[PATCH 08/10] terminal: Implement character set switching

Marty Jack martyj19 at comcast.net
Sat Jan 8 11:18:57 PST 2011


On 01/07/2011 02:47 PM, Callum Lowcay wrote:
> Includes the 3 vt100 character sets.  Some of the graphic symbols don't
> display because they are not included in the default font.  Apparantly
> the cairo toy font API doesn't do font substitution.
> 
> Signed-off-by: Callum Lowcay <callum at callumscode.com>
> ---
>  clients/terminal.c |  117 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 117 insertions(+), 0 deletions(-)
> 
> diff --git a/clients/terminal.c b/clients/terminal.c
> index 88864c3..a56f29b 100644
> --- a/clients/terminal.c
> +++ b/clients/terminal.c
> @@ -166,6 +166,69 @@ utf8_next_char(struct utf8_state_machine *machine, char c)
>  	return machine->state;
>  }
>  
> +struct char_sub {
> +	union utf8_char match;
> +	union utf8_char replace;
> +};
> +/* Set last char_sub match to NULL char */
> +typedef struct char_sub *character_set;
> +
> +struct char_sub CS_US[] = {
> +	{{{0, }}, {{0, }}}
> +};
> +static struct char_sub CS_UK[] = {
> +	{{{'#', 0, }}, {{0xC2, 0xA3, 0, }}},
> +	{{{0, }}, {{0, }}}
> +};
> +static struct char_sub CS_SPECIAL[] = {
> +	{{{'`', 0, }}, {{0xE2, 0x99, 0xA6, 0}}}, /* diamond */
> +	{{{'a', 0, }}, {{0xE2, 0x96, 0x92, 0}}}, /* 50% cell */
> +	{{{'b', 0, }}, {{0xE2, 0x90, 0x89, 0}}}, /* HT */
> +	{{{'c', 0, }}, {{0xE2, 0x90, 0x8C, 0}}}, /* FF */
> +	{{{'d', 0, }}, {{0xE2, 0x90, 0x8D, 0}}}, /* CR */
> +	{{{'e', 0, }}, {{0xE2, 0x90, 0x8A, 0}}}, /* LF */
> +	{{{'f', 0, }}, {{0xC2, 0xB0, 0, }}}, /* Degree */
> +	{{{'g', 0, }}, {{0xC2, 0xB1, 0, }}}, /* Plus/Minus */
> +	{{{'h', 0, }}, {{0xE2, 0x90, 0xA4, 0}}}, /* NL */
> +	{{{'i', 0, }}, {{0xE2, 0x90, 0x8B, 0}}}, /* VT */
> +	{{{'j', 0, }}, {{0xE2, 0x94, 0x98, 0}}}, /* CN_RB */
> +	{{{'k', 0, }}, {{0xE2, 0x94, 0x90, 0}}}, /* CN_RT */
> +	{{{'l', 0, }}, {{0xE2, 0x94, 0x8C, 0}}}, /* CN_LT */
> +	{{{'m', 0, }}, {{0xE2, 0x94, 0x94, 0}}}, /* CN_RB */
> +	{{{'n', 0, }}, {{0xE2, 0x94, 0xBC, 0}}}, /* CROSS */
> +	{{{'o', 0, }}, {{0xE2, 0x94, 0x80, 0}}}, /* H */
> +	{{{'p', 0, }}, {{0xE2, 0x94, 0x80, 0}}}, /* H */
> +	{{{'q', 0, }}, {{0xE2, 0x94, 0x80, 0}}}, /* H */
> +	{{{'r', 0, }}, {{0xE2, 0x94, 0x80, 0}}}, /* H */
> +	{{{'s', 0, }}, {{0xE2, 0x94, 0x80, 0}}}, /* H */
> +	{{{'t', 0, }}, {{0xE2, 0x94, 0x9C, 0}}}, /* TR */
> +	{{{'u', 0, }}, {{0xE2, 0x94, 0xA4, 0}}}, /* TL */
> +	{{{'v', 0, }}, {{0xE2, 0x94, 0xB4, 0}}}, /* TU */
> +	{{{'w', 0, }}, {{0xE2, 0x94, 0xAC, 0}}}, /* TD */
> +	{{{'x', 0, }}, {{0xE2, 0x94, 0x82, 0}}}, /* V */
> +	{{{'y', 0, }}, {{0xE2, 0x89, 0xA4, 0}}}, /* LE */
> +	{{{'z', 0, }}, {{0xE2, 0x89, 0xA5, 0}}}, /* GE */
> +	{{{'{', 0, }}, {{0xCF, 0x80, 0, }}}, /* PI */
> +	{{{'|', 0, }}, {{0xE2, 0x89, 0xA0, 0}}}, /* NEQ */
> +	{{{'}', 0, }}, {{0xC2, 0xA3, 0, }}}, /* POUND */
> +	{{{'~', 0, }}, {{0xE2, 0x8B, 0x85, 0}}}, /* DOT */
> +	{{{0, }}, {{0, }}}
> +};
> +
> +static void
> +apply_char_set(character_set cs, union utf8_char *utf8)
> +{
> +	int i = 0;
> +	
> +	while (cs[i].match.byte[0]) {
> +		if ((*utf8).ch == cs[i].match.ch) {
> +			*utf8 = cs[i].replace;
> +			break;
> +		}
> +		i++;
> +	}
> +}
> +
>  struct terminal_color { double r, g, b, a; };
>  struct attr {
>  	unsigned char fg, bg;
> @@ -202,6 +265,8 @@ struct terminal {
>  	struct attr saved_attr;
>  	union utf8_char last_char;
>  	int margin_top, margin_bottom;
> +	character_set cs, g0, g1;
> +	character_set saved_cs, saved_g0, saved_g1;
>  	int data_pitch, attr_pitch;  /* The width in bytes of a line */
>  	int width, height, start, row, column;
>  	int saved_row, saved_column;
> @@ -249,6 +314,14 @@ terminal_init(struct terminal *terminal)
