Qt Quick Controls - Text Editor

The Text Editor Example presents a sample HTML file using the TextArea control, preserving the HTML formatting. The application comes with two user interfaces; one for traditional desktop platforms with a mouse pointer, and another simpler, touch-oriented version.

Desktop User Interface

The desktop version is a complete text editor with capabilities for formatting text, and opening and saving HTML and plain text files. It demonstrates the native-looking dialogs and menus using the Qt Labs Platform module. These types are mostly suitable for desktop platforms with support for multiple top-level windows, a mouse pointer, and moderate screen size.

The desktop UI uses FileDialog for opening and saving files:

     FileDialog {
         id: openDialog
         fileMode: FileDialog.OpenFile
         selectedNameFilter.index: 1
         nameFilters: ["Text files (*.txt)", "HTML files (*.html *.htm)", "Markdown files (*.md *.markdown)"]
         folder: StandardPaths.writableLocation(StandardPaths.DocumentsLocation)
         onAccepted: document.load(file)
     }

     FileDialog {
         id: saveDialog
         fileMode: FileDialog.SaveFile
         defaultSuffix: document.fileType
         nameFilters: openDialog.nameFilters
         selectedNameFilter.index: document.fileType === "txt" ? 0 : 1
         folder: StandardPaths.writableLocation(StandardPaths.DocumentsLocation)
         onAccepted: document.saveAs(file)
     }

It uses FontDialog and ColorDialog for choosing fonts and colors:

     FontDialog {
         id: fontDialog
         onAccepted: {
             document.fontFamily = font.family;
             document.fontSize = font.pointSize;
         }
     }

     ColorDialog {
         id: colorDialog
         currentColor: "black"
     }

It also uses Menu and MenuItem that provide a context menu to format text within:

     Menu {
         id: contextMenu

         MenuItem {
             text: qsTr("Copy")
             enabled: textArea.selectedText
             onTriggered: textArea.copy()
         }
         MenuItem {
             text: qsTr("Cut")
             enabled: textArea.selectedText
             onTriggered: textArea.cut()
         }
         MenuItem {
             text: qsTr("Paste")
             enabled: textArea.canPaste
             onTriggered: textArea.paste()
         }

         MenuSeparator {}

         MenuItem {
             text: qsTr("Font...")
             onTriggered: fontDialog.open()
         }

         MenuItem {
             text: qsTr("Color...")
             onTriggered: colorDialog.open()
         }
     }

Touch User Interface

The touch user interface is a simplified version of the text editor. It is suitable for touch devices with limited screen size. The example uses file selectors to load the appropriate user interface automatically.

Unlike the desktop version, which uses top-level dialogs, the touch version uses the QML Dialog type, which is not a top-level window. This type of dialog is fully supported on mobile and embedded platforms that do not support multiple top-level windows.

     Dialog {
         id: aboutDialog
         standardButtons: Dialog.Ok
         modal: true
         x: parent.width / 2 - width / 2
         y: parent.height / 2 - height / 2

         contentItem: Label {
             text: qsTr("Qt Quick Controls 2 - Text Editor Example")
         }
     }

C++ Backend

Both user interfaces use the same C++ backend, which supports opening, formatting, and editing a document. The C++ class, DocumentHandler, extends QObject and is registered as a QML type under the namespace io.qt.examples.texteditor 1.0.

The following snippets show how the type is registered under a namespace and later imported and instantiated by main.qml. For more information about registering C++ classes as QML types, see Defining QML Types from C++.

QML type registration:

 #include <QtQml/qqml.h>
 ...
 qmlRegisterType<DocumentHandler>("io.qt.examples.texteditor", 1, 0, "DocumentHandler");
 ...

QML namespace import:

 import io.qt.examples.texteditor 1.0

QML instance:

     DocumentHandler {
         id: document
         document: textArea.textDocument
         cursorPosition: textArea.cursorPosition
         selectionStart: textArea.selectionStart
         selectionEnd: textArea.selectionEnd
         textColor: colorDialog.color
         Component.onCompleted: {
             if (Qt.application.arguments.length === 2)
                 document.load("file:" + Qt.application.arguments[1]);
             else
                 document.load("qrc:/texteditor.html")
         }
         onLoaded: {
             textArea.textFormat = format
             textArea.text = text
         }
         onError: {
             errorDialog.text = message
             errorDialog.visible = true
         }
     }

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Example project @ code.qt.io