So far, that's what it seems to mean. I'm trying to
get some constructive discussion going about it.
Bob
----- Original Message -----
Sent: Friday, April 05, 2002 11:13
AM
Subject: Re: [platform-swt-dev] no
background on GTK
Does this mean that SWT
doesn't provide a means to implement a transparent canvas (without dipping
into platform code)?
David
-- David Whiteman OTI Raleigh david_whiteman@xxxxxxx
SWT.NO_BACKGROUND stops the control from automatically
being filled with the background color. The idea is that
application code can get rid of flashing by painting the whole window
once instead of erasing
and then painting.
On
Windows, we makeWM_ERASEBKGND do nothing. On X, we convince the server
not to fill the X window.
On GTK ... we call gdk_window_set_back_pixmap()which is spec'd to behave the same as X but
this doesn't seem to work.
Steve
| "Bob Foster"
<bob@xxxxxxxxxx> Sent by: platform-swt-dev-admin@xxxxxxxxxxx
04/04/02 05:53 PM Please respond to
platform-swt-dev
|
To:
<platform-swt-dev@xxxxxxxxxxx>
cc:
Subject: Re: [platform-swt-dev] no
background on GTK |
This raises the question: What is SWT.NO_BACKGROUND is supposed
to do? Let's say you set up a Canvas with no background that is "in front
of" another widget (drawn last). Shouldn't the other widget show through
the canvas? Instead, it appears that the widget in back is not drawn at
all, which means that nothing is drawn and the desktop shows through the
window.
I need a transparent canvas for my application. Why
doesn't SWT.NO_BACKGROUND give me that?
Bob Object Factory
Inc.
----- Original Message ----- From:
<Silenio_Quarti@xxxxxxx> To:
<platform-swt-dev@xxxxxxxxxxx> Sent: Thursday, April 04, 2002 3:24
PM Subject: [platform-swt-dev] no background on GTK
>
Havoc, > > We are trying to implement the SWT.NO_BACKGROUND style.
This > style determines with a widget will fill the background
when > an expose event happens. > > On X, it is possible to
do this by setting the background > pixmap of a Window to
None. > > On GTK, the equivalent API is
gdk_window_set_back_pixmap(). > > If you run the test below, you
will see that the shell > will fill its background even though the test
is setting > the back pixmap to NULL. > > It seems that the
background is not filled by X, but it is > been filled by GTK. Havoc is
there a away of avoiding this? > > Silenio > > >
Here is some code that shows the problem: > > public class
NoBackgroundTest { > > public static void main (String [] args)
throws Exception { > OS.gtk_init_check (new
int [] {0}, null); > > int shellHandle
= OS.gtk_window_new (OS.GTK_WINDOW_TOPLEVEL); > >
OS.gtk_widget_realize(shellHandle); > >
int window = OS.GTK_WIDGET_WINDOW(shellHandle); >
OS.gdk_window_set_back_pixmap(window, 0,
false); > >
OS.gtk_widget_show(shellHandle); > >
while (OS.gtk_main_iteration() != 0); > } > } >
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