Fixed biggest performance bottleneck on draw_user_interface: print white spaces.

2 files changed, 25 insertions, 17 deletions

diff --git a/modules/TUI/module.jai b/modules/TUI/module.jai
index 7c3a71d..a5db3bf 100644
--- a/modules/TUI/module.jai
+++ b/modules/TUI/module.jai
@@ -572,7 +572,7 @@ read_input_line :: (count_limit: int, is_visible: bool = true) -> string, Key {
                 idx += 1;
 
                 // Truncate string to avoid incomplete utf8 codes on the string tail.
-                truncate(*str, count_limit);
+                str.count = truncate(str, count_limit).count;
         }
     }
 
diff --git a/modules/UTF8.jai b/modules/UTF8.jai
index b583809..205e57d 100644
--- a/modules/UTF8.jai
+++ b/modules/UTF8.jai
@@ -21,15 +21,15 @@ count_character_bytes :: inline (leading_byte: u8) -> int {
     return 1;
 }
 
-// Truncates the string to the provided length and zeroes the discarded bytes.
-// Returns the length of truncated string or -1 if string has no data.
-truncate :: (str: *string, length: int) -> length: int {
-    if str.data == null     then return -1;
+// Returns the string (using same str.data) truncated to the provided length.
+truncate :: (str: string, length: int) -> string {
     
-    if str.count < length   then length = str.count;
+    if str.data == null     then return "";
+
+    if str.count < length   then return .{str.count, str.data};
     
-    data := str.data;
-    count := str.count;
+    data    := str.data;
+    count   := str.count;
 
     // Find index of first continuation byte.
     idx := length;
@@ -50,12 +50,10 @@ truncate :: (str: *string, length: int) -> length: int {
         && !(continuation_bytes == 2 && (data[idx - 1] & 0xF0) == 0xE0)
         && !(continuation_bytes == 3 && (data[idx - 1] & 0xF8) == 0xF0)
     ) {
-        length -= (continuation_bytes + 1); // Remove start byte, ence '+ 1'.
+        length -= (continuation_bytes + 1); // Remove start byte, hence '+ 1'.
     }
-
-    memset(data + length, 0, count - length);
-    str.count = length;
-    return length;
+    
+    return .{length, str.data};
 }
 
 // Returns true when the string is empty or consists of space characters.
@@ -78,13 +76,23 @@ is_empty :: (str: string) -> bool {
 }
 
 // Counts the number of characters.
-count_characters :: (str: string) -> int {
+count_characters :: (str: string, $is_null_terminated := false) -> int {
     characters := 0;
     idx := 0;
-    while idx < str.count {
-        idx += count_character_bytes(str[idx]);
-        characters += 1;
+    
+    #if is_null_terminated {
+        while idx < str.count && str[idx] != 0 {
+            idx += count_character_bytes(str[idx]);
+            characters += 1;
+        }
+    }
+    else {
+        while idx < str.count {
+            idx += count_character_bytes(str[idx]);
+            characters += 1;
+        }
     }
+    
     return characters;
 }