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/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
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** No Commercial Usage
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** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
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** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\page anchor-layout.html
\target anchor-layout
\title Anchor-based Layout in QML
In addition to the more traditional \l Grid, \l Row, and \l Column,
QML also provides a way to layout items using the concept of \e anchors.
Each item can be thought of as having a set of 7 invisible "anchor lines":
\e left, \e horizontalCenter, \e right, \e top, \e verticalCenter, \e baseline, and \e bottom.
\image edges_qml.png
The baseline (not pictured above) corresponds to the imaginary line on which
text would sit. For items with no text it is the same as \e top.
The QML anchoring system allows you to define relationships between the anchor lines of different items. For example, you can write:
\code
Rectangle { id: rect1; ... }
Rectangle { id: rect2; anchors.left: rect1.right; ... }
\endcode
In this case, the left edge of \e rect2 is bound to the right edge of \e rect1, producing the following:
\image edge1.png
The anchoring system also allows you to specify margins and offsets. Margins specify the amount of empty space to leave to the outside of an item, while offsets allow you to manipulate positioning using the center anchor lines. Note that margins specified using the anchor layout system only have meaning for anchors; they won't have any effect when using other layouts or absolute positioning.
\image margins_qml.png
The following example specifies a left margin:
\code
Rectangle { id: rect1; ... }
Rectangle { id: rect2; anchors.left: rect1.right; anchors.leftMargin: 5; ... }
\endcode
In this case, a margin of 5 pixels is reserved to the left of \e rect2, producing the following:
\image edge2.png
You can specify multiple anchors. For example:
\code
Rectangle { id: rect1; ... }
Rectangle { id: rect2; anchors.left: rect1.right; anchors.top: rect1.bottom; ... }
\endcode
\image edge3.png
By specifying multiple horizontal or vertical anchors you can control the size of an item. For example:
\code
Rectangle { id: rect1; x: 0; ... }
Rectangle { id: rect2; anchors.left: rect1.right; anchors.right: rect3.left; ... }
Rectangle { id: rect3; x: 150; ... }
\endcode
\image edge4.png
\section1 Limitations
For performance reasons, you can only anchor an item to its siblings and direct parent. For example, the following anchor would be considered invalid and would produce a warning:
\badcode
Item {
id: group1
Rectangle { id: rect1; ... }
}
Item {
id: group2
Rectangle { id: rect2; anchors.left: rect1.right; ... } // invalid anchor!
}
\endcode
*/
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