apply boxdraw patch for perfect box-drawing character alignment

Applied st-boxdraw_v2-0.8.5.diff with manual adjustments for st 0.9:
- Added boxdraw.c to build sources
- Added ATTR_BOXDRAW attribute flag (bit 13, after ATTR_SELECTED)
- Integrated boxdraw detection in tsetchar() function
- Modified xmakeglyphfontspecs() to use boxdraw for applicable characters
- Adjusted indentation for harfbuzz integration compatibility

Benefits:
- Box-drawing characters now align perfectly regardless of font
- Improved visual quality for tmux, tree, dialog output
- Covers Unicode U2500-U259F (lines/blocks) and U28XX (braille)

1 files changed, 10 insertions, 0 deletions

diff --git a/st.h b/st.h
index d16f417..e320538 100644
--- a/st.h
+++ b/st.h
@@ -36,6 +36,7 @@ enum glyph_attribute {
 	ATTR_WIDE       = 1 << 10,
 	ATTR_WDUMMY     = 1 << 11,
 	ATTR_SELECTED   = 1 << 12,
+	ATTR_BOXDRAW    = 1 << 13,
 	ATTR_BOLD_FAINT = ATTR_BOLD | ATTR_FAINT,
 };
 
@@ -118,6 +119,14 @@ void *xmalloc(size_t);
 void *xrealloc(void *, size_t);
 char *xstrdup(const char *);
 
+int isboxdraw(Rune);
+ushort boxdrawindex(const Glyph *);
+#ifdef XFT_VERSION
+/* only exposed to x.c, otherwise we'll need Xft.h for the types */
+void boxdraw_xinit(Display *, Colormap, XftDraw *, Visual *);
+void drawboxes(int, int, int, int, XftColor *, XftColor *, const XftGlyphFontSpec *, int);
+#endif
+
 /* config.h globals */
 extern char *utmp;
 extern char *scroll;
@@ -131,3 +140,4 @@ extern unsigned int tabspaces;
 extern unsigned int defaultfg;
 extern unsigned int defaultbg;
 extern unsigned int defaultcs;
+extern const int boxdraw, boxdraw_bold, boxdraw_braille;