[Mono-winforms-list] Double Buffering

Tue, 3 May 2005 16:45:00 -0400

	Maybe weirdness was the wrong word. Sometimes I hit things that
are not implemented (which is fine, and maybe I could even look into
these things). Right now I am mainly seeing issues with
Regions/Clipping, as this is what I am trying to use.

Thanks for the advice,
Jonathan =20

-----Original Message-----
From: Peter Dennis Bartok [mailto:peter@novonyx.com]=20
Sent: Tuesday, May 03, 2005 4:39 PM
To: Jonathan S. Chambers; mono-winforms-list@lists.ximian.com
Subject: Re: [Mono-winforms-list] Double Buffering

To debug unmanaged code I use gdb. A few mono-specific gdb things I do:

Make sure your ~/.gdbinit contains this line:
handle SIGPWR SIGXCPU noprint nostop pass

Run the mono app inside gdb:
gdb --args mono app.exe <app args>

Set a breakpoint in unmanaged code:
break <function> (e.g. break MeasureOrDrawString)
Answer y on this question:Make breakpoint pending on future shared
library=20
load? (y or [n]))

Find out where you are:
bt (or, if it crashed, you might want to do 'thread apply all bt' to get
a=20
backtrace on all threads)

Translate an address on the stack into a managed method:
print print_method_from_ip(address)

Example:
(gdb) bt
#0  gdip_graphics_init (graphics=3D0x966d258) at graphics.c:42
#1  0x00470a7d in gdip_graphics_new () at graphics.c:71
#2  0x004808ac in GdipGetImageGraphicsContext (image=3D0x9668280,=20
graphics=3D0xfef72e30) at image.c:131
#3  0x00209960 in ?? ()
#4  0x09668280 in ?? ()
#5  0xfef72e30 in ?? ()
#6  0x000c87a0 in ?? ()
#7  0x092573e8 in ?? ()
#8  0x090c87b8 in ?? ()
#9  0x090c87a0 in ?? ()
#10 0x0966bf80 in ?? ()
#11 0x00000000 in ?? ()
(gdb) print print_method_from_ip (0x00209960)
IP 0x209960 at offset 0x30 of method (wrapper managed-to-native)=20
System.Drawing.GDIPlus:GdipGetImageGraphicsContext (intptr,intptr&)=20
(0x209930 0x209984)[domain 0x9108f00 - text.exe]
$3 =3D void

With a little bit of practice you can pick out which numbers are managed

function addresses

Hope this helps.

What kind of System.Drawing weirdness are you experiencing?

Cheers,
  Peter

-----Original Message-----
From: "Jonathan S. Chambers" <Jonathan.Chambers@ansys.com>
To: "Peter Dennis Bartok" <peter@novonyx.com>;=20
<mono-winforms-list@lists.ximian.com>
Date: 03 May, 2005 14:27
Subject: RE: [Mono-winforms-list] Double Buffering

Yes, I'm using double buffering in the property grid now. With
the change to Control.cs to support double buffering it was easy, as
well as changing the code to override OnPaint instead of WndProc.
I've done a decent bit of .Net development, but very little
native linux development. I'm trying to draw the control as efficiently
as possible but seem to run into quirks in System.Drawing (which is
forwarding calls to unmanaged code). Any advice for debugging unmanaged
code on Linux? I've been spoiled by my years of using the Visual Studio
IDE on Windows.

Thanks,
Jonathan

-----Original Message-----
From: Peter Dennis Bartok [mailto:peter@novonyx.com]
Sent: Tuesday, May 03, 2005 4:19 PM
To: Jonathan S. Chambers; mono-winforms-list@lists.ximian.com
Subject: Re: [Mono-winforms-list] Double Buffering

Yeah, I had a look at it when you originally posted, but since I
couldn't
test at the time (working on richtext), it slipped my mind. Thanks for
the
reminder. I just committed a modified version, one that doesn't redraw
the
whole clientrectangle bitmap every time, but only the exposed area.
Thanks for catching this! I'm guessing you're using now double-buffering
in
PropertyGrid? Cool.

Cheers,
  Peter

-----Original Message-----
From: "Jonathan S. Chambers" <Jonathan.Chambers@ansys.com>
To: <mono-winforms-list@lists.ximian.com>
Date: 03 May, 2005 13:40
Subject: RE: [Mono-winforms-list] Double Buffering

Anyone take a look at this patch? I'm planning on checking in some
updates to the propertygrid, and this patch would cause redrawing of the
control to work correctly.

Thanks,
Jonathan

-----Original Message-----
From: mono-winforms-list-admin@lists.ximian.com
[mailto:mono-winforms-list-admin@lists.ximian.com] On Behalf Of Jonathan
S. Chambers
Sent: Thursday, April 28, 2005 8:52 PM
To: Jonathan S. Chambers; mono-winforms-list@lists.ximian.com
Subject: RE: [Mono-winforms-list] Double Buffering

Sorry about the message flurry. XplatUI.PaintEventEnd(Handle) wasn't
being called in quick repainting logic.

Thanks,
Jonathan

-----Original Message-----
From: mono-winforms-list-admin@lists.ximian.com on behalf of Jonathan
S. Chambers
Sent: Thu 4/28/2005 8:40 PM
To: Jonathan S. Chambers; mono-winforms-list@lists.ximian.com
Cc:
Subject: RE: [Mono-winforms-list] Double Buffering
The first patch is valid. The second is not. The logic looks like it
still needs fixed (when should needs_redraw be set to false), but my
solution does not seem to be working...

-----Original Message-----
From: mono-winforms-list-admin@lists.ximian.com on behalf of Jonathan
S. Chambers
Sent: Thu 4/28/2005 8:31 PM
To: Jonathan S. Chambers; mono-winforms-list@lists.ximian.com
Cc:
Subject: RE: [Mono-winforms-list] Double Buffering
Also, the setting of 'needs_redraw =3D false' (line 3181) should be =
moved
outside of the if block. Notice that it can never actually get inside
the if block, since that is the only place needs_redraw is set to false.

- Jonathan

-----Original Message-----
From: mono-winforms-list-admin@lists.ximian.com on behalf of Jonathan
S. Chambers
Sent: Thu 4/28/2005 8:21 PM
To: mono-winforms-list@lists.ximian.com
Cc:
Subject: [Mono-winforms-list] Double Buffering
      I noticed that support for double buffering has been included in
Control.cs. This is nice, except that I think the two calls to DrawImage
(lines 3177 and 3195) should pass ClientRectangle as the second
parameter, rather than ClipRectangle of the paint event args. According
to MS documentation, and actual behavior,  "The image represented by the
image object is scaled to the dimensions of the rect rectangle."
      Thus with the code as is, the code as is draws the ImageBuffer to
the ClipRectangle. When the clip rectangle is the entire control, this
makes sense. However, when the clip rectangle is just part of the
control (like when a partially obstructing window is removed) the whole
control is drawn to the clip area. (I can send an image if anyone wants
to see).

Thanks,
Jonathan

_______________________________________________
Mono-winforms-list maillist  -  Mono-winforms-list@lists.ximian.com
http://lists.ximian.com/mailman/listinfo/mono-winforms-list

_______________________________________________
Mono-winforms-list maillist  -  Mono-winforms-list@lists.ximian.com
http://lists.ximian.com/mailman/listinfo/mono-winforms-list