com.trolltech.qt.gui
Interface QLayoutItemInterface

All Superinterfaces:
QtJambiInterface
All Known Implementing Classes:
QBoxLayout, QFormLayout, QGridLayout, QHBoxLayout, QLayout, QLayoutItem, QSpacerItem, QStackedLayout, QVBoxLayout, QWidgetItem

public interface QLayoutItemInterface
extends QtJambiInterface

The QLayoutItem class provides an abstract item that a QLayout manipulates. This is used by custom layouts.

Pure virtual functions are provided to return information about the layout, including, sizeHint(), minimumSize(), maximumSize() and expanding().

The layout's geometry can be set and retrieved with setGeometry() and geometry(), and its alignment with setAlignment() and alignment().

isEmpty() returns whether the layout item is empty. If the concrete item is a QWidget, it can be retrieved using widget(). Similarly for layout() and spacerItem().

Some layouts have width and height interdependencies. These can be expressed using hasHeightForWidth(), heightForWidth(), and minimumHeightForWidth(). For more explanation see the Qt Quarterly article Trading Height for Width.

See also:
QLayout.


Method Summary
 Qt.Alignment alignment()
          Returns the alignment of this item.
 QSizePolicy.ControlTypes controlTypes()
          Returns the control type(s) for the layout item.
 Qt.Orientations expandingDirections()
          Returns whether this layout item can make use of more space than sizeHint().
 QRect geometry()
          Returns the rectangle covered by this layout item.
 boolean hasHeightForWidth()
          Returns true if this layout's preferred height depends on its width; otherwise returns false.
 int heightForWidth(int arg__1)
          Returns the preferred height for this layout item, given the width w.
 void invalidate()
          Invalidates any cached information in this layout item.
 boolean isEmpty()
           
 QLayout layout()
          If this item is a QLayout, it is returned as a QLayout; otherwise 0 is returned.
 QSize maximumSize()
          Implemented in subclasses to return the maximum size of this item.
 int minimumHeightForWidth(int arg__1)
          Returns the minimum height this widget needs for the given width, w.
 QSize minimumSize()
          Implemented in subclasses to return the minimum size of this item.
 void setAlignment(Qt.Alignment a)
          Sets the alignment of this item to alignment.
 void setGeometry(QRect arg__1)
           
 QSize sizeHint()
          Implemented in subclasses to return the preferred size of this item.
 QSpacerItem spacerItem()
          If this item is a QSpacerItem, it is returned as a QSpacerItem; otherwise 0 is returned.
 QWidget widget()
          If this item is a QWidget, it is returned as a QWidget; otherwise 0 is returned.
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Method Detail

alignment

Qt.Alignment alignment()
Returns the alignment of this item.

See also:
setAlignment().


controlTypes

QSizePolicy.ControlTypes controlTypes()
Returns the control type(s) for the layout item. For a QWidgetItem, the control type comes from the widget's size policy; for a QLayoutItem, the control types is derived from the layout's contents.

See also:
QSizePolicy::controlType().


setAlignment

void setAlignment(Qt.Alignment a)
Sets the alignment of this item to alignment.

Note: Item alignment is only supported by QLayoutItem subclasses where it would have a visual effect. Except for QSpacerItem, which provides blank space for layouts, all public Qt classes that inherit QLayoutItem support item alignment.

See also:
alignment().


expandingDirections

Qt.Orientations expandingDirections()
Returns whether this layout item can make use of more space than sizeHint(). A value of Qt::Vertical or Qt::Horizontal means that it wants to grow in only one dimension, whereas Qt::Vertical | Qt::Horizontal means that it wants to grow in both dimensions.


geometry

QRect geometry()
Returns the rectangle covered by this layout item.

See also:
setGeometry().


hasHeightForWidth

boolean hasHeightForWidth()
Returns true if this layout's preferred height depends on its width; otherwise returns false. The default implementation returns false.

Reimplement this function in layout managers that support height for width.

See also:
heightForWidth(), and QWidget::heightForWidth().


heightForWidth

int heightForWidth(int arg__1)
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:

    public int heightForWidth(int w)
    {
        if (cache_dirty || cached_width != w) {
            int h = calculateHeightForWidth(w);
            cached_hfw = h;
            return h;
        }
        return cached_hfw;
    }
Caching is strongly recommended; without it layout will take exponential time.

See also:
hasHeightForWidth().


invalidate

void invalidate()
Invalidates any cached information in this layout item.


isEmpty

boolean isEmpty()

layout

QLayout layout()
If this item is a QLayout, it is returned as a QLayout; otherwise 0 is returned. This function provides type-safe casting.


maximumSize

QSize maximumSize()
Implemented in subclasses to return the maximum size of this item.


minimumHeightForWidth

int minimumHeightForWidth(int arg__1)
Returns the minimum height this widget needs for the given width, w. The default implementation simply returns heightForWidth(w).


minimumSize

QSize minimumSize()
Implemented in subclasses to return the minimum size of this item.


setGeometry

void setGeometry(QRect arg__1)

sizeHint

QSize sizeHint()
Implemented in subclasses to return the preferred size of this item.


spacerItem

QSpacerItem spacerItem()
If this item is a QSpacerItem, it is returned as a QSpacerItem; otherwise 0 is returned. This function provides type-safe casting.


widget

QWidget widget()
If this item is a QWidget, it is returned as a QWidget; otherwise 0 is returned. This function provides type-safe casting.