Re: [boost] Java style GUI in C++

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2004-08-18 14:11:36

John Torjo wrote:
>Hi Reece,
>
>Just a few thoughts:
>
>>I am currently designing a GUI framework in C++ (initially targeting the 
>>Windows platform) that uses a model similar to that which Java uses in
>
>Take a deep breath if you want to make it cross-platform ;)
>I think that's Windows work x 10 or so. Maybe more ;) ...

I was thinking about having a compatibility layer, e.g.:

namespace windows
{
   class window
   {
      public:
         inline handle_type create( const string_type title, ... );
         inline void set_size( long, long );
         // ...
   };
}

namespace linux{ class window{ ... }; }

Then engineer the library on top of that. This would simplify x-platform 
development... the problem is working out the right abstraction.

>>it's AWT and Swing libraries. Specifically:
>>
>>[1] Being able to use constructors to create the windows/components. This 
>>means there is no need to explicitly call a Create method like in the MFC 
>>framework.
>
>win32gui does that ;)

:) I am having a look at all the links to the various libraries, so it may 
take a while to process them all. (Thanks for everyone who compiled the 
links).

>>[2] The use of layout managers. I like the various layout managers in Java 
>>and how easy it is to construct complex GUI interfaces.
>
>I like the idea of layout managers. Still, it seems (to me) in real-life 
>they kind of fail. You'll always want that special case where you need to 
>hide control X and show control Y, etc.

So why not have that ability in the framework? That is the reason I posted 
this, to get ideas. It should not be that difficult to be able to change the 
layouts at run-time... once the layout managers have been written, that is.

>So far, I've created splitters on dialogs at design time (still beta ;)). 
>If you use them correctly, you can specify a lot ot design time. Also, you 
>can easily hide/show the left/right panes.

cool.

>>[3] The support for events via "listeners". This will most likely be 
>>geared towards key/mouse events and "action" events (e.g. when the user 
>>presses on a button).
>
>I'm not a big fan of listeners. You need to do a lot of coding manually to 
>set them, etc. I've implemented them totally different - using event 
>handler classes.

My idea was something along the lines of:

class MouseEvent
{
   public:
      static const int                 LeftButton   = 0;
      static const int                 MiddleButton = 1;
      static const int                 RightButton  = 2;
   private:
      int                              button;
      unsigned int                     vkeys;
      win::api::point                  pt;
   public:
      inline                 MouseEvent( int, WPARAM, LPARAM );
};

MouseEvent::MouseEvent( int btn, WPARAM wp, LPARAM lp ):
   button( btn ),
   vkey(   wp ),
   pt(     lp )
{
}

class MouseListener
{
   public:
      virtual void                               mouseMove(              
const MouseEvent & );
      virtual void                               mouseButtonDown(        
const MouseEvent & );
      virtual void                               mouseButtonUp(          
const MouseEvent & );
      virtual void                               mouseButtonDoubleClick( 
const MouseEvent & );
   public:
      virtual               ~MouseButtonListener();
};

With a common listener interface for GUI object actions, e.g. pressing a 
mouse button, selecting an item in a listbox, editing text, etc.

>>At the moment, I have a basic working version that allows you to write the 
>>following:
>>
>>int PASCAL WinMain( HINSTANCE, HINSTANCE, LPSTR, int sw )
>>{
>>   swing::JFrame frame( L"Swing JFrame!" );
>>   frame.setPane( new swing::JPanel());
>>   frame.setSize( 500, 500 );
>>   frame.show( sw );
>>
>>   MessageLoop msg;
>>   return( msg.Execute());
>>}
>
>can you break the message loop?
>That is, specify when a message loop should end (when a certain signal is 
>received).

You can call ::PostQuitMessage( 0 ), but that is Windows specific. At the 
moment the message loop doesn't do anything fancy (accelerator/dialog box 
message processing), but it is on the list of things to work on.

>>This creates two windows: the main frame and a panel that is a child of 
>>that frame. The JFrame is created in the constructor, but is not displayed 
>>until show is called. Likewise, the JPanel is created inside its 
>>constructor and the JFrame.setPane method makes that window a child of the 
>>frame.
>>
>>I would appreciate comments and ideas as to what people would like out of 
>>a GUI framework, especially one that will be multi-platform.
>
>I'm all for it, but again, I think it's so much work...

But it will be fun! :D

Regards,
Reece

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