o, char const *text);
+static void objstream(object *o, char const *text);
+static void objref(object *o, object *dest);
+
+static void make_pages_node(object *node, object *parent, page_data *first,
+ page_data *last, object *resources);
+
+void pdf_backend(paragraph *sourceform, keywordlist *keywords,
+ indexdata *idx, void *vdoc) {
+ document *doc = (document *)vdoc;
+ int font_index;
+ font_encoding *fe;
+ page_data *page;
+ int pageno;
+ FILE *fp;
+ char *filename;
+ paragraph *p;
+ objlist olist;
+ object *o, *cat, *outlines, *pages, *resources;
+ int fileoff;
+
+ IGNORE(keywords);
+ IGNORE(idx);
+
+ filename = dupstr("output.pdf");
+ for (p = sourceform; p; p = p->next) {
+ p->private_data = NULL;
+ if (p->type == para_Config && p->parent) {
+ if (!ustricmp(p->keyword, L"pdf-filename")) {
+ sfree(filename);
+ filename = utoa_dup(uadv(p->keyword));
+ }
+ }
+ }
+
+ olist.head = olist.tail = NULL;
+ olist.number = 1;
+
+ cat = new_object(&olist);
+ outlines = new_object(&olist);
+ pages = new_object(&olist);
+ resources = new_object(&olist);
+
+ /*
+ * We currently don't support outlines, so here's a null
+ * outlines dictionary.
+ */
+ objtext(outlines, "<<\n/Type Outlines\n/Count 0\n>>\n");
+
+ /*
+ * The catalogue just contains references to the outlines and
+ * pages objects.
+ */
+ objtext(cat, "<<\n/Type /Catalog\n/Outlines ");
+ objref(cat, outlines);
+ objtext(cat, "\n/Pages ");
+ objref(cat, pages);
+ objtext(cat, "\n>>\n");
+
+ /*
+ * Set up the resources dictionary, which mostly means
+ * providing all the font objects and names to call them by.
+ */
+ font_index = 0;
+ objtext(resources, "<<\n/Font <<\n");
+ for (fe = doc->fonts->head; fe; fe = fe->next) {
+ char fname[40];
+ int i;
+ object *font;
+
+ sprintf(fname, "f%d", font_index++);
+ fe->name = dupstr(fname);
+
+ font = new_object(&olist);
+
+ objtext(resources, "/");
+ objtext(resources, fe->name);
+ objtext(resources, " ");
+ objref(resources, font);
+ objtext(resources, "\n");
+
+ objtext(font, "<<\n/Type /Font\n/Subtype /Type1\n/Name /");
+ objtext(font, fe->name);
+ objtext(font, "\n/BaseFont /");
+ objtext(font, fe->font->name);
+ objtext(font, "\n/Encoding <<\n/Type /Encoding\n/Differences [");
+
+ for (i = 0; i < 256; i++) {
+ char buf[20];
+ if (!fe->vector[i])
+ continue;
+ sprintf(buf, "\n%d /", i);
+ objtext(font, buf);
+ objtext(font, fe->vector[i] ? fe->vector[i] : ".notdef");
+ }
+
+ objtext(font, "\n]\n>>\n");
+
+ {
+ object *widths = new_object(&olist);
+ objtext(font, "/FirstChar 0\n/LastChar 255\n/Widths ");
+ objref(font, widths);
+ objtext(font, "\n");
+ objtext(widths, "[\n");
+ for (i = 0; i < 256; i++) {
+ char buf[80];
+ double width;
+ if (fe->indices[i] < 0)
+ width = 0.0;
+ else
+ width = fe->font->widths[fe->indices[i]];
+ sprintf(buf, "%g\n", 1000.0 * width / 4096.0);
+ objtext(widths, buf);
+ }
+ objtext(widths, "]\n");
+ }
+
+ objtext(font, ">>\n");
+ }
+ objtext(resources, ">>\n>>\n");
+
+ /*
+ * Define the page objects for each page, and get each one
+ * ready to have a `Parent' specification added to it.
