[Xen-devel] [PATCH] PyGRUB: fix menu flicker

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>

diff -r c2472ded5c7c tools/pygrub/src/pygrub
--- a/tools/pygrub/src/pygrub   Tue Aug 26 15:16:57 2008 +0100
+++ b/tools/pygrub/src/pygrub   Tue Aug 26 17:06:09 2008 +0100
@@ -124,7 +124,7 @@ class GrubLineEditor(curses.textpad.Text
 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.Text
         """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.Text
         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:

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