>  	terminal->row = 0;
>  	terminal->column = 0;
>  
> +	terminal->g0 = CS_US;
> +	terminal->g1 = CS_US;
> +	terminal->cs = terminal->g0;
> +
> +	terminal->saved_g0 = terminal->g0;
> +	terminal->saved_g1 = terminal->g1;
> +	terminal->saved_cs = terminal->cs;
> +
>  	terminal->saved_attr = terminal->curr_attr;
>  	terminal->saved_origin_mode = terminal->origin_mode;
>  	terminal->saved_row = terminal->row;
> @@ -714,6 +787,12 @@ handle_term_parameter(struct terminal *terminal, int code, int sr)
>  
>  	if (terminal->qmark_flag) {
>  		switch(code) {
> +		case 2:  /* DECANM */
> +			/* No VT52 support yet */
> +			terminal->g0 = CS_US;
> +			terminal->g1 = CS_US;
> +			terminal->cs = terminal->g0;
> +			break;
>  		case 3:  /* DECCOLM */
>  			if (sr)
>  				terminal_resize(terminal, 132, 24);
> @@ -1147,12 +1226,18 @@ handle_non_csi_escape(struct terminal *terminal, char code)
>  		terminal->saved_column = terminal->column;
>  		terminal->saved_attr = terminal->curr_attr;
>  		terminal->saved_origin_mode = terminal->origin_mode;
> +		terminal->saved_cs = terminal->cs;
> +		terminal->saved_g0 = terminal->g0;
> +		terminal->saved_g1 = terminal->g1;
>  		break;
>  	case '8':    /* DECRC */
>  		terminal->row = terminal->saved_row;
>  		terminal->column = terminal->saved_column;
>  		terminal->curr_attr = terminal->saved_attr;
>  		terminal->origin_mode = terminal->saved_origin_mode;
> +		terminal->cs = terminal->saved_cs;
> +		terminal->g0 = terminal->saved_g0;
> +		terminal->g1 = terminal->saved_g1;
>  		break;
>  	default:
>  		fprintf(stderr, "Unknown escape code: %c\n", code);
> @@ -1179,6 +1264,30 @@ handle_special_escape(struct terminal *terminal, char special, char code)
>  			fprintf(stderr, "Unknown HASH escape #%c\n", code);
>  			break;
>  		}
> +	} else if (special == '(' || special == ')') {
> +		switch(code) {
> +		case '0':
> +			if (special == '(')
> +				terminal->g0 = CS_SPECIAL;
> +			else
> +				terminal->g1 = CS_SPECIAL;
> +			break;
> +		case 'A':
> +			if (special == '(')
> +				terminal->g0 = CS_UK;
> +			else
> +				terminal->g1 = CS_UK;
> +			break;
> +		case 'B':
> +			if (special == '(')
> +				terminal->g0 = CS_US;
> +			else
> +				terminal->g1 = CS_US;
> +			break;
> +		default:
> +			fprintf(stderr, "Unknown character set %c\n", code);
> +			break;
> +		}
>  	} else {
>  		fprintf(stderr, "Unknown special escape %c%c\n", special, code);
>  	}
> @@ -1307,6 +1416,12 @@ handle_special_char(struct terminal *terminal, char c)
>  	case '\a':
>  		/* Bell */
>  		break;
> +	case '\x0E': /* SO */
> +		terminal->cs = terminal->g1;
> +		break;
> +	case '\x0F': /* SI */
> +		terminal->cs = terminal->g0;
> +		break;
>  	default:
>  		return 0;
>  	}
> @@ -1321,6 +1436,8 @@ handle_char(struct terminal *terminal, union utf8_char utf8)
>  	struct attr *attr_row;
>  	
>  	if (handle_special_char(terminal, utf8.byte[0])) return;
> +
> +	apply_char_set(terminal->cs, &utf8);
>  	
>  	/* There are a whole lot of non-characters, control codes,
>  	 * and formatting codes that should probably be ignored,

In looking at this I decided the way to go was to draw the line drawing characters by hand as lines and the visible controls by hand positioning them in the character cell with a smaller font.  (It turns out the font coverage for the visible controls is poor.)  The one glyph I didn't find and didn't make a decision on is the checkerboard symbol.

Do not forget to test with combining Unicode characters including cases where you have several combining characters in a row that are supposed to overlay the non-combining character.


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