patch 9.0.0902: some mouse scroll code is not in a good place

Problem:    Some mouse scroll code is not in a good place.
Solution:   Refactor the code. (Christopher Plewright, closes #11561)

src/mouse.c

@@ -1102,20 +1102,19 @@ ins_mouse(int c)
 }
 
 /*
- * Implementation for scrolling in direction "dir", which is one of the MSCR_
+ * Implementation for scrolling in Insert mode in direction "dir", which is one
- * values.
+ * of the MSCR_ values.
  */
     void
 ins_mousescroll(int dir)
 {
     cmdarg_T	cap;
-    CLEAR_FIELD(cap);
-
     oparg_T	oa;
+    CLEAR_FIELD(cap);
     clear_oparg(&oa);
     cap.oap = &oa;
-
     cap.arg = dir;
+
     switch (dir)
     {
 	case MSCR_UP:
@@ -1133,7 +1132,50 @@ ins_mousescroll(int dir)
 	default:
 	    siemsg("Invalid ins_mousescroll() argument: %d", dir);
     }
-    do_mousescroll(MODE_INSERT, &cap);
+
+    win_T *wp = curwin;
+    if (mouse_row >= 0 && mouse_col >= 0)
+    {
+	// Find the window at the mouse pointer coordinates.
+	int row = mouse_row;
+	int col = mouse_col;
+	wp = mouse_find_win(&row, &col, FIND_POPUP);
+	if (wp == NULL)
+	    return;
+    }
+
+    if (wp == curwin)
+    {
+	// Don't scroll the current window if the popup menu is visible.
+	if (pum_visible())
+	    return;
+
+	undisplay_dollar();
+    }
+
+    linenr_T	orig_topline = wp->w_topline;
+    colnr_T	orig_leftcol = wp->w_leftcol;
+    pos_T	orig_cursor = curwin->w_cursor;
+
+    // The scrolling works almost the same way as in Normal mode.
+    nv_mousescroll(&cap);
+
+    // If the window actually scrolled and the popup menu may overlay the
+    // window, need to redraw it.
+    if ((orig_topline != wp->w_topline || orig_leftcol != wp->w_leftcol)
+	    && pum_visible())
+    {
+	// TODO: Would be more efficient to only redraw the windows that are
+	// overlapped by the popup menu.
+	redraw_all_later(UPD_NOT_VALID);
+	ins_compl_show_pum();
+    }
+
+    if (!EQUAL_POS(curwin->w_cursor, orig_cursor))
+    {
+	start_arrow(&orig_cursor);
+	set_can_cindent(TRUE);
+    }
 }
 
 /*
@@ -2062,32 +2104,29 @@ do_mousescroll_horiz(long_u leftcol)
  *    K_MOUSERIGHT - MSCR_RIGHT
  */
     void
-do_mousescroll(int mode, cmdarg_T *cap)
+nv_mousescroll(cmdarg_T *cap)
 {
-    win_T   *old_curwin = curwin, *wp;
+    win_T   *old_curwin = curwin;
-    int	    did_ins_scroll = FALSE;
-    pos_T   tpos = curwin->w_cursor;
 
     if (mouse_row >= 0 && mouse_col >= 0)
     {
-	int row, col;
+	// Find the window at the mouse pointer coordinates.
-
+	int row = mouse_row;
-	row = mouse_row;
+	int col = mouse_col;
-	col = mouse_col;
+	win_T *wp = mouse_find_win(&row, &col, FIND_POPUP);
-
-	// find the window at the pointer coordinates
-	wp = mouse_find_win(&row, &col, FIND_POPUP);
 	if (wp == NULL)
 	    return;
 #ifdef FEAT_PROP_POPUP
 	if (WIN_IS_POPUP(wp) && !wp->w_has_scrollbar)
+	    // cannot scroll this popup window
 	    return;
 #endif
+	// NOTE: Must restore "curwin" to "old_curwin" before returning!
 	curwin = wp;
 	curbuf = curwin->w_buffer;
     }
-    if (mode == MODE_INSERT && curwin == old_curwin)
+
-	undisplay_dollar();
+    int shift_or_ctrl = mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL);
 
