Compacted PS and PDF output files by removing redundant reiterations

of the same font and position designations. Reduced the size of the
Halibut manual PDF to less than half what it started out as, and the
PS one to more like a third of its original size.

[originally from svn r4083]

1 files changed, 104 insertions, 35 deletions

diff --git a/bk_pdf.c b/bk_pdf.c
index fe10894..f6babe5 100644
--- a/bk_pdf.c
+++ b/bk_pdf.c
@@ -56,6 +56,8 @@ struct objlist_Tag {
 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,
@@ -195,8 +197,9 @@ void pdf_backend(paragraph *sourceform, keywordlist *keywords,
     for (page = doc->pages; page; page = page->next) {
 	object *opage, *cstr;
 	rect *r;
-	text_fragment *frag;
+	text_fragment *frag, *frag_end;
 	char buf[256];
+	int x, y, lx, ly;
 
 	opage = (object *)page->spare;
 	/*
@@ -236,24 +239,89 @@ void pdf_backend(paragraph *sourceform, keywordlist *keywords,
 	}
 
 	objstream(cstr, "BT\n");
-	for (frag = page->first_text; frag; frag = frag->next) {
-	    char *c;
 
+	/*
+	 * 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 1 0 0 1 %g %g Tm (", frag->fontsize,
-		    frag->x/4096.0, frag->y/4096.0);
+	    sprintf(buf, " %d Tf ", frag->fontsize);
 	    objstream(cstr, buf);
 
-	    for (c = frag->text; *c; c++) {
-		if (*c == '(' || *c == ')' || *c == '\\')
-		    objstream(cstr, "\\");
-		buf[0] = *c;
-		buf[1] = '\0';
+	    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, ") Tj\n");
 	}
 	objstream(cstr, "ET");
 
@@ -285,18 +353,9 @@ void pdf_backend(paragraph *sourceform, keywordlist *keywords,
 		    objref(annot, (object *)xr->dest.page->spare);
 		    objtext(annot, " /XYZ null null null]\n");
 		} else {
-		    char *p;
-
-		    objtext(annot, "/A <<\n/Type /Action\n/S /URI\n/URI (");
-		    for (p = xr->dest.url; *p; p++) {
-			char c[2];
-			c[0] = *p;
-			c[1] = '\0';
-			if (*p == '(' || *p == ')' || *p == '\\')
-			    objtext(annot, "\\");
-			objtext(annot, c);
-		    }
-		    objtext(annot, ")\n>>\n");
+		    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");
@@ -596,7 +655,7 @@ static int make_outline(object *parent, outline_element *items, int n,
     level = items->level;
 
     while (n > 0) {
-	char *title, *p;
+	char *title;
 
 	/*
 	 * Here we expect to be sitting on an item at the given
@@ -611,16 +670,9 @@ static int make_outline(object *parent, outline_element *items, int n,
 	curr = new_object(parent->list);
 	if (!first) first = curr;
 	last = curr;
-	objtext(curr, "<<\n/Title (");
-	for (p = title; *p; p++) {
-	    char c[2];
-	    if (*p == '\\' || *p == '(' || *p == ')')
-		objtext(curr, "\\");
-	    c[0] = *p;
-	    c[1] = '\0';
-	    objtext(curr, c);
-	}
-	objtext(curr, ")\n/Parent ");
+	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);
@@ -709,3 +761,20 @@ static int pdf_versionid(FILE *fp, word *words)
 
     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, ")");
+}