+ */
+ for (page = doc->pages; page; page = page->next) {
+ object *opage;
+
+ opage = new_object(&olist);
+ page->spare = opage;
+ objtext(opage, "<<\n/Type /Page\n");
+ }
+
+ /*
+ * Recursively build the page tree.
+ */
+ make_pages_node(pages, NULL, doc->pages, NULL, resources);
+
+ /*
+ * Create and render the individual pages.
+ */
+ pageno = 0;
+ for (page = doc->pages; page; page = page->next) {
+ object *opage, *cstr;
+ text_fragment *frag;
+ char buf[256];
+
+ opage = (object *)page->spare;
+ /*
+ * At this point the page dictionary is already
+ * half-written, with /Type and /Parent already present. We
+ * continue from there.
+ */
+
+ /*
+ * The PDF spec says /Resources is required, but also says
+ * that it's inheritable and may be omitted if it's present
+ * in a Pages node. In our case it is: it's present in the
+ * topmost /Pages node because we carefully put it there.
+ * So we don't need a /Resources entry here.
+ */
+ sprintf(buf, "/MediaBox [0 0 %g %g]\n",
+ doc->paper_width / 4096.0, doc->paper_height / 4096.0);
+ objtext(opage, buf);
+
+ /*
+ * Now we're ready to define a content stream containing
+ * the actual text on the page.
+ */
+ cstr = new_object(&olist);
+ objtext(opage, "/Contents ");
+ objref(opage, cstr);
+ objtext(opage, "\n");
+
+ objstream(cstr, "BT\n");
+ for (frag = page->first_text; frag; frag = frag->next) {
+ char *c;
+
+ objstream(cstr, "/");
+ objstream(cstr, frag->fe->name);
+ sprintf(buf, " %d Tf 1 0 0 1 %g %g Tm (", frag->fontsize,
+ frag->x/4096.0, frag->y/4096.0);
+ objstream(cstr, buf);
+
+ for (c = frag->text; *c; c++) {
+ if (*c == '(' || *c == ')' || *c == '\\')
+ objstream(cstr, "\\");
+ buf[0] = *c;
+ buf[1] = '\0';
+ objstream(cstr, buf);
+ }
+
+ objstream(cstr, ") Tj\n");
+ }
+ objstream(cstr, "ET");
+
+ objtext(opage, ">>\n");
+ }
+
+ /*
+ * Assemble the final linear form of every object.
+ */
+ for (o = olist.head; o; o = o->next) {
+ rdstringc rs = {0, 0, NULL};
+ char text[80];
+
+ sprintf(text, "%d 0 obj\n", o->number);
+ rdaddsc(&rs, text);
+
+ if (!o->main.text && o->stream.text) {
+ sprintf(text, "<<\n/Length %d\n>>\n", o->stream.pos);
+ rdaddsc(&o->main, text);
+ }
+
+ assert(o->main.text);
+ rdaddsc(&rs, o->main.text);
+ sfree(o->main.text);
+
+ if (rs.text[rs.pos-1] != '\n')
+ rdaddc(&rs, '\n');
+
+ if (o->stream.text) {
+ /*
+ * FIXME: If we ever start compressing stream data then
+ * it will have zero bytes in it, so we'll have to be
+ * more careful than this.
+ */
+ rdaddsc(&rs, "stream\n");
+ rdaddsc(&rs, o->stream.text);
+ rdaddsc(&rs, "\nendstream\n");
+ sfree(o->stream.text);
+ }
+
+ rdaddsc(&rs, "endobj\n");
+
+ o->final = rs.text;
+ o->size = rs.pos;
+ }
+
+ /*
+ * Write out the PDF file.
