Wt

Hey Dan,

I think the following methods do what you are looking for:

  WWidget::setLayoutSizeAware()
  WWidget::layoutSizeChanged()

Regards,

koen

Ahhh! I missed that in the doco. I was expecting to find a signal that was emitted when the size changes. Since I am subclassing the WImage anyway, a virtual function will get the job done.

Thanks!

Dan

I'm having a little trouble with IE8 (Firefox, Chrome and Opera are all being well behaved).

I have the following simple case:

class MyImage : public Wt::WImage
{
 public:
    MyImage(const std::string &imageRef, Wt::WContainerWidget *parent=0) : Wt::WImage( imageRef, parent )
    {
        setLayoutSizeAware( true );
    }

    virtual void layoutSizeChanged( int w, int h )
    {
        std::cout << "*** The image size changed to: " << w << ", " << h << "\n";
    }
};

WApplication *app = new WApplication( appCspace_, env );

// use a VBox layout so that the app stretches to fill the window
Wt::WVBoxLayout *topLevelLayout = new Wt::WVBoxLayout(app->root());
topLevelLayout->setContentsMargins( 0, 0, 0, 0 );

// create my derived image that reports the size that it gets set to when laid out
Wt::WWidget* view = new MyImage( "http://www.google.com/images/logos/ps_logo2.png", app->root() );

// The resize( 100%, 100% ) was required to get the image to not maintain aspect ratio when resizing.
view->resize( Wt::WLength( 100.0, Wt::WLength::Percentage ), Wt::WLength( 100.0, Wt::WLength::Percentage ) );

topLevelLayout->addWidget( view, Wt::AlignTop | Wt::AlignLeft );

In IE8 there are two problems:

1. If you change the browser window height only, the image does not resize. Changing the width makes it honor the height of the browser window.
2. The image will not resize narrower than the actual image width - the browser clips the image instead and layoutSizeChanged() is not invoked.

I could live with (1) as a quirk, but (2) really stops me from being able to get the layout that I desire. Any suggestions? I'm using the git version of Wt.

Cheers,

Dan

Hey Dan,

(1) has been fixed in latest git.

for (2), you need to take the widget out of the CSS flow. I am starting to think that perhaps the layout managers could safely do this themselves, but until I have found an answer to that (by trial and error, as that is the start of the art of CSS :-) ), you can enable this for yourself using:

MyImage(const std::string &imageRef, Wt::WContainerWidget *parent=0) : Wt::WImage( imageRef, parent )
{
  setPositionScheme(Absolute);
  setLayoutSizeAware( true );
}

Hi Koen,

Calling setPositionScheme(Absolute) has fixed the IE8. I don't envy you trying to get this to work consistently across all the browsers!

Thanks,

Dan