Move terminal-related selection logic into st.c

The front-end determines information about mouse clicks and motion, and
the terminal handles the actual selection start/extend/dirty logic by
row and column.

While we're in the neighborhood, we'll also rename getbuttoninfo() to
mousesel() which is, at least, less wrong.

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

3 files changed, 54 insertions, 41 deletions

diff --git a/st.c b/st.c
index ea0726c..21cba9e 100644
--- a/st.c
+++ b/st.c
@@ -140,6 +140,7 @@ static void tscrollup(int, int);
 static void tscrolldown(int, int);
 static void tsetattr(int *, int);
 static void tsetchar(Rune, Glyph *, int, int);
+static void tsetdirt(int, int);
 static void tsetscroll(int, int);
 static void tswapscreen(void);
 static void tsetmode(int, int, int *, int);
@@ -385,6 +386,42 @@ tlinelen(int y)
 }
 
 void
+selstart(int col, int row, int snap)
+{
+        selclear();
+        sel.mode = SEL_EMPTY;
+        sel.type = SEL_REGULAR;
+        sel.snap = snap;
+        sel.oe.x = sel.ob.x = col;
+        sel.oe.y = sel.ob.y = row;
+        selnormalize();
+
+        if (sel.snap != 0)
+                sel.mode = SEL_READY;
+        tsetdirt(sel.nb.y, sel.ne.y);
+}
+
+void
+selextend(int col, int row, int type)
+{
+        int oldey, oldex, oldsby, oldsey, oldtype;
+        oldey = sel.oe.y;
+        oldex = sel.oe.x;
+        oldsby = sel.nb.y;
+        oldsey = sel.ne.y;
+        oldtype = sel.type;
+
+        sel.alt = IS_SET(MODE_ALTSCREEN);
+        sel.oe.x = col;
+        sel.oe.y = row;
+        selnormalize();
+        sel.type = type;
+
+        if (oldey != sel.oe.y || oldex != sel.oe.x || oldtype != sel.type)
+                tsetdirt(MIN(sel.nb.y, oldsby), MAX(sel.ne.y, oldsey));
+}
+
+void
 selnormalize(void)
 {
         int i;
diff --git a/st.h b/st.h
index 79dd47e..c5ff5cf 100644
--- a/st.h
+++ b/st.h
@@ -172,7 +172,6 @@ void toggleprinter(const Arg *);
 int tattrset(int);
 void tnew(int, int);
 void tresize(int, int);
-void tsetdirt(int, int);
 void tsetdirtattr(int);
 void ttynew(char *, char *, char **);
 size_t ttyread(void);
@@ -184,6 +183,8 @@ void resettitle(void);
 
 void selclear(void);
 void selinit(void);
+void selstart(int, int, int);
+void selextend(int, int, int);
 void selnormalize(void);
 int selected(int, int);
 char *getsel(void);
diff --git a/x.c b/x.c
index 9f506b1..ddae6b6 100644
--- a/x.c
+++ b/x.c
@@ -157,7 +157,7 @@ static void selnotify(XEvent *);
 static void selclear_(XEvent *);
 static void selrequest(XEvent *);
 static void setsel(char *, Time);
-static void getbuttoninfo(XEvent *);
+static void mousesel(XEvent *);
 static void mousereport(XEvent *);
 static char *kmap(KeySym, uint);
 static int match(uint, uint);
@@ -313,24 +313,19 @@ y2row(int y)
 }
 
 void
-getbuttoninfo(XEvent *e)
+mousesel(XEvent *e)
 {
-        int type;
+        int type, seltype = SEL_REGULAR;
         uint state = e->xbutton.state & ~(Button1Mask | forceselmod);
 
-        sel.alt = IS_SET(MODE_ALTSCREEN);
-
-        sel.oe.x = x2col(e->xbutton.x);
-        sel.oe.y = y2row(e->xbutton.y);
-        selnormalize();
-
-        sel.type = SEL_REGULAR;
         for (type = 1; type < LEN(selmasks); ++type) {
                 if (match(selmasks[type], state)) {
-                        sel.type = type;
+                        seltype = type;
                         break;
                 }
         }
+
+        selextend(x2col(e->xbutton.x), y2row(e->xbutton.y), seltype);
 }
 
 void
@@ -402,6 +397,7 @@ bpress(XEvent *e)
 {
         struct timespec now;
         MouseShortcut *ms;
+        int snap;
 
         if (IS_SET(MODE_MOUSE) && !(e->xbutton.state & forceselmod)) {
                 mousereport(e);
@@ -417,33 +413,22 @@ bpress(XEvent *e)
         }
 
         if (e->xbutton.button == Button1) {
-                clock_gettime(CLOCK_MONOTONIC, &now);
-
-                /* Clear previous selection, logically and visually. */
-                selclear_(NULL);
-                sel.mode = SEL_EMPTY;
-                sel.type = SEL_REGULAR;
-                sel.oe.x = sel.ob.x = x2col(e->xbutton.x);
-                sel.oe.y = sel.ob.y = y2row(e->xbutton.y);
-
                 /*
                  * If the user clicks below predefined timeouts specific
                  * snapping behaviour is exposed.
                  */
+                clock_gettime(CLOCK_MONOTONIC, &now);
                 if (TIMEDIFF(now, xsel.tclick2) <= tripleclicktimeout) {
-                        sel.snap = SNAP_LINE;
+                        snap = SNAP_LINE;
                 } else if (TIMEDIFF(now, xsel.tclick1) <= doubleclicktimeout) {
-                        sel.snap = SNAP_WORD;
+                        snap = SNAP_WORD;
                 } else {
-                        sel.snap = 0;
+                        snap = 0;
                 }
-                selnormalize();
-
-                if (sel.snap != 0)
-                        sel.mode = SEL_READY;
-                tsetdirt(sel.nb.y, sel.ne.y);
                 xsel.tclick2 = xsel.tclick1;
                 xsel.tclick1 = now;
+
+                selstart(x2col(e->xbutton.x), y2row(e->xbutton.y), snap);
         }
 }
 
@@ -649,20 +634,17 @@ brelease(XEvent *e)
                 selpaste(NULL);
         } else if (e->xbutton.button == Button1) {
                 if (sel.mode == SEL_READY) {
-                        getbuttoninfo(e);
+                        mousesel(e);
                         setsel(getsel(), e->xbutton.time);
                 } else
                         selclear_(NULL);
                 sel.mode = SEL_IDLE;
-                tsetdirt(sel.nb.y, sel.ne.y);
         }
 }
 
 void
 bmotion(XEvent *e)
 {
-        int oldey, oldex, oldsby, oldsey;
-
         if (IS_SET(MODE_MOUSE) && !(e->xbutton.state & forceselmod)) {
                 mousereport(e);
                 return;
@@ -672,14 +654,7 @@ bmotion(XEvent *e)
                 return;
 
         sel.mode = SEL_READY;
-        oldey = sel.oe.y;
-        oldex = sel.oe.x;
-        oldsby = sel.nb.y;
-        oldsey = sel.ne.y;
-        getbuttoninfo(e);
-
-        if (oldey != sel.oe.y || oldex != sel.oe.x)
-                tsetdirt(MIN(sel.nb.y, oldsby), MAX(sel.ne.y, oldsey));
+        mousesel(e);
 }
 
 void