QML Tutorial 1 - Basic Types

This first program is a very simple "Hello world" example that introduces some basic QML concepts. The picture below is a screenshot of this program.

Here is the QML code for the application:

import QtQuick 1.0
Rectangle {
    id: page
    width: 500; height: 200
    color: "lightgray"
    Text {
        id: helloText
        text: "Hello world!"
        y: 30
        anchors.horizontalCenter: page.horizontalCenter
        font.pointSize: 24; font.bold: true
    }
}

Walkthrough

Import

First, we need to import the types that we need for this example. Most QML files will import the built-in QML types (like Rectangle , Image , ...) that come with Qt, using:

import QtQuick 1.0

Rectangle element

Rectangle {
    id: page
    width: 500; height: 200
    color: "lightgray"

We declare a root element of type Rectangle . It is one of the basic building blocks you can use to create an application in QML. We give it an id to be able to refer to it later. In this case, we call it "page". We also set the width , height and color 特性。 Rectangle element contains many other properties (such as x and y ), but these are left at their default values.

Text element

    Text {
        id: helloText
        text: "Hello world!"
        y: 30
        anchors.horizontalCenter: page.horizontalCenter
        font.pointSize: 24; font.bold: true
    }

我们添加 Text element as a child of the root Rectangle element that displays the text 'Hello world!'.

The y property is used to position the text vertically at 30 pixels from the top of its parent.

The anchors.horizontalCenter property refers to the horizontal center of an element. In this case, we specify that our text element should be horizontally centered in the page 元素 (见 Anchor-Based Layout ).

The font.pointSize and font.bold properties are related to fonts and use the 点表示法 .

Viewing the example

To view what you have created, run the QML 查看器 tool (located in the bin directory) with your filename as the first argument. For example, to run the provided completed Tutorial 1 example from the install location, you would type:

bin/qmlviewer $QTDIR/examples/declarative/tutorials/helloworld/tutorial1.qml