From def9c7e70df26779af4a59e0e82e9411b15f8199 Mon Sep 17 00:00:00 2001
From: Mitya Selivanov <automainint@guattari.tech>
Date: Sat, 10 Aug 2024 18:41:57 +0200
Subject: Text kerning

---
 examples/ui.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 58 insertions(+), 16 deletions(-)

(limited to 'examples/ui.c')

diff --git a/examples/ui.c b/examples/ui.c
index 157095a..afb9dbf 100755
--- a/examples/ui.c
+++ b/examples/ui.c
@@ -188,9 +188,10 @@ b8 char_bit(c8 c, i64 column_index, i64 row_index) {
 
   i64 bit_index   = (c - 32) * CHAR_NUM_BITS + row_index * CHAR_NUM_BITS_X + column_index;
   i64 qword_index = bit_index / 64;
+  if (qword_index < 0 || qword_index >= BITFONT_LEN)
+    return 0;
   u64 mask        = 1ull << (bit_index % 64);
-
-  return qword_index < 0 || qword_index >= BITFONT_LEN ? 0 : !!(bitfont[qword_index] & mask);
+  return !!(bitfont[qword_index] & mask);
 }
 
 u64 char_column_convolved(c8 c, i64 column_index) {
@@ -200,13 +201,11 @@ u64 char_column_convolved(c8 c, i64 column_index) {
   u64 column = 0;
 
   for (i64 y = 0; y < CHAR_NUM_BITS_Y; ++y) {
-    i64 bit_index = (c - 32) * CHAR_NUM_BITS + y * CHAR_NUM_BITS_X + column_index;
-    u64 mask      = 1ull << (bit_index % 64);
-
     if (!char_bit(c, column_index, y))
       continue;
 
-    column |= mask;
+    u64 mask  = 1ull << y;
+    column   |= mask;
 
     //  colvolution
     if (mask != 1)          column |= mask >> 1;
@@ -242,18 +241,61 @@ i64 char_width(c8 c) {
   return width;
 }
 
-i64 text_width(i64 num_chars, c8 *text) {
+i64 char_spacing(i64 num_chars, c8 *text, i64 index) {
   assert(text != NULL);
 
-  i64 width = 0;
+  if (index < 0 || index + 1 >= num_chars)
+    return 0;
+
+  u64 a = char_column_convolved(text[index], char_width(text[index]) - 1);
+  u64 b = char_column_convolved(text[index + 1], 0);
+
+  if (!!(a & b))
+    return 1;
+
+  return 0;
+}
+
+i64 enum_text_columns(i64 num_chars, c8 *text) {
+  assert(text != NULL);
+
+  i64 cols = 0;
+  i64 n    = 0;
 
   for (i64 i = 0; i < num_chars; ++i) {
-    if (i > 0)
-      ++width;
-    width += char_width(text[i]);
+    if (text[i] <= ' ') {
+      if (text[i] == '\n')
+        n = 0;
+      else if (text[i] == '\b' && i > 0)
+        n -= char_width(text[i - 1]) + char_spacing(num_chars, text, i - 1);
+      else if (text[i] == '\r')
+        n = 0;
+      else
+        n += char_width(' ') + char_spacing(num_chars, text, i);
+      continue;
+    }
+    n += char_width(text[i]) + char_spacing(num_chars, text, i);
   }
 
-  return width;
+  if (cols < n)
+    cols = n;
+
+  return cols;
+}
+
+i64 enum_text_rows(i64 num_chars, c8 *text) {
+  assert(text != NULL);
+
+  i64 rows = 0;
+
+  for (i64 i = 0; i < num_chars; ++i)
+    if (text[i] == '\n')
+      ++rows;
+
+  if (num_chars > 0 && text[num_chars - 1] != '\n')
+    ++rows;
+
+  return rows;
 }
 
 void print_text(u32 color, i64 x0, i64 y0, f64 scale_x, f64 scale_y, i64 num_chars, c8 *text) {
@@ -272,11 +314,11 @@ void print_text(u32 color, i64 x0, i64 y0, f64 scale_x, f64 scale_y, i64 num_cha
         y += scale_y;
       }
       else if (text[n] == '\b' && n > 0)
-        x -= kx * (char_width(text[n - 1]) + 1);
+        x -= kx * (char_width(text[n - 1]) + char_spacing(num_chars, text, n - 1));
       else if (text[n] == '\r')
         x  = x0;
       else
-        x += kx * (char_width(' ') + 1);
+        x += kx * (char_width(' ') + char_spacing(num_chars, text, n));
       continue;
     }
 
@@ -304,7 +346,7 @@ void print_text(u32 color, i64 x0, i64 y0, f64 scale_x, f64 scale_y, i64 num_cha
       }
     }
 
-    x += kx * (num_cols + 1);
+    x += kx * (num_cols + char_spacing(num_chars, text, n));
   }
 }
 
@@ -329,7 +371,7 @@ i32 main(i32 argc, c8 **argv) {
 
     i64 color = 0xff7f7f;
 
-    if (platform.cursor_x >= 80 && platform.cursor_x < 80 + (text_width(14, "Hello, Sailor!") * 80) / (CHAR_NUM_BITS_X + 1) &&
+    if (platform.cursor_x >= 80 && platform.cursor_x < 80 + (enum_text_columns(14, "Hello, Sailor!") * 80) / (CHAR_NUM_BITS_X + 1) &&
         platform.cursor_y >= 80 && platform.cursor_y < 180)
       color = 0xffffff;
 
-- 
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