title: How to set an initial size of a QScrollArea?
body: <p>I know that this is a very specific C++ and Qt related question, but maybe someone can help me, anyway ...</p>
  
  <p>See the code below: I want to display an image within a scroll area. The view port of the scroll area shall have a defined initial size. That means, if the image's size is bigger than the initial size of the view port, scroll bars will be visible, otherwise not.</p>
  
  <pre><code>// create label for displaying an image
  QImage image( ":/test.png" );
  QLabel *label = new QLabel( this );
  label-&gt;setPixmap( image.toPixmap() );
  
  // put label into scroll area
  QScollArea *area = new QScrollArea( this );
  area-&gt;setWidget( label );
  
  // set the initial size of the view port
  // NOTE: This is what I'd like to do, but this method does not exist :(
  area-&gt;setViewPortSize( QSize( 300, 300 ) );
  </code></pre>
  
  <p>It shall be possible to resize the whole application so that the view port will get another size than the initial one.</p>
  
  <p>Unfortunatelly I was not able to find out, how to set the size of the view port. Qt's layout mechanism seems to set a default size for the view port, but up to now I was not able to change it. Setting a new size with </p>
  
  <pre><code>area-&gt;setMinimumSize( QSize( 300, 300 ) );
  </code></pre>
  
  <p>will actually set the demanded size, but then the scroll area looses the ability to get resized to a size smaller than 300x300.</p>
  
  <p>Any ideas?</p>