X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/halibut/blobdiff_plain/6e969fcfe897ed651145d5cadfc6764c2a6bce6d..7c8c4239f226d2dabdd84dabae9f5869d6d64f2f:/bk_pdf.c

diff --git a/bk_pdf.c b/bk_pdf.c
index 42a0018..f6babe5 100644
--- a/bk_pdf.c
+++ b/bk_pdf.c
@@ -2,17 +2,779 @@
  * 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)
 {
-    return NULL;
+    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 pdf_string(void (*add)(object *, char const *),
+		       object *, char const *);
+static void objref(object *o, object *dest);
+
+static void make_pages_node(object *node, object *parent, page_data *first,
+			    page_data *last, object *resources);
+static int make_outline(object *parent, outline_element *start, int n,
+			int open);
+static int pdf_versionid(FILE *fp, word *words);
+
 void pdf_backend(paragraph *sourceform, keywordlist *keywords,
-		 indexdata *idx, void *unused) {
+		 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) {
+	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);
+
+    /*
+     * 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/PageMode /UseOutlines\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;
+	rect *r;
+	text_fragment *frag, *frag_end;
+	char buf[256];
+	int x, y, lx, ly;
+
+	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");
+
+	/*
+	 * Render any rectangles on the page.
+	 */
+	for (r = page->first_rect; r; r = r->next) {
+	    char buf[512];
+	    sprintf(buf, "%g %g %g %g re f\n", r->x / 4096.0,
+		    r->y / 4096.0, r->w / 4096.0, r->h / 4096.0);
+	    objstream(cstr, buf);
+	}
+
+	objstream(cstr, "BT\n");
+
+	/*
+	 * PDF tracks two separate current positions: the position
+	 * given in the `line matrix' and the position given in the
+	 * `text matrix'. We must therefore track both as well.
+	 * They start off at -1 (unset).
+	 */
+	lx = ly = -1;
+	x = y = -1;
+
+	frag = page->first_text;
+	while (frag) {
+	    /*
+	     * For compactness, I'm going to group text fragments
+	     * into subsequences that use the same font+size. So
+	     * first find the end of this subsequence.
+	     */
+	    for (frag_end = frag;
+		 (frag_end &&
+		  frag_end->fe == frag->fe &&
+		  frag_end->fontsize == frag->fontsize);
+		 frag_end = frag_end->next);
+
+	    /*
+	     * Now select the text fragment, and prepare to display
+	     * the text.
+	     */
+	    objstream(cstr, "/");
+	    objstream(cstr, frag->fe->name);
+	    sprintf(buf, " %d Tf ", frag->fontsize);
+	    objstream(cstr, buf);
+
+	    while (frag && frag != frag_end) {
+		/*
+		 * Place the text position for the first piece of
+		 * text.
+		 */
+		if (lx < 0) {
+		    sprintf(buf, "1 0 0 1 %g %g Tm ",
+			    frag->x/4096.0, frag->y/4096.0);
+		} else {
+		    sprintf(buf, "%g %g Td ",
+			    (frag->x - lx)/4096.0, (frag->y - ly)/4096.0);
+		}
+		objstream(cstr, buf);
+		lx = x = frag->x;
+		ly = y = frag->y;
+
+		/*
+		 * See if we're going to use Tj (show a single
+		 * string) or TJ (show an array of strings with
+		 * x-spacings between them). We determine this by
+		 * seeing if there's more than one text fragment in
+		 * sequence with the same y-coordinate.
+		 */
+		if (frag->next && frag->next != frag_end &&
+		    frag->next->y == y) {
+		    /*
+		     * The TJ strategy.
+		     */
+		    objstream(cstr, "[");
+		    while (frag && frag != frag_end && frag->y == y) {
+			if (frag->x != x) {
+			    sprintf(buf, "%g",
+				    (x - frag->x) * 1000.0 /
+				    (4096.0 * frag->fontsize));
+			    objstream(cstr, buf);
+			}
+			pdf_string(objstream, cstr, frag->text);
+			x = frag->x + frag->width;
+			frag = frag->next;
+		    }
+		    objstream(cstr, "]TJ\n");
+		} else
+		{
+		    /*
+		     * The Tj strategy.
