QLayoutItem Class Reference
[QtGui module]

int QLayoutItem::heightForWidth ( int w ) const   [virtual]

Returns the preferred height for this layout item, given the width w.

The default implementation returns -1, indicating that the preferred height is independent of the width of the item. Using the function hasHeightForWidth() will typically be much faster than calling this function and testing for -1.

Reimplement this function in layout managers that support height for width. A typical implementation will look like this:

 int MyLayout::heightForWidth(int w) const
 {
     if (cache_dirty || cached_width != w) {
         // not all C++ compilers support "mutable"
         MyLayout *that = (MyLayout*)this;
         int h = calculateHeightForWidth(w);
         that->cached_hfw = h;
         return h;
     }
     return cached_hfw;
 }

Caching is strongly recommended; without it layout will take exponential time.

See also hasHeightForWidth().