(svn r9003) -Codechange: Introduce a function Utf8PrevCharLen that finds the starting character of an UTF-8 sequence from a given position and returns the length to the first UTF-8 encoding byte of that sequence.
--- a/src/misc_gui.cpp Sat Mar 03 22:15:37 2007 +0000
+++ b/src/misc_gui.cpp Sun Mar 04 00:49:40 2007 +0000
@@ -805,11 +805,7 @@
uint width;
size_t len;
- if (backspace) {
- do {
- tb->caretpos--;
- } while (IsUtf8Part(*(tb->buf + tb->caretpos)));
- }
+ if (backspace) tb->caretpos -= Utf8PrevCharLen(tb->buf + tb->caretpos);
len = Utf8Decode(&c, tb->buf + tb->caretpos);
width = GetCharacterWidth(FS_NORMAL, c);
@@ -892,10 +888,7 @@
if (tb->caretpos != 0) {
WChar c;
- do {
- tb->caretpos--;
- } while (IsUtf8Part(*(tb->buf + tb->caretpos)));
-
+ tb->caretpos -= Utf8PrevCharLen(tb->buf + tb->caretpos);
Utf8Decode(&c, tb->buf + tb->caretpos);
tb->caretxoffs -= GetCharacterWidth(FS_NORMAL, c);
--- a/src/string.h Sat Mar 03 22:15:37 2007 +0000
+++ b/src/string.h Sun Mar 04 00:49:40 2007 +0000
@@ -106,6 +106,28 @@
return GB(c, 6, 2) == 2;
}
+/**
+ * Retrieve the (partial) length of the previous UNICODE character
+ * in an UTF-8 encoded string.
+ * @param s char pointer pointing to the first char of the next character
+ * @returns the decoded length in bytes (size) of the UNICODE character
+ * that was just before the one where 's' is pointing to
+ * @note If 's' is not pointing to the first byte of the next UNICODE character
+ * only a partial length of the sequence will be returned.
+ * For example given this sequence: 0xE3 0x85 0x80, 0xE3 0x81 0x9E
+ * 1. 's' is pointing to the second 0xE3, return value is 3
+ * 2. 's' is pointing to 0x80, return value is 2.
+ * So take care with the return values of this function. To get the real length
+ * for an (invalid) sequence, pass the string offset of this function's return
+ * value to Utf8EncodedCharLen() or Utf8Decode()
+ */
+static inline size_t Utf8PrevCharLen(const char *s)
+{
+ size_t len = 1;
+ while (IsUtf8Part(*--s)) len++;
+ return len;
+}
+
static inline bool IsPrintable(WChar c)
{