PyGRUB: fix menu flicker

To avoid flickers, PyGRUB has to avoid spurious ncurses refresh as
much as possible, in particular before the complete screen is drawn,
and eventually call doupdate last.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>

1 files changed, 17 insertions, 15 deletions

diff --git a/tools/pygrub/src/pygrub b/tools/pygrub/src/pygrub
index 48855adc45..ae15af187e 100644
--- a/tools/pygrub/src/pygrub
+++ b/tools/pygrub/src/pygrub
@@ -124,7 +124,7 @@ def get_fs_offset(file):
 class GrubLineEditor(curses.textpad.Textbox):
     def __init__(self, screen, startx, starty, line = ""):
         screen.addstr(startx, starty, "> ")
-        screen.refresh()
+        screen.noutrefresh()
         win = curses.newwin(1, 74, startx, starty + 2)
         curses.textpad.Textbox.__init__(self, win)
         
@@ -137,7 +137,7 @@ class GrubLineEditor(curses.textpad.Textbox):
         """Show the text.  One of our advantages over standard textboxes
         is that we can handle lines longer than the window."""
 
-        self.win.clear()
+        self.win.erase()
         p = self.pos
         off = 0
         while p > 70:
@@ -188,6 +188,7 @@ class GrubLineEditor(curses.textpad.Textbox):
         return 1
 
     def edit(self):
+        curses.doupdate()
         r = curses.textpad.Textbox.edit(self)
         if self.cancelled:
             return None
@@ -217,16 +218,15 @@ class Grub:
             curses.def_prog_mode()
         
         curses.reset_prog_mode()
-        self.screen.clear()
-        self.screen.refresh()
+        self.screen.erase()
 
         # create basic grub screen with a box of entries and a textbox
         self.screen.addstr(1, 4, "pyGRUB  version %s" %(PYGRUB_VER,))
         self.entry_win.box()
-        self.screen.refresh()
+        self.screen.noutrefresh()
 
     def fill_entry_list(self):
-        self.entry_win.clear()
+        self.entry_win.erase()
         self.entry_win.box()
 
         maxy = self.entry_win.getmaxyx()[0]-3 # maxy - 2 for the frame + index
@@ -244,7 +244,7 @@ class Grub:
             self.entry_win.addstr(y + 1 - self.start_image, 2, i.title.ljust(70))
             if y == self.selected_image:
                 self.entry_win.attroff(curses.A_REVERSE)
-        self.entry_win.refresh()
+        self.entry_win.noutrefresh()
 
     def edit_entry(self, origimg):
         def draw():
@@ -259,13 +259,13 @@ class Grub:
             self.text_win.addch(0, 14, curses.ACS_DARROW)
             (y, x) = self.text_win.getmaxyx()
             self.text_win.move(y - 1, x - 1)
-            self.text_win.refresh()
+            self.text_win.noutrefresh()
 
         curline = 1
         img = copy.deepcopy(origimg)
         while 1:
             draw()
-            self.entry_win.clear()
+            self.entry_win.erase()
             self.entry_win.box()
             for idx in range(1, len(img.lines)):
                 # current line should be highlighted
@@ -280,7 +280,8 @@ class Grub:
                 self.entry_win.addstr(idx, 2, l)
                 if idx == curline:
                     self.entry_win.attroff(curses.A_REVERSE)
-            self.entry_win.refresh()
+            self.entry_win.noutrefresh()
+            curses.doupdate()
 
             c = self.screen.getch()
             if c in (ord('q'), 27): # 27 == esc
@@ -318,10 +319,10 @@ class Grub:
             origimg.reset(img.lines)
 
     def edit_line(self, line):
-        self.screen.clear()
+        self.screen.erase()
         self.screen.addstr(1, 2, "[ Minimal BASH-like line editing is supported.  ")
         self.screen.addstr(2, 2, "  ESC at any time cancels.  ENTER at any time accepts your changes. ]")
-        self.screen.refresh()
+        self.screen.noutrefresh()
 
         t = GrubLineEditor(self.screen, 5, 2, line)
         enable_cursor(True)
@@ -331,10 +332,10 @@ class Grub:
         return None
 
     def command_line_mode(self):
-        self.screen.clear()
+        self.screen.erase()
         self.screen.addstr(1, 2, "[ Minimal BASH-like line editing is supported.  ESC at any time ")
         self.screen.addstr(2, 2, "  exits.  Typing 'boot' will boot with your entered commands. ] ")
-        self.screen.refresh()
+        self.screen.noutrefresh()
 
         y = 5
         lines = []
@@ -420,7 +421,7 @@ class Grub:
             self.text_win.addch(0, 14, curses.ACS_DARROW)
             (y, x) = self.text_win.getmaxyx()
             self.text_win.move(y - 1, x - 1)
-            self.text_win.refresh()
+            self.text_win.noutrefresh()
 
         # now loop until we hit the timeout or get a go from the user
         mytime = 0
@@ -433,6 +434,7 @@ class Grub:
             else:
                 self.screen.addstr(20, 5, " " * 80)
             self.fill_entry_list()
+            curses.doupdate()
 
             c = self.screen.getch()
             if c == -1: