[Rock-dev] Subclassing a C++ widget from ruby, and registering the result as a Vizkit widget

[Alexander Duda]

On Mon, 2011-04-11 at 11:09 +0200, Sylvain Joyeux wrote:
> Hello
> 
> I'd like to subclass the ImageView widget to create a RasterMapView 
> widget -- which is basically converting a Gdal raster band into an image.
> 
> I'd like to do it in Ruby ... and register the result in vizkit.
> 
> As far as I understood, it boils down to get vizkit to return me the 
> ImageView class (NOT an ImageView instance), i.e.
> 
> 
> <code>
> require 'vizkit'
> image_view_klass = Vizkit.<I don't know what to put there>
> class RasterMapView < image_view_klass
>    [implement the view]
> end
> Vizkit::UILoader.register_ruby_widget "RasterMapView", 
> RasterMapView.method(:new)
> Vizkit::UILoader.register_widget_for "RasterMapView", Gdal::Band, :display
> </code>
> 
> Can I do that ? And if I can, how ?
> 
> Sylvain

This is not going to work because the ImageView class is not known to
ruby. You can only instantiate an instance of the ImageView class which
behaves like a QWidget class on the ruby side.

Unfortunately all events from the ImageView class are not redirected to
the ruby instance so you cannot extend the instance to implement a new
behavior. To get this running you have to write qt bindings.

But you could create your own view by creating a custom QImage which is
displayed by a ImageView instance. 

Alex

-- 
Dipl.-Ing. Alexander Duda 
Unterwasserrobotik

DFKI Bremen
Robotics Innovation Center
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E-Mail: alexander.duda at dfki.de

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