[dev] [st] Scroll selection patch

[Rafa Garcia Gallego]

Hi,

One thing from st that bugs me a little: whenever I select some text
with the mouse it remains marked even if I type in the same line and
change its content. The same happens if I keep typing and the window
scrolls, since the selection box does not scroll along with it. In
either case, a new piece of text seems to be selected, but this "new
selection" is of course not copied to the clipboard, which feels
annoying.

This patch solves this problem with a behavior akin to that of
xterm/urxvt: scrolling the selection box with the screen and hiding it
if you type in its line or clear the screen.

Cheers,
Rafa

PS: I tried looking both at xterm and urxvt source for a minute;
almost ripped my eyes off

diff -r 1c8e6796c6fe st.c
--- a/st.c      Sun Aug 14 17:15:19 2011 +0200
+++ b/st.c      Wed Sep 14 15:38:20 2011 +0200
@@ -231,6 +231,7 @@
 static inline int selected(int, int);
 static void selcopy(void);
 static void selpaste();
+static void scrollsel(int, int);
 
 static int utf8decode(char *, long *);
 static int utf8encode(long *, char *);
@@ -801,6 +802,8 @@
                term.line[i] = term.line[i-n];
                term.line[i-n] = temp;
        }
+
+       scrollsel(orig, n);
 }
 
 void
@@ -816,6 +819,29 @@
                 term.line[i] = term.line[i+n];
                 term.line[i+n] = temp;
        }
+
+       scrollsel(orig, -n);
+}
+
+void
+scrollsel(int orig, int n) {
+       if(sel.bx == -1) return;
+       if(BETWEEN(sel.by, orig, term.bot) || BETWEEN(sel.ey, orig, term.bot)) {
+               if((sel.by+=n) > term.bot || (sel.ey+=n) < term.top) {
+                       sel.bx=-1;
+                       return;
+               }
+               if(sel.by<term.top) {
+                       sel.by=term.top;
+                       sel.bx=0;
+               }
+               if(sel.ey>term.bot) {
+                       sel.ey=term.bot;
+                       sel.ex=term.col;
+               }
+               sel.b.y=sel.by; sel.b.x=sel.bx;
+               sel.e.y=sel.ey; sel.e.x=sel.ex;
+       }
 }
 
 void
@@ -1072,6 +1098,7 @@
                break;
        /* XXX: (CSI n I) CHT -- Cursor Forward Tabulation <n> tab stops */
        case 'J': /* ED -- Clear screen */
+               sel.bx = -1;
                switch(escseq.arg[0]) {
                case 0: /* below */
                        tclearregion(term.c.x, term.c.y, term.col-1, term.c.y);
@@ -1377,6 +1404,7 @@
                        }
                }
        } else {
+               if(sel.bx != -1 && BETWEEN(term.c.y, sel.by, sel.ey)) sel.bx = 
-1;
                switch(ascii) {
                case '\t':
                        tputtab();