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Diffstat (limited to 'doc/src/declarative/extending-tutorial.qdoc')
| -rw-r--r-- | doc/src/declarative/extending-tutorial.qdoc | 54 |
1 files changed, 28 insertions, 26 deletions
diff --git a/doc/src/declarative/extending-tutorial.qdoc b/doc/src/declarative/extending-tutorial.qdoc index 4caa631..0ddc430 100644 --- a/doc/src/declarative/extending-tutorial.qdoc +++ b/doc/src/declarative/extending-tutorial.qdoc @@ -27,13 +27,13 @@ /*! \page qml-extending-tutorial-index.html -\title Tutorial: Writing QML extensions with C++ +\title Tutorial: Writing QML Extensions with C++ The Qt Declarative module provides a set of APIs for extending QML through C++ extensions. You can write extensions to add your own QML types, extend existing Qt types, or call C/C++ functions that are not accessible from ordinary QML code. -This tutorial shows how to write a QML extension using C++ that includes +This tutorial shows how to write a QML extension using C++ that includes core QML features, including properties, signals and bindings. It also shows how extensions can be deployed through plugins. @@ -45,7 +45,7 @@ Tutorial chapters: \list 1 \o \l{declarative/tutorials/extending/chapter1-basics}{Creating a New Type} \o \l{declarative/tutorials/extending/chapter2-methods}{Connecting to C++ Methods and Signals} -\o \l{declarative/tutorials/extending/chapter3-bindings}{Adding Property Bindings} +\o \l{declarative/tutorials/extending/chapter3-bindings}{Property Binding} \o \l{declarative/tutorials/extending/chapter4-customPropertyTypes}{Using Custom Property Types} \o \l{declarative/tutorials/extending/chapter5-listproperties}{Using List Property Types} \o \l{declarative/tutorials/extending/chapter6-plugins}{Writing an Extension Plugin} @@ -67,18 +67,18 @@ like network programming that are not accessible through built-in QML features. In this tutorial, we will show how to use the C++ classes in the Qt Declarative module to extend QML. The end result will be a simple Pie Chart display implemented by -several custom QML types connected together through QML features like bindings and +several custom QML types connected together through QML features like bindings and signals, and made available to the QML runtime through a plugin. To begin with, let's create a new QML type called "PieChart" that has two properties: a name and a color. We will make it available in a \l {Modules}{module} called "Charts", with -a module version of 1.0. +a module version of 1.0. We want this \c PieChart type to be usable from QML like this: \code import Charts 1.0 - + PieChart { width: 100; height: 100 name: "A simple pie chart" @@ -99,16 +99,16 @@ Here is our \c PieChart class, defined in \c piechart.h: \snippet declarative/tutorials/extending/chapter1-basics/piechart.h 0 -The class inherits from QDeclarativeItem because we want to override +The class inherits from QDeclarativeItem because we want to override QDeclarativeItem::paint() in order to draw. If the class just represented some data type and was not an item that actually needed to be displayed, it could simply inherit -from QObject. Or, if we want to extend the functionality of an existing QObject-based +from QObject. Or, if we want to extend the functionality of an existing QObject-based class, it could inherit from that class instead. The \c PieChart class defines the two properties, \c name and \c color, with the Q_PROPERTY macro, -and overrides QDeclarativeItem::paint(). The class implementation in \c piechart.cpp -simply sets and returns the \c m_name and \c m_color values as appropriate, and -implements \c paint() to draw a simple pie chart. It also turns off the +and overrides QDeclarativeItem::paint(). The class implementation in \c piechart.cpp +simply sets and returns the \c m_name and \c m_color values as appropriate, and +implements \c paint() to draw a simple pie chart. It also turns off the QGraphicsItem::ItemHasNoContents flag to enable painting: \snippet declarative/tutorials/extending/chapter1-basics/piechart.cpp 0 @@ -150,19 +150,19 @@ Try it yourself with the code in Qt's \c examples/tutorials/extending/chapter1-b At the moment, the \c app.qml is run from within a C++ application. This may seem odd if you're used to running QML files with the \l {QML Viewer}. -Later on, we'll show how to create a plugin so that you can run \c app.qml using the +Later on, we'll show how to create a plugin so that you can run \c app.qml using the \l {QML Viewer} instead. */ /*! -\title Chapter 2: Connecting to C++ Methods and Signals +\title Chapter 2: Connecting to C++ Methods and Signals \example declarative/tutorials/extending/chapter2-methods Suppose we want \c PieChart to have a "clearChart()" method that erases the -chart and then emits a "chartCleared" signal. Our \c app.qml would be able +chart and then emits a "chartCleared" signal. Our \c app.qml would be able to call \c clearChart() and receive \c chartCleared() signals like this: \snippet declarative/tutorials/extending/chapter2-methods/app.qml 0 @@ -210,7 +210,7 @@ Property bindings is a powerful feature of QML that allows values of different elements to be synchronized automatically. It uses signals to notify and update other elements' values when property values are changed. -Let's enable property bindings for the \c color property. That means +Let's enable property bindings for the \c color property. That means if we have code like this: \snippet declarative/tutorials/extending/chapter3-bindings/app.qml 0 @@ -224,7 +224,7 @@ updates to the same value. When the window is clicked, the \c onClicked handler in the MouseArea changes the color of \c chartA, thereby changing both charts to the color blue. -It's easy to enable property binding for the \c color property. +It's easy to enable property binding for the \c color property. We add a \l{Qt's Property System}{NOTIFY} feature to its Q_PROPERTY() declaration to indicate that a "colorChanged" signal is emitted whenever the value changes. @@ -244,7 +244,7 @@ It's important for \c setColor() to check that the color value has actually chan before emitting \c colorChanged(). This ensures the signal is not emitted unnecessarily and also prevents loops when other elements respond to the value change. -The use of bindings is essential to QML. You should always add NOTIFY +The use of bindings is essential to QML. You should always add NOTIFY signals for properties if they are able to be implemented, so that your properties can be used in bindings. Properties that cannot be bound cannot be automatically updated and cannot be used as flexibly in QML. Also, since @@ -286,7 +286,7 @@ int-type property to store an identifier for each chart: \endcode We can also use various other property types. QML has built-in support for the types -listed in the \l{Adding Properties} documentation, which includes the following: +listed in the \l{QML Basic Types} documentation, which includes the following: \list \o bool, unsigned int, int, float, double, qreal @@ -299,7 +299,7 @@ listed in the \l{Adding Properties} documentation, which includes the following: If we want to create a property whose type is not supported by QML by default, we need to register the type with QML. -For example, let's replace the use of the \c property with a type called +For example, let's replace the use of the \c property with a type called "PieSlice" that has a \c color property. Instead of assigning a color, we assign an \c PieSlice value which itself contains a \c color: @@ -358,10 +358,10 @@ have a \c slices property that accepts a list of \c PieSlice items: \image extending-tutorial-chapter5.png To do this, we replace the \c pieSlice property in \c PieChart with a \c slices property, -declared as a QDeclarativeListProperty type. The QDeclarativeListProperty class enables the +declared as a QDeclarativeListProperty type. The QDeclarativeListProperty class enables the creation of list properties in QML extensions. We replace the \c pieSlice() -function with a \c slices() function that returns a list of slices, and add -an internal \c append_slice() function (discussed below). We also use a QList to +function with a \c slices() function that returns a list of slices, and add +an internal \c append_slice() function (discussed below). We also use a QList to store the internal list of slices as \c m_slices: \snippet declarative/tutorials/extending/chapter5-listproperties/piechart.h 0 @@ -409,7 +409,7 @@ To create a plugin library, we need: \list \o A plugin class that registers our QML types -\o A project file that describes the plugin +\o A project file that describes the plugin \o A \l{Writing a qmldir file}{qmldir} file that tells the QML engine to load the plugin \endlist @@ -468,8 +468,9 @@ In this tutorial, we've shown the basic steps for creating a QML extension: \endlist -The \l {Extending QML in C++} reference documentation shows other useful features that can be added to -QML extensions. For example, we could use \l{Default Property}{default properties} to allow +The \l {Extending QML Functionalities using C++} reference documentation shows +other useful features that can be added to QML extensions. For example, we +could use \l{Default Property}{default properties} to allow slices to be added without using the \c slices property: \code @@ -489,7 +490,8 @@ Or randomly add and remove slices from time to time using \l{Property Value Sour \endcode -See the \l{Extending QML in C++}{reference documentation} for more information. +See the \l{Extending QML Functionalities using C++} reference documentation +for more information. */ |