+		     */
+		    pdf_string(objstream, cstr, frag->text);
+		    objstream(cstr, "Tj\n");
+		    frag = frag->next;
+		}
+	    }
+	}
+	objstream(cstr, "ET");
+
+	/*
+	 * Also, we want an annotation dictionary containing the
+	 * cross-references from this page.
+	 */
+	if (page->first_xref) {
+	    xref *xr;
+	    objtext(opage, "/Annots [\n");
+
+	    for (xr = page->first_xref; xr; xr = xr->next) {
+		object *annot;
+		char buf[256];
+
+		annot = new_object(&olist);
+		objref(opage, annot);
+		objtext(opage, "\n");
+
+		objtext(annot, "<<\n/Type /Annot\n/Subtype /Link\n/Rect [");
+		sprintf(buf, "%g %g %g %g",
+			xr->lx / 4096.0, xr->by / 4096.0,
+			xr->rx / 4096.0, xr->ty / 4096.0);
+		objtext(annot, buf);
+		objtext(annot, "]\n/Border [0 0 0]\n");
+
+		if (xr->dest.type == PAGE) {
+		    objtext(annot, "/Dest [");
+		    objref(annot, (object *)xr->dest.page->spare);
+		    objtext(annot, " /XYZ null null null]\n");
+		} else {
+		    objtext(annot, "/A <<\n/Type /Action\n/S /URI\n/URI ");
+		    pdf_string(objtext, annot, xr->dest.url);
+		    objtext(annot, "\n>>\n");
+		}
+
+		objtext(annot, ">>\n");
+	    }
+
+	    objtext(opage, "]\n");
+	}
+
+	objtext(opage, ">>\n");
+    }
+
+    /*
+     * Set up the outlines dictionary.
+     */
+    {
+	int topcount;
+	char buf[80];
+
+	objtext(outlines, "<<\n/Type /Outlines\n");
+	topcount = make_outline(outlines, doc->outline_elements,
+				doc->n_outline_elements, TRUE);
+	sprintf(buf, "/Count %d\n>>\n", topcount);
+	objtext(outlines, buf);
+    }
+
+    /*
+     * 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. I'm going to put the version IDs in the header as
+     * well, simply in PDF comments.
+     */
+    fileoff = fprintf(fp, "%%PDF-1.3\n");
+    for (p = sourceform; p; p = p->next)
+	if (p->type == para_VersionID)
+	    fileoff += pdf_versionid(fp, p->words);
+
+    /*
+     * 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);
+    }
+
     /*
-     * FIXME
+     * Trailer
      */
-    printf("[pdf] %p = %s\n", unused, unused);
+    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");
+}
+
+/*
+ * In text on the page, PDF uses the PostScript font model, which
+ * means that glyphs are identified by PS strings and hence font
+ * encoding can be managed independently of the supplied encoding
+ * of the font. However, in the document outline, the PDF spec
+ * simply asks for ordinary text strings without mentioning what
+ * character set they are supposed to be interpreted in.
