| Subject: | Curses::UI and background color [PATCH] [WORKAROUND] |
| Date: | Thu, 1 Oct 2009 14:29:13 +0200 |
| To: | bug-Curses-UI [...] rt.cpan.org |
| From: | Miquel van Smoorenburg <mikevs [...] xs4all.net> |
I implemented a simple test application with Curses::UI
and color, and I noticed that the background color in a window
is not set correctly if it is not initialized (i.e. if nothing
is drawn on it by the application or a widget).
This is also true for the main Curses::UI window, the background
is not initialized.
You can see the same thing happening with the sample color_editor
application.
I've tested this on the linux console, in an xterm, and
in gnome-terminal. I'm using Curses::UI 0.9605 as found in
debian and ubuntu.
It took me a whole lot of searching, but I finally found the
root cause: a missing bkgdset().
With this, I created a workaround that can be used in scripts
that use Curses::UI
Include the fixupbg() function below in you script and
call it every time a curses window is initialized.
sub fixupbg {
my $win = shift;
return if (!$Curses::UI::color_support);
my $co = $Curses::UI::color_object;
foreach my $object ($win, values %{$win->{-id2object}}) {
my $scr = defined $object->{-borderscr}
? $object->{-borderscr}
: $object->{-canvasscr};
next unless defined $scr;
my $pair = $co->get_color_pair($object->{-fg}, $object->{-bg});
$scr->bkgdset(COLOR_PAIR($pair) | 32);
}
}
Use it like this:
my $cui = new Curses::UI( -color_support => 1, -fg => 'black', -bg => 'white' );
fixupbg($cui);
my $dialog = $cui->add( ... );
fixupbg($dialog);
I've also fixed Curses::UI itself, which makes the above
workaround unnecessary. Curses::UI needs to call bkgdset()
internally after a curses window is initialized.
I've attached a patch that does this in the draw() method. It is
a bit of overkill since it's probably only necessary once, but
otherwise the patch would become more complicated - you'd need
to call bkgdset every time -bg is updated, for example in
all set_color_bg() functions, UI::set_color, etc. Perhaps the
maintainer can fix it the 'right' way eventually.
--- Widget.pm.ORIG 2008-03-03 06:30:35.000000000 +0100
+++ Widget.pm 2009-04-27 12:53:54.000000000 +0200
@@ -537,6 +537,12 @@
? $this->{-borderscr}
: $this->{-canvasscr};
return unless defined $scr;
+
+ if ($Curses::UI::color_support) {
+ my $co = $Curses::UI::color_object;
+ my $pair = $co->get_color_pair( $this->{-fg}, $this->{-bg} );
+ $scr->bkgdset(COLOR_PAIR($pair) | 32) if ($pair);
+ }
$scr->erase;
$scr->noutrefresh();
Mike.