Re: Cocotron used for a real-world app

[Christopher Armstrong]

Hi all

I thought I'd add my two cents :-)

On 30/10/2008, at 3:51 AM, discuss-gnustep-request@gnu.org wrote:
> > > I agree that allowing for native-appearing GNUstep apps under  
> > > Windows is a
> > > great idea... but I don't think that's doable in the context of a  
> > > theme.
> > > Theming support is essential for GNUstep (obviously), but with  
> > > Windows, I
> > > think we need to really be using native widgets. There are just so  
> > > many ways
> > > that a Windows machine can be customized visually, that a theme  
> > > will almost
> > > always feel out of place (not to mention what we make that GNUstep  
> > > theme
> > > look like: XP or Vista or... something else). I have no idea how  
> > > this would
> > > be done technically, but it's most certainly the best way to give  
> > > the feel
> > > of a truly native application.

I thought this had already been technically proven - we don't need to  
use native widgets. Instead, Microsoft provide the uxtheme library,  
which lets us *paint* different parts of the native widgets through a  
difficulty but powerful API. I've already shown this is possible in my  
themeing patches a year or two ago (sorry, I've had no time to work on  
this further). You basically hook the GNUstep drawing using the  
GNUstep themeing, and draw the elements of a Windows control with  
uxtheme where we would draw a GNUstep control. This is exactly the way  
java SWING and GTK+ draw their widgets, and I'm guessing toolkits like  
wxWidgets and Qt do exactly the same. We don't need to create pixmaps  
out of the Windows controls (nor should we). It provides the ability  
to draw all the Windows controls. Microsoft provide it so that  
applications can pseudo-subclass the standard Windows Controls and add  
their own customisations to them.

The uxtheme API only exists on Windows XP and Vista, and it only works  
for the Royale/Bubble look on XP and Glass look on Vista. The  
traditional Windows look on XP/Vista, and Windows 2000 require us to  
"imitate" the old Windows look. However, when I was doing my work, I  
didn't know about the DrawFrameControl API you showed below - somehow  
I completely missed it. It would be able to draw the Windows 2000 look  
for buttons, panels etc that I was painting by hand.

The only problem is that we need to allow access to the HDC that the  
backend uses to draw at the theme level, which is a violation of the  
layering in gnustep-gui / gnustep-back. I think we can compromise on  
this point without much problem :-)

Regards
Chris

-----
Christopher Armstrong
carmstrong@fastmail.com.au