winansi: code shrink and improvements

Commit b0b7ab792 (winansi: code shrink) noted that combining reverse
vidoe escape sequences (e.g. ESC[7;27m) didn't work properly.

Make further changes to improve the situation:

- revert to keeping the current attributes in a static variable;

- when reverse video is enabled switch the intensity as well as the
  colour components;

- move the code from set_console_attr() into its only caller,
  process_escape();

- use 0xffff instead of 0 as a flag to indicate the attributes
  haven't been initialised.

Saves 44 bytes and seems to work better.

1 files changed, 15 insertions, 41 deletions

diff --git a/win32/winansi.c b/win32/winansi.c
index 45737bf2d..971702f18 100644
--- a/win32/winansi.c
+++ b/win32/winansi.c
@@ -25,7 +25,8 @@
 #define FOREGROUND_ALL (FOREGROUND_RED | FOREGROUND_GREEN | FOREGROUND_BLUE)
 #define BACKGROUND_ALL (BACKGROUND_RED | BACKGROUND_GREEN | BACKGROUND_BLUE)
 
-static WORD plain_attr = 0;
+static WORD plain_attr = 0xffff;
+static WORD current_attr;
 
 static HANDLE get_console(void)
 {
@@ -44,8 +45,8 @@ static WORD get_console_attr(void)
 
 static int is_console(int fd)
 {
-        if (!plain_attr)
-                plain_attr = get_console_attr();
+        if (plain_attr == 0xffff)
+                current_attr = plain_attr = get_console_attr();
         return isatty(fd) && get_console() != INVALID_HANDLE_VALUE;
 }
 
@@ -162,33 +163,6 @@ static void use_alt_buffer(int flag)
         _open_osfhandle((intptr_t)console, O_RDWR|O_BINARY);
 }
 
-static void set_console_attr(WORD attributes, int invert)
-{
-        HANDLE console = get_console();
-        if (invert) {
-                WORD save = attributes;
-                attributes &= ~FOREGROUND_ALL;
-                attributes &= ~BACKGROUND_ALL;
-
-                /* This could probably use a bitmask
-                   instead of a series of ifs */
-                if (save & FOREGROUND_RED)
-                        attributes |= BACKGROUND_RED;
-                if (save & FOREGROUND_GREEN)
-                        attributes |= BACKGROUND_GREEN;
-                if (save & FOREGROUND_BLUE)
-                        attributes |= BACKGROUND_BLUE;
-
-                if (save & BACKGROUND_RED)
-                        attributes |= FOREGROUND_RED;
-                if (save & BACKGROUND_GREEN)
-                        attributes |= FOREGROUND_GREEN;
-                if (save & BACKGROUND_BLUE)
-                        attributes |= FOREGROUND_BLUE;
-        }
-        SetConsoleTextAttribute(console, attributes);
-}
-
 static void clear_buffer(DWORD len, COORD pos)
 {
         HANDLE console = get_console();
@@ -481,9 +455,8 @@ static char *process_escape(char *pos)
         char *str, *func;
         char *bel;
         size_t len;
-        WORD t, attr = get_console_attr();
-        int invert = FALSE;
-        static int inverse = 0;
+        WORD t, attr = current_attr;
+        static int reverse = 0;
 
         switch (pos[1]) {
         case '[':
@@ -513,7 +486,7 @@ static char *process_escape(char *pos)
                         switch (val) {
                         case 0: /* reset */
                                 attr = plain_attr;
-                                inverse = 0;
+                                reverse = 0;
                                 break;
                         case 1: /* bold */
                                 attr |= FOREGROUND_INTENSITY;
@@ -543,13 +516,11 @@ static char *process_escape(char *pos)
                         case 25: /* no blink */
                                 attr &= ~BACKGROUND_INTENSITY;
                                 break;
-                        case 7:  /* inverse on */
-                                invert = !inverse;
-                                inverse = 1;
+                        case 7:  /* reverse video on */
+                                reverse = 1;
                                 break;
-                        case 27: /* inverse off */
-                                invert = inverse;
-                                inverse = 0;
+                        case 27: /* reverse video off */
+                                reverse = 0;
                                 break;
                         case 8:  /* conceal */
                         case 9:  /* strike through */
@@ -612,7 +583,10 @@ static char *process_escape(char *pos)
                         str++;
                 } while (*(str-1) == ';');
 
-                set_console_attr(attr, invert);
+                current_attr = attr;
+                if (reverse)
+                        attr = ((attr >> 4) & 0xf) | ((attr << 4) & 0xf0);
+                SetConsoleTextAttribute(get_console(), attr);
                 break;
         case 'A': /* up */
                 move_cursor_row(-strtol(str, (char **)&str, 10));