Add support for forcing wrapping at the screen boundary

This patch modifies ELinks wrapping behavior slightly.

 * The wrap command now toggles line wrapping in HTML mode, as well as
   text mode.  Note that when the HTML view of a page is wrapped, its
   source view is unwrapped, and vice versa.
 * Tabs in text-mode lines are now handled correctly.
 * Wrapping a line that reaches exactly to the edge of the screen will
   no longer produce a blank line in text mode.
 * Text within extra-wide table cells is now wrapped to less than the
   screen width, to eliminate sideways scrolling.

The last point is only enabled by setting TABLE_LINE_PADDING to a
non-negative number, in the src/setup.h header file, because it is a
significant change of behavior from previous versions.

src/document/html/renderer.c

@@ -643,7 +643,13 @@ del_chars(struct html_context *html_context, int x, int y)
 	move_links(html_context, x, y, -1, -1);
 }
 
-#define overlap(x) int_max((x).width - (x).rightmargin, 0)
+#if TABLE_LINE_PADDING < 0
+# define overlap_width(x) (x).width
+#else
+# define overlap_width(x) int_min((x).width, \
+	html_context->options->box.width - TABLE_LINE_PADDING)
+#endif
+#define overlap(x) int_max(overlap_width(x) - (x).rightmargin, 0)
 
 static int inline
 split_line_at(struct html_context *html_context, int width)
@@ -1380,7 +1386,7 @@ put_chars(struct html_context *html_context, unsigned char *chars, int charslen)
 	part->cx += charslen;
 	renderer_context.nobreak = 0;
 
-	if (!html_is_preformatted()) {
+	if (!(html_context->options->wrap || html_is_preformatted())) {
 		while (part->cx > overlap(par_format)
 		       && part->cx > par_format.leftmargin) {
 			int x = split_line(html_context);

src/document/plain/renderer.c

@@ -447,16 +447,18 @@ add_document_lines(struct plain_renderer *renderer)
 	unsigned char *source = renderer->source;
 	int length = renderer->length;
 	int was_empty_line = 0;
+	int was_wrapped = 0;
 
 	for (; length > 0; renderer->lineno++) {
 		unsigned char *xsource;
 		int width, added, only_spaces = 1, spaces = 0, was_spaces = 0;
 		int last_space = 0;
+		int tab_spaces = 0;
 		int step = 0;
 		int doc_width = int_min(renderer->max_width, length);
 
 		/* End of line detection: We handle \r, \r\n and \n types. */
-		for (width = 0; width < doc_width; width++) {
+		for (width = 0; width + tab_spaces < doc_width; width++) {
 			if (source[width] == ASCII_CR)
 				step++;
 			if (source[width + step] == ASCII_LF)
@@ -469,6 +471,8 @@ add_document_lines(struct plain_renderer *renderer)
 					spaces++;
 				else
 					was_spaces++;
+				if (source[width] == '\t')
+					tab_spaces += 7 - ((width + tab_spaces) % 8);
 			} else {
 				only_spaces = 0;
 				was_spaces = 0;
@@ -476,7 +480,7 @@ add_document_lines(struct plain_renderer *renderer)
 		}
 
 		if (only_spaces && step) {
-			if (renderer->compress && was_empty_line) {
+			if (was_wrapped || (renderer->compress && was_empty_line)) {
 				/* Successive empty lines will appear as one. */
 				length -= step + spaces;
 				source += step + spaces;
@@ -493,6 +497,7 @@ add_document_lines(struct plain_renderer *renderer)
 
 		} else {
 			was_empty_line = 0;
+			was_wrapped = !step;
 
 			if (was_spaces && step) {
 				/* Drop trailing whitespaces. */

src/setup.h

@@ -106,4 +106,8 @@
 #define DEFAULT_TERMINAL_WIDTH		80
 #define DEFAULT_TERMINAL_HEIGHT		25
 
+/* If this is non-negative, lines in extra-wide table cells will be wrapped
+ * to fit in the screen, with this much extra space.  Try 4. */
+#define TABLE_LINE_PADDING		-1
+
 #endif