replaced print/exits combinations by sysfatal, to overcome
'unusable' window resulting from fatal error.

(experimental) warp the mouse to the middle of the window
for each new brick that starts dropping - to have sufficient
space left and right to move the falling brick.

(experimental) replaced the white/black blinking when
a row disappears by fading to white - looks nicer.

Axel.

Reference: /n/sources/patch/applied/games-xs-fatal-warp-blink
Date: Thu Jun 16 02:00:26 CES 2005

--- /sys/src/games/xs.h	Thu Jun 16 01:56:40 2005
+++ /sys/src/games/xs.h	Thu Jun 16 01:56:36 2005
@@ -30,6 +30,7 @@
 int		pcsz = 32;
 Point		pos;
 Image	*bb, *bbmask, *bb2, *bb2mask;
+Image	*whitemask;
 Rectangle	br, br2;
 long		points;
 int		dt;
@@ -309,6 +310,7 @@
 		pos.x += nrand(NX)*pcsz;
 	}while(collide(Pt(pos.x, pos.y+pcsz-DY), piece));
 	drawpiece();
+	moveto(mousectl, Pt(rboard.min.x + Dx(rboard)/2, rboard.min.y +Dy(rboard)/2));
 	flushimage(display, 1);
 }
 
@@ -344,7 +346,6 @@
 	int lev[N];
 	int i, j, h;
 	Rectangle r;
-	Image *col;
 
 	h = 0;
 	for(i=0; i<NY; i++){
@@ -361,20 +362,19 @@
 	for(j=0; j<h; j++){
 		r.min.y = rboard.min.y + lev[j]*pcsz;
 		r.max.y = r.min.y + pcsz;
-		draw(screen, r, display->white, nil, ZP);
+		draw(screen, r, display->white, whitemask, ZP);
 		flushimage(display, 1);
 	}
-	for(i=0; i<6; i++){
+	for(i=0; i<5; i++){
 		pause(500);
 		if(newscreen){
 			drawboard();
 			break;
 		}
-		col = (i&1)? display->white : display->black;
 		for(j=0; j<h; j++){
 			r.min.y = rboard.min.y + lev[j]*pcsz;
 			r.max.y = r.min.y + pcsz;
-			draw(screen, r, col, nil, ZP);
+			draw(screen, r, display->white, whitemask, ZP);
 		}
 		flushimage(display, 1);
 	}
@@ -624,10 +624,8 @@
 	Rectangle r;
 	long dx, dy;
 
-	if(new && getwindow(display, Refmesg) < 0){
-		fprint(2, "can't reattach to window");
-		exits("redraw");
-	}
+	if(new && getwindow(display, Refmesg) < 0)
+		sysfatal("can't reattach to window");
 	r = screen->r;
 	pos.x = (pos.x - rboard.min.x) / pcsz;
 	pos.y = (pos.y - rboard.min.y) / pcsz;
@@ -641,11 +639,8 @@
 		DY = 4;
 	pcsz = DY*8;
 	DMOUSE = pcsz/3;
-	if(pcsz < 8){
-		fprint(2, "screen too small: %d\n", pcsz);
-		threadexitsall(nil);
-		exits("too small");
-	}
+	if(pcsz < 8)
+		sysfatal("screen too small: %d", pcsz);
 	rboard = screen->r;
 	rboard.min.x += (dx-pcsz*NX)/2;
 	rboard.min.y += (dy-pcsz*NY)/2+32;
@@ -666,10 +661,8 @@
 	bbmask = allocimage(display, Rect(0,0,N*pcsz,N*pcsz), GREY1, 0, 0);
 	bb2 = allocimage(display, Rect(0,0,N*pcsz,N*pcsz+DY), screen->chan, 0, 0);
 	bb2mask = allocimage(display, bb2->r, GREY1, 0, 0);
-	if(bb==0 || bbmask==0 || bb2==0 || bb2mask==0){
-		fprint(2, "allocimage fail (bb)\n");
-		exits("allocimage");
-	}
+	if(bb==0 || bbmask==0 || bb2==0 || bb2mask==0)
+		sysfatal("allocimage fail (bb)");
 	draw(screen, screen->r, display->white, nil, ZP);
 	drawboard();
 	setpiece(piece);
@@ -695,37 +688,27 @@
 	snprint(buf, sizeof(buf), "%ds", N);
 	initdraw(0, 0, buf);
 	mousectl = initmouse(nil, display->image);	/* BUG? */
-	if(mousectl == nil){
-		fprint(2, "[45]s: mouse init failed: %r\n");
-		exits("mouse");
-	}
+	if(mousectl == nil)
+		sysfatal("[45]s: mouse init failed: %r");
 	keyboardctl = initkeyboard(nil);	/* BUG? */
-	if(keyboardctl == nil){
-		fprint(2, "[45]s: keyboard init failed: %r\n");
-		exits("kbd");
-	}
+	if(keyboardctl == nil)
+		sysfatal("[45]s: keyboard init failed: %r");
 	starttime = time(0);
 	srand(starttime);
 	snprint(buf, sizeof(buf), "/sys/games/lib/%dscores", N);
 	scores = open(buf, OWRITE);
-	if(scores < 0){
-		fprint(2, "can't open %s\n", buf);
-		exits("scores file");
-	}
+	if(scores < 0)
+		sysfatal("can't open %s: %r", buf);
 	tb = 0;
 	if(screen->depth < 3){
 		tb = allocimage(display, Rect(0,0,16,16), 0, 1, -1);
-		if(tb == 0){
-			fprint(2, "allocimage fail (tb)\n");
-			exits("allocimage");
-		}
+		if(tb == 0)
+			sysfatal("allocimage fail (tb)");
 	}
 	for(i = 0; i<NCOL; i++){
 		tx[i] = allocimage(display, Rect(0, 0, 16, 16), screen->chan, 1, txpix[i]);
-		if(tx[i] == 0){
-			fprint(2, "allocimage fail (tx)\n");
-			exits("allocimage");
-		}
+		if(tx[i] == 0)
+			sysfatal("allocimage fail (tx)");
 		if(screen->depth < 3){
 			loadimage(tb, tb->r, txbits[i], 32);
 			draw(tx[i], tx[i]->r, tb, nil, ZP);
@@ -733,6 +716,10 @@
 	}
 	if(tb != 0)
 		freeimage(tb);
+
+	whitemask = allocimage(display, Rect(0,0,1,1), CMAP8, 1, setalpha(DWhite, 0x7F));
+	if(whitemask==0)
+		sysfatal("allocimage fail (whitemask)");
 
 	threadsetname("4s-5s");
 	timerc= chancreate(sizeof(int), 0);