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diff --git a/doc/src/declarative/qmlsyntax.qdoc b/doc/src/declarative/qmlsyntax.qdoc new file mode 100644 index 0000000..fc25bce --- /dev/null +++ b/doc/src/declarative/qmlsyntax.qdoc @@ -0,0 +1,155 @@ +/**************************************************************************** +** +** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:FDL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Free Documentation License +** Alternatively, this file may be used under the terms of the GNU Free +** Documentation License version 1.3 as published by the Free Software +** Foundation and appearing in the file included in the packaging of this +** file. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! +\page qmlsyntax.html +\title QML Syntax +\ingroup QML Reference +\contentspage QML Reference + +\tableofcontents + +QML is a declarative language designed to describe the user interface of a +program: both what it looks like, and how it behaves. In QML, a user +interface is specified as a tree of objects with properties. + +JavaScript is used as a scripting language in QML, so you may want +to learn a bit more about it (\l{Javascript Guide}) before diving +deeper into QML. + +\section1 Basic QML Syntax + +QML looks like this: + +\code +import QtQuick 1.0 + +Rectangle { + width: 200 + height: 200 + color: "blue" + + Image { + source: "pics/logo.png" + anchors.centerIn: parent + } +} +\endcode + +Objects are specified by their type, followed by a pair of braces. Object +types always begin with a capital letter. In the above example, there are +two objects, a \l Rectangle, and an \l Image. Between the braces, we can specify +information about the object, such as its properties. + +Properties are specified as \c {propertyname: value}. In the above example, we +can see the Image has a property named \c source, which has been assigned the +value \c "pics/logo.png". The property and its value are separated by a colon. + +Properties can be specified one-per-line: + +\code +Rectangle { + width: 100 + height: 100 +} +\endcode + +or you can put multiple properties on a single line: + +\code +Rectangle { width: 100; height: 100 } +\endcode + +When multiple property/value pairs are specified on a single line, they +must be separated by a semicolon. + +The \c import statement imports the \c Qt \l{QML Modules}{module}, which contains all of the +standard \l {QML Elements}. Without this import statement, the \l Rectangle +and \l Image elements would not be available. + +\section1 Expressions + +In addition to assigning values to properties, you can also assign +expressions written in JavaScript. + +\code +Rotation { + angle: 360 * 3 +} +\endcode + +These expressions can include references to other objects and properties, in which case +a \e binding is established: when the value of the expression changes, the property the +expression has been assigned to is automatically updated to that value. + +\code +Item { + Text { + id: text1 + text: "Hello World" + } + Text { + id: text2 + text: text1.text + } +} +\endcode + +In the example above, the \c text2 object will display the same text as \c text1. If \c text1 is changed, +\c text2 is automatically changed to the same value. + +Note that to refer to other objects, we use their \e id values. (See below for more +information on the \e id property.) + +\section1 QML Comments + +Commenting in QML is similar to JavaScript. +\list +\o Single line comments start with // and finish at the end of the line. +\o Multiline comments start with /* and finish with *\/ +\endlist + +\snippet doc/src/snippets/declarative/comments.qml 0 + +Comments are ignored by the engine. They are useful for explaining what you +are doing; for referring back to at a later date, or for others reading +your QML files. + +Comments can also be used to prevent the execution of code, which is +sometimes useful for tracking down problems. + +\code +Text { + text: "Hello world!" + //opacity: 0.5 +} +\endcode + +In the above example, the Text object will have normal opacity, since the +line opacity: 0.5 has been turned into a comment. + +*/ |