 #ifdef FEAT_TERMINAL
     if (term_use_loop())
@@ -2096,35 +2135,23 @@ do_mousescroll(int mode, cmdarg_T *cap)
 	send_keys_to_term(curbuf->b_term, cap->cmdchar, mod_mask, FALSE);
     else
 #endif
-    // For Insert mode, don't scroll the window in which completion is being
-    // done.
-    if (mode == MODE_NORMAL || !pum_visible() || curwin != old_curwin)
-    {
     if (cap->arg == MSCR_UP || cap->arg == MSCR_DOWN)
     {
-	    if (mouse_vert_step < 0
+	// Vertical scrolling
-		    || mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
+	if (!(State & MODE_INSERT) && (mouse_vert_step < 0 || shift_or_ctrl))
 	{
-		if (mode == MODE_INSERT)
+	    // whole page up or down
-		{
+	    onepage(cap->arg == MSCR_UP ? FORWARD : BACKWARD, 1L);
-		    long step = (long)(curwin->w_botline - curwin->w_topline);
-		    scroll_redraw(cap->arg, step);
 	}
 	else
 	{
-		    did_ins_scroll = onepage(cap->arg ? FORWARD : BACKWARD, 1L);
+	    if (mouse_vert_step < 0 || shift_or_ctrl)
-		}
-	    }
-	    else
 	    {
-		if (mode == MODE_INSERT)
+		// whole page up or down
-		{
+		cap->count1 = (long)(curwin->w_botline - curwin->w_topline);
-		    scroll_redraw(cap->arg, mouse_vert_step);
 	    }
-		else
-		{
 	    // Don't scroll more than half the window height.
-		    if (curwin->w_height < mouse_vert_step * 2)
+	    else if (curwin->w_height < mouse_vert_step * 2)
 	    {
 		cap->count1 = curwin->w_height / 2;
 		if (cap->count1 == 0)
@@ -2137,7 +2164,6 @@ do_mousescroll(int mode, cmdarg_T *cap)
 	    cap->count0 = cap->count1;
 	    nv_scroll_line(cap);
 	}
-	    }
 
 #ifdef FEAT_PROP_POPUP
 	if (WIN_IS_POPUP(curwin))
@@ -2146,20 +2172,18 @@ do_mousescroll(int mode, cmdarg_T *cap)
     }
     else
     {
-	    long step = (mouse_hor_step < 0
+	// Horizontal scrolling
-			      || (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL)))
+	long step = (mouse_hor_step < 0 || shift_or_ctrl)
 					    ? curwin->w_width : mouse_hor_step;
 	long leftcol = curwin->w_leftcol
 				     + (cap->arg == MSCR_RIGHT ? -step : step);
 	if (leftcol < 0)
 	    leftcol = 0;
-
+	do_mousescroll_horiz((long_u)leftcol);
-	    did_ins_scroll = do_mousescroll_horiz((long_u)leftcol);
-	}
     }
 
 #ifdef FEAT_SYN_HL
-    if (mode == MODE_NORMAL && curwin != old_curwin && curwin->w_p_cul)
+    if (curwin != old_curwin && curwin->w_p_cul)
 	redraw_for_cursorline(curwin);
 #endif
     may_trigger_winscrolled();
@@ -2168,29 +2192,6 @@ do_mousescroll(int mode, cmdarg_T *cap)
 
     curwin = old_curwin;
     curbuf = curwin->w_buffer;
-
-    if (mode == MODE_INSERT)
-    {
-	// The popup menu may overlay the window, need to redraw it.
-	// TODO: Would be more efficient to only redraw the windows that are
-	// overlapped by the popup menu.
-	if (pum_visible() && did_ins_scroll)
-	{
-	    redraw_all_later(UPD_NOT_VALID);
-	    ins_compl_show_pum();
-	}
-	if (!EQUAL_POS(curwin->w_cursor, tpos))
-	{
-	    start_arrow(&tpos);
-	    set_can_cindent(TRUE);
-	}
-    }
-}
-
-    void
-nv_mousescroll(cmdarg_T *cap)
-{
-    do_mousescroll(MODE_NORMAL, cap);
 }
 
 /*
@@ -3162,6 +3163,9 @@ vcol2col(win_T *wp, linenr_T lnum, int vcol)
 #endif
 
 #if defined(FEAT_EVAL) || defined(PROTO)
+/*
+ * "getmousepos()" function.
+ */
     void
 f_getmousepos(typval_T *argvars UNUSED, typval_T *rettv)
 {

src/proto/mouse.pro

@@ -15,7 +15,6 @@ int mouse_model_popup(void);
 void reset_dragwin(void);
 int jump_to_mouse(int flags, int *inclusive, int which_button);
 int do_mousescroll_horiz(long_u leftcol);
-void do_mousescroll(int mode, cmdarg_T *cap);
 void nv_mousescroll(cmdarg_T *cap);
 void nv_mouse(cmdarg_T *cap);
 void reset_held_button(void);

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    902,
 /**/
     901,
 /**/