+ * 
+ * Therefore, for the moment, I'm going to assume they're US-ASCII
+ * only. If anyone knows better, they should let me know :-/
+ */
+static int pdf_convert(wchar_t *s, char **result) {
+    int doing = (result != 0);
+    int ok = TRUE;
+    char *p = NULL;
+    int plen = 0, psize = 0;
+
+    for (; *s; s++) {
+	wchar_t c = *s;
+	char outc;
+
+	if (c >= 32 && c <= 126) {
+	    /* Char is OK. */
+	    outc = (char)c;
+	} else {
+	    /* Char is not OK. */
+	    ok = FALSE;
+	    outc = 0xBF;	       /* approximate the good old DEC `uh?' */
+	}
+	if (doing) {
+	    if (plen >= psize) {
+		psize = plen + 256;
+		p = resize(p, psize);
+	    }
+	    p[plen++] = outc;
+	}
+    }
+    if (doing) {
+	p = resize(p, plen+1);
+	p[plen] = '\0';
+	*result = p;
+    }
+    return ok;
+}
+
+static int make_outline(object *parent, outline_element *items, int n,
+			int open)
+{
+    int level, totalcount = 0;
+    outline_element *itemp;
+    object *curr, *prev = NULL, *first = NULL, *last = NULL;
+
+    assert(n > 0);
+
+    level = items->level;
+
+    while (n > 0) {
+	char *title;
+
+	/*
+	 * Here we expect to be sitting on an item at the given
+	 * level. So we start by constructing an outline entry for
+	 * that item.
+	 */
+	assert(items->level == level);
+
+	pdf_convert(items->pdata->outline_title, &title);
+
+	totalcount++;
+	curr = new_object(parent->list);
+	if (!first) first = curr;
+	last = curr;
+	objtext(curr, "<<\n/Title ");
+	pdf_string(objtext, curr, title);
+	objtext(curr, "\n/Parent ");
+	objref(curr, parent);
+	objtext(curr, "\n/Dest [");
+	objref(curr, (object *)items->pdata->first->page->spare);
+	objtext(curr, " /XYZ null null null]\n");
+	if (prev) {
+	    objtext(curr, "/Prev ");
+	    objref(curr, prev);
+	    objtext(curr, "\n");
+
+	    objtext(prev, "/Next ");
+	    objref(prev, curr);
+	    objtext(prev, "\n>>\n");
+	}
+	prev = curr;
+
+	items++, n--;
+	for (itemp = items; itemp < items+n && itemp->level > level;
+	     itemp++);
+
+	if (itemp > items) {
+	    char buf[80];
+	    int count = make_outline(curr, items, itemp - items, FALSE);
+	    if (!open)
+		count = -count;
+	    else
+		totalcount += count;
+	    sprintf(buf, "/Count %d\n", count);
+	    objtext(curr, buf);
+	}
+
+	n -= itemp - items;
+	items = itemp;
+    }
+    objtext(prev, ">>\n");
+
+    assert(first && last);
+    objtext(parent, "/First ");
+    objref(parent, first);
+    objtext(parent, "\n/Last ");
+    objref(parent, last);
+    objtext(parent, "\n");
+
+    return totalcount;
+}
+
+static int pdf_versionid(FILE *fp, word *words)
+{
+    int ret;
+
+    ret = fprintf(fp, "%% ");
+
+    for (; words; words = words->next) {
+	char *text;
+	int type;
+
+	switch (words->type) {
+	  case word_HyperLink:
+	  case word_HyperEnd:
+	  case word_UpperXref:
+	  case word_LowerXref:
+	  case word_XrefEnd:
+	  case word_IndexRef:
+	    continue;
+	}
+
+	type = removeattr(words->type);
+
+	switch (type) {
+	  case word_Normal:
+	    text = utoa_dup(words->text);
+	    break;
+	  case word_WhiteSpace:
+	    text = dupstr(" ");
+	    break;
+	  case word_Quote:
+	    text = dupstr("'");
+	    break;
+	}
+
+	fputs(text, fp);
+	ret += strlen(text);
+	sfree(text);
+    }
+
+    ret += fprintf(fp, "\n");
+
+    return ret;
+}
+
+static void pdf_string(void (*add)(object *, char const *),
+		       object *o, char const *str)
+{
+    char const *p;
+
+    add(o, "(");
+    for (p = str; *p; p++) {
+	char c[2];
+	if (*p == '\\' || *p == '(' || *p == ')')
+	    add(o, "\\");
+	c[0] = *p;
+	c[1] = '\0';
+	add(o, c);
+    }
+    add(o, ")");
 }