better line-rectangle touch check for backward rectangle selection (intersection select)

src/clip.c

@@ -38,6 +38,8 @@ static int outcode(double x,double y, double sx1, double sy1, double sx2, double
  return code;
 }
 
+
+/* clip a line (in screen coordinates) with screen boundaries */
 int clip( double *xa,double *ya,double *xb,double *yb)
 {
  int outa, outb,outpoint;
@@ -74,6 +76,38 @@ int clip( double *xa,double *ya,double *xb,double *yb)
  }
 }
 
+/* clip a line (xa,ya,xb,yb) with rectangle (sx1,sy1,sx2,sy2) */
+int lineclip(double *xa,double *ya,double *xb,double *yb,
+             double sx1,double sy1,double sx2,double sy2)
+{
+ int outa, outb,outpoint;
+ double x,y;
+ outa=outcode(*xa, *ya, sx1, sy1, sx2, sy2);
+ outb=outcode(*xb, *yb, sx1, sy1, sx2, sy2);
+ while(1)
+ {
+  if(!(outa | outb)) return 1;  /* line is all inside! */
+  else if(outa & outb) return 0; /* line is all outside! */
+  else
+  {
+   outpoint=outa? outa:outb;
+   if(UP & outpoint)
+     {x= *xa + (*xb-*xa) * (sy2 - *ya) / (*yb - *ya); y = sy2;}
+   else if(DOWN & outpoint)
+     {x= *xa + (*xb-*xa) * (sy1 - *ya) / (*yb - *ya); y = sy1;}
+   else if(RIGHT & outpoint)
+     {y= *ya + (*yb-*ya) * (sx2 - *xa) / (*xb - *xa); x = sx2;}
+   /* else if(LEFT & outpoint) */
+   else
+     {y= *ya + (*yb-*ya) * (sx1 - *xa) / (*xb - *xa); x = sx1;}
+   if(outpoint == outa)
+     {*xa=x; *ya=y; outa=outcode(*xa, *ya, sx1, sy1, sx2, sy2);}
+   else
+     {*xb=x; *yb=y; outb=outcode(*xb, *yb, sx1, sy1, sx2, sy2);}
+  }
+ }
+}
+
 void clip_xy_to_short(double x, double y, short *sx, short *sy)
 {
   double ax, ay;

src/scheduler.c

@@ -4564,6 +4564,14 @@ int xschem(ClientData clientdata, Tcl_Interp *interp, int argc, const char * arg
       Tcl_ResetResult(interp);
     }
 
+    /* test
+     *   Testmode ... */
+    else if(!strcmp(argv[1], "test") )
+    {
+      if(!xctx) {Tcl_SetResult(interp, not_avail, TCL_STATIC); return TCL_ERROR;}
+      Tcl_ResetResult(interp);
+    }
+
     /* text x y rot flip text props size draw
      *   Create a text object
      *     x, y, rot, flip specify the position and orientation

src/select.c

@@ -1531,8 +1531,12 @@ void select_touch(double x1,double y1, double x2, double y2, int sel) /*added un
 
  for(i=0;i<xctx->wires; ++i)
  {
-  if(POINTINSIDE(xctx->wire[i].x1,xctx->wire[i].y1, x1,y1,x2,y2) || 
-     POINTINSIDE(xctx->wire[i].x2,xctx->wire[i].y2, x1,y1,x2,y2)) {
+  double lx1, ly1, lx2, ly2;
+  lx1 = xctx->wire[i].x1;
+  ly1 = xctx->wire[i].y1;
+  lx2 = xctx->wire[i].x2;
+  ly2 = xctx->wire[i].y2;
+  if(lineclip(&lx1, &ly1, &lx2, &ly2, x1,y1,x2,y2)) {
    xctx->ui_state |= SELECTION; /* set xctx->ui_state to SELECTION also if unselecting by area ???? */
    sel ? select_wire(i,SELECTED, 1): select_wire(i,0, 1);
   }
@@ -1598,8 +1602,12 @@ void select_touch(double x1,double y1, double x2, double y2, int sel) /*added un
    }
    for(i=0;i<xctx->lines[c]; ++i)
    {
-    if(POINTINSIDE(xctx->line[c][i].x1, xctx->line[c][i].y1, x1,y1,x2,y2) ||
-       POINTINSIDE(xctx->line[c][i].x2, xctx->line[c][i].y2, x1,y1,x2,y2)) {
+    double lx1, ly1, lx2, ly2;
+    lx1 = xctx->line[c][i].x1;
+    ly1 = xctx->line[c][i].y1;
+    lx2 = xctx->line[c][i].x2;
+    ly2 = xctx->line[c][i].y2;
+    if(lineclip(&lx1, &ly1, &lx2, &ly2, x1,y1,x2,y2)) {
      xctx->ui_state |= SELECTION;
      sel? select_line(c,i,SELECTED,1): select_line(c,i,0,1);
     }

src/xschem.h

@@ -1352,7 +1352,11 @@ extern void MyXCopyAreaDouble(Display* display, Drawable src, Drawable dest, GC
      double sx1, double sy1, double sx2, double sy2, double dx1, double dy1, double lw);
 extern void draw(void);
 extern void clip_xy_to_short(double x, double y, short *sx, short *sy);
+/* clip a line (in screen coordinates) with screen boundaries */
 extern int clip( double*,double*,double*,double*);
+/* clip a line (xa,ya,xb,yb) with rectangle (sx1,sy1,sx2,sy2) */
+extern int lineclip(double *xa,double *ya,double *xb,double *yb, 
+             double sx1,double sy1,double sx2,double sy2);
 extern int textclip(int x1,int y1,int x2,int y2,
            double xa,double ya,double xb,double yb);
 extern double dist_from_rect(double mx,