Right, I think we now hove scrolling optimisations. They should probably be

conditional on something, but I can't be bothered right now.

[originally from svn r67]

macterm.c

@@ -1,4 +1,4 @@
-/* $Id: macterm.c,v 1.1.2.11 1999/03/02 14:52:35 ben Exp $ */
+/* $Id: macterm.c,v 1.1.2.12 1999/03/02 21:51:55 ben Exp $ */
 /*
  * Copyright (c) 1999 Ben Harris
  * All rights reserved.
@@ -494,3 +494,23 @@ void optimised_move(int to, int from, int lines) {
     InvalRgn(update); /* XXX: necessary?  probably harmless anyway */
     DisposeRgn(update);
 }
+
+
+/*
+ * Scroll the screen. (`lines' is +ve for scrolling forward, -ve
+ * for backward.)
+ */
+void do_scroll(int topline, int botline, int lines) {
+    struct mac_session *s = onlysession;
+    Rect r;
+    RgnHandle update;
+
+    SetPort(s->window);
+    update = NewRgn();
+    SetRect(&r, 0, topline * font_height,
+	    cols * font_width, (botline + 1) * font_height);
+    ScrollRect(&r, 0, - lines * font_height, update);
+    /* XXX: move update region? */
+    InvalRgn(update);
+    DisposeRgn(update);
+}

putty.h

@@ -196,6 +196,7 @@ void palette_reset (void);
 void write_clip (void *, int);
 void get_clip (void **, int *);
 void optimised_move (int, int, int);
+void do_scroll(int, int, int);
 void fatalbox (const char *, ...);
 void beep (void);
 #define OPTIMISE_IS_SCROLL 1

terminal.c

@@ -97,6 +97,7 @@ static void erase_lots (int, int, int);
 static void swap_screen (int);
 static void update_sbar (void);
 static void deselect (void);
+static void scroll_display(int, int, int);
 
 /*
  * Set up power-on settings for the terminal.
@@ -400,10 +401,30 @@ static void scroll (int topline, int botline, int lines, int sb) {
 		selend = scroll_top + size + scroll_size;
 	}
     }
-
+    scroll_display(topline, botline, lines);
-    scroll_heuristic += lines;
 }
 
+static void scroll_display(int topline, int botline, int lines) {
+    unsigned long *start, *end;
+    int distance, size, i;
+
+    start = disptext + topline * (cols + 1);
+    end = disptext + (botline + 1) * (cols + 1);
+    distance = (lines > 0 ? lines : -lines) * (cols + 1);
+    size = end - start - distance;
+    if (lines > 0) {
+	memmove(start, start + distance, size * TSIZE);
+	for (i = 0; i < distance; i++)
+	    (start + size)[i] |= ATTR_INVALID;
+    } else {
+	memmove(start + distance, start, size * TSIZE);
+	for (i = 0; i < distance; i++)
+	    start[i] |= ATTR_INVALID;
+    }
+    do_scroll(topline, botline, lines);
+}
+    
+
 /*
  * Move the cursor to a given position, clipping at boundaries. We
  * may or may not want to clip at the scroll margin: marg_clip is 0
@@ -1282,6 +1303,8 @@ void term_scroll (int rel, int where) {
     if (disptop > scrtop)
 	disptop = scrtop;
     update_sbar();
+    if (rel == 0 && where < rows && where > -rows)
+	scroll_display(0, rows - 1, where);
     term_update();
 }