Implement strikethrough formatting

.gitignore

@@ -0,0 +1,8 @@
+*.o
+Makefile
+config.cache
+config.h
+config.log
+config.status
+links
+stamp-h

dip.c

@@ -1996,11 +1996,14 @@ bypass_freetype:
  * at least 1 apart
  * Otherwise g_print_text will print nonsense (but won't segfault)
  */
-static void get_underline_pos(int height, int *top, int *bottom)
+static void get_line_pos(int height, int *top, int *bottom, unsigned style)
 {
 	int thickness, baseline;
 	thickness=(height+15)/16;
-	baseline=height/7;
+	if (style == FF_STRIKE)
+		baseline=height/2 - height/12;
+	else
+		baseline=height/7;
 	if (baseline<=0) baseline=1;
 	if (thickness>baseline) thickness=baseline;
 	*top=height-baseline;
@@ -2010,38 +2013,39 @@ static void get_underline_pos(int height, int *top, int *bottom)
 /* *width will be advanced by the width of the text */
 void g_print_text(struct graphics_device *device, int x, int y, struct style *style, unsigned char *text, int *width)
 {
-	int top_underline, bottom_underline, original_width, my_width;
-	unsigned char original_flags;
+	int top_line, bottom_line, original_width, my_width;
+	unsigned char original_flags, line_style;
 	struct rect saved_clip;
 
 	if (y + style->height <= device->clip.y1 || y >= device->clip.y2)
 		goto o;
-	if (style->flags & FF_UNDERLINE) {
-		/* Underline */
+	if (style->flags & FF_UNDERLINE || style->flags & FF_STRIKE) {
+		/* Underline or strike */
 		if (!width) {
 		       width = &my_width;
 		       *width = 0;
 		}
 		original_flags = style->flags;
 		original_width = *width;
-		style->flags &= ~FF_UNDERLINE;
-		get_underline_pos(style->height, &top_underline, &bottom_underline);
-		restrict_clip_area(device, &saved_clip, 0, 0, device->size.x2, y + top_underline);
+		line_style = style->flags & FF_UNDERLINE ? FF_UNDERLINE : FF_STRIKE;
+		style->flags &= ~line_style;
+		get_line_pos(style->height, &top_line, &bottom_line, line_style);
+		restrict_clip_area(device, &saved_clip, 0, 0, device->size.x2, y + top_line);
 		g_print_text(device, x, y, style, text, width);
 		set_clip_area(device, &saved_clip);
-		if (bottom_underline - top_underline == 1) {
+		if (bottom_line - top_line == 1) {
 			/* Line */
-			drv->draw_hline(device, x, y + top_underline, safe_add(x, *width) - original_width, style->underline_color);
+			drv->draw_hline(device, x, y + top_line, safe_add(x, *width) - original_width, style->line_color);
 		} else {
 			/* Area */
-			drv->fill_area(device, x, y + top_underline, safe_add(x, *width) - original_width, y + bottom_underline, style->underline_color);
+			drv->fill_area(device, x, y + top_line, safe_add(x, *width) - original_width, y + bottom_line, style->line_color);
 		}
-		if (bottom_underline < style->height) {
-			/* Do the bottom half only if the underline is above
+		if (bottom_line < style->height) {
+			/* Do the bottom half only if the line is above
 			 * the bottom of the letters.
 			 */
 			*width = original_width;
-			restrict_clip_area(device, &saved_clip, 0, y + bottom_underline, device->size.x2, device->size.y2);
+			restrict_clip_area(device, &saved_clip, 0, y + bottom_line, device->size.x2, device->size.y2);
 			g_print_text(device, x, y, style, text, width);
 			set_clip_area(device, &saved_clip);
 		}
@@ -2275,9 +2279,11 @@ struct style *g_invert_style(struct style *old)
 #ifdef HAVE_FREETYPE
 	st->ft_face = old->ft_face;
 #endif
-	if (st->flags & FF_UNDERLINE) {
-		/* We have to get a foreground color for underlining */
-		st->underline_color = dip_get_color_sRGB((st->r1 << 16) | (st->g1 << 8) | (st->b1));
+	if (st->flags & FF_UNDERLINE || st->flags & FF_STRIKE) {
+		/* We have to get a foreground color for underlining and
+		 * striking
+		 */
+		st->line_color = dip_get_color_sRGB((st->r1 << 16) | (st->g1 << 8) | (st->b1));
 	}
 	st->mono_space = old->mono_space;
 	st->mono_height = old->mono_height;
@@ -2323,9 +2329,11 @@ struct style *g_get_style_font(int fg, int bg, int size, int fflags, unsigned ch
 	else
 		st->ft_face = freetype_get_font(font);
 #endif
-	if (fflags & FF_UNDERLINE) {
-		/* We have to get a foreground color for underlining */
-		st->underline_color = dip_get_color_sRGB(fg);
+	if (fflags & FF_UNDERLINE || fflags & FF_STRIKE) {
+		/* We have to get a foreground color for underlining and
+		 * striking
+		 */
+		st->line_color = dip_get_color_sRGB(fg);
 	}
 	if (fflags & FF_MONOSPACED)
 		load_metric(st, ' ', &st->mono_space, &st->mono_height);