+ */
+
+ fp = fopen(filename, "wb");
+ if (!fp) {
+ error(err_cantopenw, filename);
+ return;
+ }
+
+ /*
+ * Header
+ */
+ fileoff = fprintf(fp, "%%PDF-1.3\n");
+
+ /*
+ * Body
+ */
+ for (o = olist.head; o; o = o->next) {
+ o->fileoff = fileoff;
+ fwrite(o->final, 1, o->size, fp);
+ fileoff += o->size;
+ }
+
+ /*
+ * Cross-reference table
+ */
+ fprintf(fp, "xref\n");
+ assert(olist.head->number == 1);
+ fprintf(fp, "0 %d\n", olist.tail->number + 1);
+ fprintf(fp, "0000000000 65535 f \n");
+ for (o = olist.head; o; o = o->next) {
+ char entry[40];
+ sprintf(entry, "%010d 00000 n \n", o->fileoff);
+ assert(strlen(entry) == 20);
+ fputs(entry, fp);
+ }
+
+ /*
+ * Trailer
+ */
+ fprintf(fp, "trailer\n<<\n/Size %d\n/Root %d 0 R\n>>\n",
+ olist.tail->number + 1, cat->number);
+ fprintf(fp, "startxref\n%d\n%%%%EOF\n", fileoff);
+
+ fclose(fp);
+
+ sfree(filename);
+}
+
+static object *new_object(objlist *list)
+{
+ object *obj = mknew(object);
+
+ obj->list = list;
+
+ obj->main.text = NULL;
+ obj->main.pos = obj->main.size = 0;
+ obj->stream.text = NULL;
+ obj->stream.pos = obj->stream.size = 0;
+
+ obj->number = list->number++;
+
+ obj->next = NULL;
+ if (list->tail)
+ list->tail->next = obj;
+ else
+ list->head = obj;
+ list->tail = obj;
+
+ obj->size = 0;
+ obj->final = NULL;
+
+ return obj;
+}
+
+static void objtext(object *o, char const *text)
+{
+ rdaddsc(&o->main, text);
+}
+
+static void objstream(object *o, char const *text)
+{
+ rdaddsc(&o->stream, text);
+}
+
+static void objref(object *o, object *dest)
+{
+ char buf[40];
+ sprintf(buf, "%d 0 R", dest->number);
+ rdaddsc(&o->main, buf);
+}
+
+static void make_pages_node(object *node, object *parent, page_data *first,
+ page_data *last, object *resources)
+{
+ int count;
+ page_data *page;
+ char buf[80];
+
+ objtext(node, "<<\n/Type /Pages\n");
+ if (parent) {
+ objtext(node, "/Parent ");
+ objref(node, parent);
+ objtext(node, "\n");
+ }
+
+ /*
+ * Count the pages in this stretch, to see if there are few
+ * enough to reference directly.
+ */
+ count = 0;
+ for (page = first; page; page = page->next) {
+ count++;
+ if (page == last)
+ break;
+ }
+
+ sprintf(buf, "/Count %d\n/Kids [\n", count);
+ objtext(node, buf);
+
+ if (count > TREE_BRANCH) {
+ int i;
+ page_data *thisfirst, *thislast;
+
+ page = first;
+
+ for (i = 0; i < TREE_BRANCH; i++) {
+ int number = (i+1) * count / TREE_BRANCH - i * count / TREE_BRANCH;
+ thisfirst = page;
+ while (number--) {
+ thislast = page;
+ page = page->next;
+ }
+
+ if (thisfirst == thislast) {
+ objref(node, (object *)thisfirst->spare);
+ objtext((object *)thisfirst->spare, "/Parent ");
+ objref((object *)thisfirst->spare, node);
+ objtext((object *)thisfirst->spare, "\n");
+ } else {
+ object *newnode = new_object(node->list);
+ make_pages_node(newnode, node, thisfirst, thislast, NULL);
+ objref(node, newnode);
+ }
+ objtext(node, "\n");
+ }
+
+ assert(thislast == last || page == NULL);
+
+ } else {
+ for (page = first; page; page = page->next) {
+ objref(node, (object *)page->spare);
+ objtext(node, "\n");
+ objtext((object *)page->spare, "/Parent ");
+ objref((object *)page->spare, node);
+ objtext((object *)page->spare, "\n");
+ if (page == last)
+ break;
+ }
+ }
+
+ objtext(node, "]\n");
+
+ if (resources) {
+ objtext(node, "/Resources ");
+ objref(node, resources);
+ objtext(node, "\n");
+ }
+
+ objtext(node, ">>\n");
+}
generated by cgit v1.1 at 2026-04-26 15:48:06 +0000