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Diffstat (limited to 'doc/src/declarative/qdeclarativedocument.qdoc')
-rw-r--r-- | doc/src/declarative/qdeclarativedocument.qdoc | 52 |
1 files changed, 25 insertions, 27 deletions
diff --git a/doc/src/declarative/qdeclarativedocument.qdoc b/doc/src/declarative/qdeclarativedocument.qdoc index b94e32e..423d77c 100644 --- a/doc/src/declarative/qdeclarativedocument.qdoc +++ b/doc/src/declarative/qdeclarativedocument.qdoc @@ -30,8 +30,6 @@ \title QML Documents \brief A description of QML documents and the kind of content they contain. -\section1 Introduction - A QML document is a block of QML source code. QML documents generally correspond to files stored on a disk or at a location on a network, but they can also be constructed directly from text data. @@ -42,17 +40,17 @@ Here is a simple QML document: QML documents are always encoded in UTF-8 format. -A QML document always begins with one or more import statements. To prevent elements -introduced in later versions from affecting existing QML programs, the element types -available within a document are controlled by the imported QML \l {Modules}. That is, +A QML document always begins with one or more import statements. To prevent elements +introduced in later versions from affecting existing QML programs, the element types +available within a document are controlled by the imported QML \l {Modules}. That is, QML is a \e versioned language. -Syntactically a QML document is self contained; QML does \e not have a preprocessor that -modifies the document prior to presentation to the QML runtime. \c import statements -do not "include" code in the document, but instead instruct the QML runtime on how to -resolve type references found in the document. Any type reference present in a QML -document - such as \c Rectangle and \c ListView - including those made within an -\l {Inline JavaScript}{JavaScript block} or \l {Property Binding}s, are \e resolved based exclusively on the +Syntactically a QML document is self contained; QML does \e not have a preprocessor that +modifies the document prior to presentation to the QML runtime. \c import statements +do not "include" code in the document, but instead instruct the QML runtime on how to +resolve type references found in the document. Any type reference present in a QML +document - such as \c Rectangle and \c ListView - including those made within an +\l {Inline JavaScript}{JavaScript block} or \l {Property Binding}s, are \e resolved based exclusively on the import statements. QML does not import any modules by default, so at least one \c import statement must be present or no elements will be available! @@ -63,12 +61,12 @@ resolved according to the document scope. \section1 Documents as Component Definitions -A QML document defines a single, top-level \l {QDeclarativeComponent}{QML component}. A QML component -is a template that is interpreted by the QML runtime to create an object with some predefined -behaviour. As it is a template, a single QML component can be "run" multiple times to -produce several objects, each of which are said to be \e instances of the component. +A QML document defines a single, top-level \l {QDeclarativeComponent}{QML component}. A QML component +is a template that is interpreted by the QML runtime to create an object with some predefined +behaviour. As it is a template, a single QML component can be "run" multiple times to +produce several objects, each of which are said to be \e instances of the component. -Once created, instances are not dependent on the component that created them, so they can +Once created, instances are not dependent on the component that created them, so they can operate on independent data. Here is an example of a simple "Button" component (defined in a \c Button.qml file) that is instantiated four times by \c application.qml. Each instance is created with a different value for its \c text property: @@ -80,7 +78,7 @@ Each instance is created with a different value for its \c text property: \row \o \snippet doc/src/snippets/declarative/qml-documents/qmldocuments.qml document -\o +\o \qml import QtQuick 1.0 @@ -112,23 +110,23 @@ to other QML components and applications in the same directory. \section1 Inline Components In addition to the top-level component that all QML documents define, and any reusable -components placed in separate files, documents may also -include \e inline components. Inline components are declared using the -\l Component element, as can be seen in the first example above. Inline components share +components placed in separate files, documents may also +include \e inline components. Inline components are declared using the +\l Component element, as can be seen in the first example above. Inline components share all the characteristics of regular top-level components and use the same \c import list as their -containing QML document. Components are one of the most basic building blocks in QML, and are +containing QML document. Components are one of the most basic building blocks in QML, and are frequently used as "factories" by other elements. For example, the \l ListView element uses the \c delegate component as the template for instantiating list items - each list item is just a new instance of the component with the item specific data set appropriately. -Like other \l {QML Elements}, the \l Component element is an object and must be assigned to a +Like other \l {QML Elements}, the \l Component element is an object and must be assigned to a property. \l Component objects may also have an object id. In the first example on this page, -the inline component is added to the \l Rectangle's \c resources list, and then -\l {Property Binding} is used to assign the \l Component to the \l ListView's \c delegate +the inline component is added to the \l Rectangle's \c resources list, and then +\l {Property Binding} is used to assign the \l Component to the \l ListView's \c delegate property. While using property binding allows the \l Component object to be shared (for example, -if the QML document contained multiple \l ListView's with the same delegate), in this case the -\l Component could have been assigned directly to the \l ListView's \c delegate. The QML -language even contains a syntactic optimization when assigning directly to a component property +if the QML document contained multiple \l ListView's with the same delegate), in this case the +\l Component could have been assigned directly to the \l ListView's \c delegate. The QML +language even contains a syntactic optimization when assigning directly to a component property for this case where it will automatically insert the \l Component tag. These final two examples are behaviorally identical to the original document. |