html.c

@@ -967,6 +967,12 @@ static void html_underline(unsigned char *a)
 	format_.attr |= AT_UNDERLINE;
 }
 
+static void html_strike(unsigned char *a)
+{
+	get_js_events(a);
+	format_.attr |= AT_STRIKE;
+}
+
 static void html_fixed(unsigned char *a)
 {
 	get_js_events(a);
@@ -2777,8 +2783,10 @@ static struct element_info elements[] = {
 	{"EM",		html_italic,	0, 0},
 	{"ABBR",	html_italic,	0, 0},
 	{"U",		html_underline,	0, 0},
-	{"S",		html_underline,	0, 0},
-	{"STRIKE",	html_underline,	0, 0},
+	{"INS",		html_underline,	0, 0},
+	{"S",		html_strike,	0, 0},
+	{"DEL",		html_strike,	0, 0},
+	{"STRIKE",	html_strike,	0, 0},
 	{"FIXED",	html_fixed,	0, 0},
 	{"CODE",	html_fixed,	0, 0},
 	{"TT",		html_fixed,	0, 0},

html_gr.c

@@ -113,6 +113,7 @@ static struct style *get_style_by_ta(struct text_attrib *ta)
 
 	fflags = 0;
 	if (ta->attr & AT_UNDERLINE) fflags |= FF_UNDERLINE;
+	if (ta->attr & AT_STRIKE) fflags |= FF_STRIKE;
 	if (ta->attr & AT_BOLD) fflags |= FF_BOLD;
 	if (ta->attr & AT_ITALIC) fflags |= FF_ITALIC;
 	if (ta->attr & AT_FIXED) fflags |= FF_MONOSPACED;

html_r.c

@@ -868,6 +868,7 @@ static void put_chars(void *p_, unsigned char *c, int l)
 		fg = fg_color(fg, bg);
 		if (format_.attr & AT_ITALIC) fg = fg ^ 0x01;
 		if (format_.attr & AT_UNDERLINE) fg = (fg ^ 0x04) | 0x08;
+		if (format_.attr & AT_STRIKE) fg = (fg ^ 0x06);
 		if (format_.attr & AT_BOLD) fg = fg | 0x08;
 		fg = fg_color(fg, bg);
 		if (format_.attr & AT_GRAPHICS) bg = bg | 0x10;

links.h

@@ -2174,9 +2174,11 @@ struct style {
 	/* ?0 are background, ?1 foreground.
 	 * These are unrounded 8-bit sRGB space
 	 */
-	unsigned char flags; /* non-zero means underline */
+	unsigned char flags; /* FF_ flags */
 	int height;
-	long underline_color; /* Valid only if flags are nonzero */
+	long line_color; /* Valid only if flags includes FF_UNDERLINE or
+			  * FF_STRIKE
+			  */
 	int mono_space; /* -1 if the font is not monospaced
 			 * width of the space otherwise
 			 */
@@ -2266,6 +2268,7 @@ int hack_rgb(int rgb);
 #define FF_MONOSPACED	2
 #define FF_ITALIC	4
 #define FF_UNDERLINE	8
+#define FF_STRIKE	16
 
 #ifndef USE_ITALIC
 #define FF_SHAPES	4
@@ -4539,6 +4542,7 @@ void init_grview(void);
 #define AT_FIXED	8
 #define AT_GRAPHICS	16
 #define AT_INVERT	32
+#define AT_STRIKE	64
 
 #define AL_LEFT		0
 #define AL_CENTER	1