atascii.c: better inverse video handling for magazine mode.

1 files changed, 40 insertions, 4 deletions

diff --git a/atascii.c b/atascii.c
index d1d1243..19d7404 100644
--- a/atascii.c
+++ b/atascii.c
@@ -3,6 +3,36 @@
 const char *atascii_inverse_on  = "\x1b[7m";
 const char *atascii_inverse_off = "\x1b[27m";
 
+/* only called in magazine mode. cursor control characters
+   like a bell in the middle of a non-inverse string
+   should not cause it to print {inv}{bell}{norm}. The {bell}
+   is "inherently" inverse (since its high bit is set) but doesn't
+   need to be printed that way. */
+static int affects_inv(int c) {
+	switch(c) {
+		case 0x1b: /* esc */
+		case 0x1c: /* up */
+		case 0x1d: /* down */
+		case 0x1e: /* left */
+		case 0x1f: /* right */
+		case 0x9b: /* EOL */
+		case 0x9c: /* del line */
+		case 0x9d: /* ins line */
+		case 0x9e: /* clear tab */
+		case 0x9f: /* set tab */
+		case 0x7d: /* cls */
+		case 0x7e: /* BS */
+		case 0x7f: /* tab */
+		case 0xfd: /* bell */
+		case 0xfe: /* del chr */
+		case 0xff: /* ins chr */
+			return 0;
+		default:
+			return 1;
+	}
+}
+
+
 int atascii_context_init(atascii_ctx *ctx, int mode, int flags) {
 	memset(ctx, 0, sizeof(atascii_ctx));
 
@@ -64,20 +94,26 @@ char *atascii_a2utf(atascii_ctx *ctx, int src, char *dest) {
 			sequence, and one "inverse off" afterwards. */
 		if(src & 0x80) {
 			if(!ctx->inv) {
-				ctx->inv = 1;
 				if(ctx->mode == ATA_MODE_MAGAZINE) {
-					strcpy(dest, "{inv}");
+					if(affects_inv(src)) {
+						strcpy(dest, "{inv}");
+						ctx->inv = 1;
+					}
 				} else {
 					strcpy(dest, atascii_inverse_on);
+					ctx->inv = 1;
 				}
 			}
 		} else {
 			if(ctx->inv) {
-				ctx->inv = 0;
 				if(ctx->mode == ATA_MODE_MAGAZINE) {
-					strcpy(dest, "{norm}");
+					if(affects_inv(src)) {
+						strcpy(dest, "{norm}");
+						ctx->inv = 0;
+					}
 				} else {
 					strcpy(dest, atascii_inverse_off);
+					ctx->inv = 0;
 				}
 			}
 		}