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(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.

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This commit is contained in:
Darkvater
2007-03-04 00:49:40 +00:00
parent 09333fde60
commit 4c912e462c
2 changed files with 24 additions and 9 deletions
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11
src/misc_gui.cpp
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@@ -805,11 +805,7 @@ static void DelChar(Textbuf *tb, bool backspace)
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 @@ bool MoveTextBufferPos(Textbuf *tb, int navmode)
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);

22
src/string.h
View File

@@ -106,6 +106,28 @@ static inline bool IsUtf8Part(char c)
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)
{