Initial commit

1 files changed, 76 insertions, 0 deletions

diff --git a/sys/gio/cursor/gtrundo.x b/sys/gio/cursor/gtrundo.x
new file mode 100644
index 00000000..5b8d3e02
--- /dev/null
+++ b/sys/gio/cursor/gtrundo.x
@@ -0,0 +1,76 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<gset.h>
+include	<gio.h>
+include	<gki.h>
+include	"gtr.h"
+
+# GTR_UNDO -- Undo the last frame buffer edit.  Successive pairs of undos leave
+# the frame buffer unchanged.
+
+procedure gtr_undo (stream)
+
+int	stream				# graphics stream
+int	opcode
+pointer	tr, op, new_op, old_op, sp, ap
+
+pointer	gtr_init()
+errchk	gtr_init
+include	"gtr.com"
+
+begin
+	call smark (sp)
+	call salloc (ap, LEN_PL, TY_STRUCT)
+
+	tr = gtr_init (stream)
+
+	old_op = TR_OP(tr)
+	new_op = TR_LASTOP(tr)
+	if (new_op == old_op || new_op <= TR_FRAMEBUF(tr)) {
+	    call sfree (sp)
+	    return
+	}
+
+	# Edit the frame buffer.
+	TR_LASTOP(tr) = old_op
+	TR_OP(tr) = new_op
+	TR_IP(tr) = min (new_op, TR_IP(tr))
+
+	# Redraw the last drawing instruction to erase it (device permitting),
+	# if we are backing up one instruction.  Note that it may be necessary
+	# to skip one or more control instructions.  We assume that the undo
+	# only has to undo one drawing instruction.
+
+	if (new_op < old_op) {
+	    op = new_op
+	    repeat {
+		opcode = Mems[op+GKI_HDR_OPCODE-1]
+		if (opcode == GKI_POLYLINE)
+		    break
+		else
+		    op = op + Mems[op+GKI_HDR_LENGTH-1]
+	    } until (op >= old_op)
+
+	    if (opcode == GKI_POLYLINE && op < old_op) {
+		PL_LTYPE(ap) = GL_CLEAR
+		PL_WIDTH(ap) = 1.0
+		PL_COLOR(ap) = 1
+		call gki_plset (stream, ap)
+
+		if (wstranset == YES)
+		    call gtr_wstran (Mems[op])
+		else
+		    call gki_write (stream, Mems[op])
+
+		PL_LTYPE(ap) = GL_SOLID
+		call gki_plset (stream, ap)
+	    }
+
+	} else if (new_op > old_op) {
+	    # Call giotr to redraw the recovered instructions.
+	    call giotr (stream)
+	}
+
+	call gki_flush (stream)
+	call sfree (sp)
+end