From f2bfdefe45b149e03d0c1c66bd74bacb8f130e05 Mon Sep 17 00:00:00 2001
From: Ben Harris <bjh21@bjh21.me.uk>
Date: Sat, 7 Dec 2002 15:21:56 +0000
Subject: [PATCH] When scrolling part of the window, scroll the update region
 as well so that parts that haven't been painted yet still get an update event
 in their new location.  This code seems far too complicated, and I suspect
 there's a better way.  Still, scrolling continuously with the window
 partially off-screen now works.

[originally from svn r2284]
---
 mac/macterm.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/mac/macterm.c b/mac/macterm.c
index daed7f6f..062f8c12 100644
--- a/mac/macterm.c
+++ b/mac/macterm.c
@@ -1,4 +1,4 @@
-/* $Id: macterm.c,v 1.16 2002/11/29 00:32:03 ben Exp $ */
+/* $Id: macterm.c,v 1.17 2002/12/07 15:21:56 ben Exp $ */
 /*
  * Copyright (c) 1999 Simon Tatham
  * Copyright (c) 1999, 2002 Ben Harris
@@ -1269,20 +1269,46 @@ void palette_reset(void *frontend) {
 void do_scroll(void *frontend, int topline, int botline, int lines) {
     Session *s = frontend;
     Rect r;
-    RgnHandle update;
+    RgnHandle scrollrgn = NewRgn();
+    RgnHandle movedupdate = NewRgn();
+    RgnHandle update = NewRgn();
+    Point g2l = { 0, 0 };
 
     SetPort(s->window);
+
+    /*
+     * Work out the part of the update region that will scrolled by
+     * this operation.
+     */
+    if (lines > 0)
+	SetRectRgn(scrollrgn, 0, (topline + lines) * s->font_height,
+		   s->term->cols * s->font_width,
+		   (botline + 1) * s->font_height);
+    else
+	SetRectRgn(scrollrgn, 0, topline * s->font_height,
+		   s->term->cols * s->font_width,
+		   (botline - lines + 1) * s->font_height);
+    CopyRgn(((WindowPeek)s->window)->updateRgn, movedupdate);
+    GlobalToLocal(&g2l);
+    OffsetRgn(movedupdate, g2l.h, g2l.v); /* Convert to local co-ords. */
+    SectRgn(scrollrgn, movedupdate, movedupdate); /* Clip scrolled section. */
+    ValidRgn(movedupdate);
+    OffsetRgn(movedupdate, 0, -lines * s->font_height); /* Scroll it. */
+
     PenNormal();
     if (HAVE_COLOR_QD())
 	PmBackColor(DEFAULT_BG);
     else
 	BackColor(blackColor); /* XXX make configurable */
-    update = NewRgn();
     SetRect(&r, 0, topline * s->font_height,
 	    s->term->cols * s->font_width, (botline + 1) * s->font_height);
     ScrollRect(&r, 0, - lines * s->font_height, update);
-    /* XXX: move update region? */
+
     InvalRgn(update);
+    InvalRgn(movedupdate);
+
+    DisposeRgn(scrollrgn);
+    DisposeRgn(movedupdate);
     DisposeRgn(update);
 }