(x_set_toolkit_scroll_bar_thumb, xm_scroll_callback)

(XTread_socket): Undo last change: too late for this release.

2 files changed, 62 insertions, 44 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 08937d032a7..c23034b400b 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2002-03-15  Stefan Monnier  <monnier@cs.yale.edu>
+
+	* xterm.c (x_set_toolkit_scroll_bar_thumb, xm_scroll_callback)
+	(XTread_socket): Undo last change: too late for this release.
+
 2002-03-13  Stefan Monnier  <monnier@cs.yale.edu>
 
 	* xterm.c (x_set_toolkit_scroll_bar_thumb) <USE_MOTIF>:
diff --git a/src/xterm.c b/src/xterm.c
index 73cabf87e41..c3bdefdf65a 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -8521,10 +8521,31 @@ xm_scroll_callback (widget, client_data, call_data)
 	XtVaGetValues (widget, XmNsliderSize, &slider_size, NULL);
 	UNBLOCK_INPUT;
 
-	whole = XM_SB_RANGE - slider_size;
-	portion = min (cs->value - XM_SB_MIN, whole);
-	part = scroll_bar_handle;
-	bar->dragging = make_number (cs->value);
+	/* At the max position of the scroll bar, do a line-wise
+	   movement.  Without doing anything, we would be called with
+	   the same cs->value again and again.  If we want to make
+	   sure that we can reach the end of the buffer, we have to do
+	   something.
+
+	   Implementation note: setting bar->dragging always to
+	   cs->value gives a smoother movement at the max position.
+	   Setting it to nil when doing line-wise movement gives
+	   a better slider behavior. */
+	
+	if (cs->value + slider_size == XM_SB_MAX
+	    || (dragging_down_p
+		&& last_scroll_bar_part == scroll_bar_down_arrow))
+	  {
+	    part = scroll_bar_down_arrow;
+	    bar->dragging = Qnil;
+	  }
+	else
+	  {
+	    whole = XM_SB_RANGE;
+	    portion = min (cs->value - XM_SB_MIN, XM_SB_MAX - slider_size);
+	    part = scroll_bar_handle;
+	    bar->dragging = make_number (cs->value);
+	  }
       }
       break;
       
@@ -8774,27 +8795,7 @@ x_set_toolkit_scroll_bar_thumb (bar, portion, position, whole)
   Widget widget = SCROLL_BAR_X_WIDGET (FRAME_X_DISPLAY (f), bar);
   float top, shown;
 
-  BLOCK_INPUT;
-
-#ifdef USE_MOTIF
-
-  /* We use an estimate of 30 chars per line rather than the real
-     `portion' value.  This has the disadvantage that the thumb size
-     is not very representative, but it makes our life a lot easier.
-     Otherwise, we have to constantly adjust the thumb size, which
-     we can't always do quickly enough: while dragging, the size of
-     the thumb might prevent the user from dragging the thumb all the
-     way to the end.  but Motif and some versions of Xaw3d don't allow
-     updating the thumb size while dragging.  Also, even if we can update
-     its size, the update will often happen too late.
-     If you don't believe it, check out revision 1.650 of xterm.c to see
-     what hoops we were going through and the still poor behavior we got.  */
-  portion = XFASTINT (XWINDOW (bar->window)->height) * 30;
-  /* When the thumb is at the bottom, position == whole.
-     So we need to increase `whole' to make space for the thumb.  */
-  whole += portion;
-
-  if (whole <= 0)
+  if (whole == 0)
     top = 0, shown = 1;
   else
     {
@@ -8802,12 +8803,15 @@ x_set_toolkit_scroll_bar_thumb (bar, portion, position, whole)
       shown = (float) portion / whole;
     }
 
-  if (NILP (bar->dragging))
-    {
-      int size, value;
+  BLOCK_INPUT;
 
-      /* Slider size.  Must be in the range [1 .. MAX - MIN] where MAX
-         is the scroll bar's maximum and MIN is the scroll bar's minimum
+#ifdef USE_MOTIF
+  {
+    int size, value;
+    XmScrollBarWidget sb;
+
+    /* Slider size.  Must be in the range [1 .. MAX - MIN] where MAX
+       is the scroll bar's maximum and MIN is the scroll bar's minimum
 	 value.  */
       size = shown * XM_SB_RANGE;
       size = min (size, XM_SB_RANGE);
@@ -8815,21 +8819,30 @@ x_set_toolkit_scroll_bar_thumb (bar, portion, position, whole)
 
       /* Position.  Must be in the range [MIN .. MAX - SLIDER_SIZE].  */
       value = top * XM_SB_RANGE;
-      value = min (value, XM_SB_MAX - size);
-      value = max (value, XM_SB_MIN);
-      
+    value = min (value, XM_SB_MAX - size);
+    value = max (value, XM_SB_MIN);
+
+    if (NILP (bar->dragging))
       XmScrollBarSetValues (widget, value, size, 0, 0, False);
-    }
+    else if (last_scroll_bar_part == scroll_bar_down_arrow)
+      /* This has the negative side effect that the slider value is
+	 not what it would be if we scrolled here using line-wise or
+	 page-wise movement.  */
+      XmScrollBarSetValues (widget, value, XM_SB_RANGE - value, 0, 0, False);
+    else
+      {
+	/* If currently dragging, only update the slider size.
+	   This reduces flicker effects.  */
+	int old_value, old_size, increment, page_increment;
+	
+	XmScrollBarGetValues (widget, &old_value, &old_size,
+			      &increment, &page_increment);
+	XmScrollBarSetValues (widget, old_value,
+			      min (size, XM_SB_RANGE - old_value),
+			      0, 0, False);
+      }
+  }
 #else /* !USE_MOTIF i.e. use Xaw */
-
-  if (whole == 0)
-    top = 0, shown = 1;
-  else
-    {
-      top = (float) position / whole;
-      shown = (float) portion / whole;
-    }
-
   {
     float old_top, old_shown;
     Dimension height;
@@ -9854,7 +9867,7 @@ static struct x_display_info *next_noop_dpyinfo;
 
    EXPECTED is nonzero if the caller knows input is available.  */
 
-static int
+int
 XTread_socket (sd, bufp, numchars, expected)
      register int sd;
      /* register */ struct input_event *bufp;