Beginnings of limited textscreen UTF-8 support.

Subversion-branch: /trunk/chocolate-doom
Subversion-revision: 2487

textscreen/txt_gui.c

@@ -28,6 +28,51 @@
 
 typedef struct txt_cliparea_s txt_cliparea_t;
 
+// Mapping table that converts from the Extended ASCII codes in the
+// CP437 codepage to Unicode character numbers.
+
+static const uint16_t cp437_unicode[] = {
+    0x00c7, 0x00fc, 0x00e9, 0x00e2,         // 80-8f
+    0x00e4, 0x00e0, 0x00e5, 0x00e6,
+    0x00ea, 0x00eb, 0x00e8, 0x00ef,
+    0x00ee, 0x00ec, 0x00c4, 0x00c5,
+
+    0x00c9, 0x00e6, 0x00c6, 0x00f4,         // 90-9f
+    0x00f6, 0x00f2, 0x00fb, 0x00f9,
+    0x00ff, 0x00d6, 0x00dc, 0x00a2,
+    0x00a3, 0x00a5, 0x20a7, 0x0192,
+
+    0x00e1, 0x00ed, 0x00f3, 0x00fa,         // a0-af
+    0x00f1, 0x00d1, 0x00aa, 0x00ba,
+    0x00bf, 0x2310, 0x00ac, 0x00bd,
+    0x00bc, 0x00a1, 0x00ab, 0x00bb,
+
+    0x2591, 0x2592, 0x2593, 0x2502,         // b0-bf
+    0x2524, 0x2561, 0x2562, 0x2556,
+    0x2555, 0x2563, 0x2551, 0x2557,
+    0x255D, 0x255C, 0x255B, 0x2510,
+
+    0x2514, 0x2534, 0x252C, 0x251C,         // c0-cf
+    0x2500, 0x253C, 0x255E, 0x255F,
+    0x255A, 0x2554, 0x2569, 0x2566,
+    0x2560, 0x2550, 0x256C, 0x2567,
+
+    0x2568, 0x2564, 0x2565, 0x2559,         // d0-df
+    0x2558, 0x2552, 0x2553, 0x256B,
+    0x256A, 0x2518, 0x250C, 0x2588,
+    0x2584, 0x258C, 0x2590, 0x2580,
+
+    0x03B1, 0x00DF, 0x0393, 0x03C0,         // e0-ef
+    0x03A3, 0x03C3, 0x00B5, 0x03C4,
+    0x03A6, 0x0398, 0x03A9, 0x03B4,
+    0x221E, 0x03C6, 0x03B5, 0x2229,
+
+    0x2261, 0x00B1, 0x2265, 0x2264,         // f0-ff
+    0x2320, 0x2321, 0x00F7, 0x2248,
+    0x00B0, 0x2219, 0x00B7, 0x221A,
+    0x207F, 0x00B2, 0x25A0, 0x00A0,
+};
+
 struct txt_cliparea_s
 {
     int x1, x2;
@@ -251,6 +296,119 @@ void TXT_DrawString(const char *s)
     TXT_GotoXY(x + strlen(s), y);
 }
 
+// Decode UTF-8 character, incrementing *ptr over the decoded bytes.
+
+static unsigned int DecodeUTF8(const char **ptr)
+{
+    const char *p = *ptr;
+    unsigned int c;
+
+    // UTF-8 decode.
+
+    if ((*p & 0x80) == 0)                     // 1 character (ASCII):
+    {
+        c = *p;
+        *ptr += 1;
+    }
+    else if ((p[0] & 0xe0) == 0xc0            // 2 character:
+          && (p[1] & 0xc0) == 0x80)
+    {
+        c = ((p[0] & 0x1f) << 6)
+          |  (p[1] & 0x3f);
+        *ptr += 2;
+    }
+    else if ((p[0] & 0xf0) == 0xe0            // 3 character:
+          && (p[1] & 0xc0) == 0x80
+          && (p[2] & 0xc0) == 0x80)
+    {
+        c = ((p[0] & 0x0f) << 12)
+          | ((p[1] & 0x3f) << 6)
+          |  (p[2] & 0x3f);
+        *ptr += 3;
+    }
+    else if ((p[0] & 0xf8) == 0xf0            // 4 character:
+          && (p[1] & 0xc0) == 0x80
+          && (p[2] & 0xc0) == 0x80
+          && (p[3] & 0xc0) == 0x80)
+    {
+        c = ((p[0] & 0x07) << 18)
+          | ((p[1] & 0x3f) << 12)
+          | ((p[2] & 0x3f) << 6)
+          |  (p[3] & 0x3f);
+        *ptr += 4;
+    }
+    else
+    {
+        // Decode failure.
+        // Don't bother with 5/6 byte sequences.
+
+        c = 0;
+    }
+
+    return c;
+}
+
+static void PutUnicodeChar(unsigned int c)
+{
+    unsigned int i;
+
+    if (c < 128)
+    {
+        TXT_PutChar(c);
+        return;
+    }
+
+    // We can only display this character if it is in the CP437 codepage.
+
+    for (i = 0; i < 128; ++i)
+    {
+        if (cp437_unicode[i] == c)
+        {
+            TXT_PutChar(128 + i);
+            return;
+        }
+    }
+
+    // Otherwise, print a fallback character (inverted question mark):
+
+    TXT_PutChar('\xa8');
+}
+
+void TXT_DrawUTF8String(const char *s)
+{
+    int x, y;
+    int x1;
+    const char *p;
+    unsigned int c;
+
+    TXT_GetXY(&x, &y);
+
+    if (VALID_Y(y))
+    {
+        x1 = x;
+
+        for (p = s; *p != '\0'; )
+        {
+            c = DecodeUTF8(&p);
+
+            if (c == 0)
+            {
+                break;
+            }
+
+            if (VALID_X(x1))
+            {
+                TXT_GotoXY(x1, y);
+                PutUnicodeChar(c);
+            }
+
+            x1 += 1;
+        }
+    }
+
+    TXT_GotoXY(x + strlen(s), y);
+}
+
 void TXT_DrawHorizScrollbar(int x, int y, int w, int cursor, int range)
 {
     int x1;