libui/windows/graphemes.cpp

61 lines
1.8 KiB
C++

// 25 may 2016
#include "uipriv_windows.hpp"
#include "attrstr.hpp"
// We could use CharNextW() to generate grapheme cluster boundaries, but it doesn't handle surrogate pairs properly (see http://archives.miloush.net/michkap/archive/2008/12/16/9223301.html).
// We could also use Uniscribe (see http://archives.miloush.net/michkap/archive/2005/01/14/352802.html, http://www.catch22.net/tuts/uniscribe-mysteries, http://www.catch22.net/tuts/keyboard-navigation, and https://maxradi.us/documents/uniscribe/), but its rules for buffer sizes is convoluted.
// Let's just deal with the CharNextW() bug.
int uiprivGraphemesTakesUTF16(void)
{
return 1;
}
uiprivGraphemes *uiprivNewGraphemes(void *s, size_t len)
{
uiprivGraphemes *g;
WCHAR *str;
size_t *pPTG, *pGTP;
g = uiprivNew(uiprivGraphemes);
g->len = 0;
str = (WCHAR *) s;
while (*str != L'\0') {
g->len++;
str = CharNextW(str);
// no need to worry about surrogates if we're just counting
}
g->pointsToGraphemes = (size_t *) uiprivAlloc((len + 1) * sizeof (size_t), "size_t[] (graphemes)");
g->graphemesToPoints = (size_t *) uiprivAlloc((g->len + 1) * sizeof (size_t), "size_t[] (graphemes)");
pPTG = g->pointsToGraphemes;
pGTP = g->graphemesToPoints;
str = (WCHAR *) s;
while (*str != L'\0') {
WCHAR *next, *p;
ptrdiff_t nextoff;
// as part of the bug, we need to make sure we only call CharNextW() on low halves, otherwise it'll return the same low half forever
nextoff = 0;
if (IS_HIGH_SURROGATE(*str))
nextoff = 1;
next = CharNextW(str + nextoff);
if (IS_LOW_SURROGATE(*next))
next--;
*pGTP = pPTG - g->pointsToGraphemes;
for (p = str; p < next; p++)
*pPTG++ = pGTP - g->graphemesToPoints;
pGTP++;
str = next;
}
// and handle the last item for the end of the string
*pGTP = pPTG - g->pointsToGraphemes;
*pPTG = pGTP - g->graphemesToPoints;
return g;
}