- Qt 5.15
- Qt Virtual Keyboard
- C++ Classes
- QVirtualKeyboardInputEngine
- Qt Virtual Keyboard | Commercial or GPLv3

# QVirtualKeyboardInputEngine Class

The InputEngine class provides an input engine that supports C++ and QML integration. More...

Header: | #include <QVirtualKeyboardInputEngine>
qmake: | QT += virtualkeyboard
Instantiated By: | InputEngine

- List of all members, including inherited members

## Public Types

enum class | InputMode { Latin, Numeric, Dialable, Pinyin, Cangjie, …, Thai }
enum class | PatternRecognitionMode { None, PatternRecognitionDisabled, Handwriting, HandwritingRecoginition }
enum class | ReselectFlag { WordBeforeCursor, WordAfterCursor, WordAtCursor }
flags | ReselectFlags
enum class | TextCase { Lower, Upper }

## Properties

- activeKey : const Qt::Key
- inputMethod : QVirtualKeyboardAbstractInputMethod*
- inputMode : InputMode
- inputModes : const QList<int>

- patternRecognitionModes : const QList<int>
- previousKey : const Qt::Key
- wordCandidateListModel : QVirtualKeyboardSelectionListModel* const
- wordCandidateListVisibleHint : const bool

## Public Functions

Qt::Key | activeKey() const
QVirtualKeyboardInputContext * | inputContext() const
QVirtualKeyboardAbstractInputMethod * | inputMethod() const
InputMode | inputMode() const
QList<int> | inputModes() const
QList<int> | patternRecognitionModes() const
Qt::Key | previousKey() const
bool | reselect(int cursorPosition, const ReselectFlags &reselectFlags)
void | setInputMethod(QVirtualKeyboardAbstractInputMethod *inputMethod)
void | setInputMode(InputMode inputMode)
QVirtualKeyboardTrace * | traceBegin(int traceId, PatternRecognitionMode patternRecognitionMode, const QVariantMap &traceCaptureDeviceInfo, const QVariantMap &traceScreenInfo)
bool | traceEnd(QVirtualKeyboardTrace *trace)
void | virtualKeyCancel()
bool | virtualKeyClick(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers)
bool | virtualKeyPress(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers, bool repeat)
bool | virtualKeyRelease(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers)
QVirtualKeyboardSelectionListModel * | wordCandidateListModel() const
bool | wordCandidateListVisibleHint() const

## Signals

void | activeKeyChanged(Qt::Key key)
void | inputMethodChanged()
void | inputMethodReset()
void | inputMethodUpdate()
void | inputModeChanged()
void | inputModesChanged()
void | patternRecognitionModesChanged()
void | previousKeyChanged(Qt::Key key)
void | virtualKeyClicked(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers, bool isAutoRepeat)
void | wordCandidateListModelChanged()
void | wordCandidateListVisibleHintChanged()

## Detailed Description

The input engine is responsible for routing input events to input methods. The actual input logic is implemented by the input methods.

The input engine also includes the default input method, which takes care of default processing if the active input method does not handle the event.

## Member Type Documentation

### enum class QVirtualKeyboardInputEngine::InputMode

This enum specifies the input mode for the input method.

Constant | Value | Description
--- | --- | ---
`QVirtualKeyboardInputEngine::InputMode::Latin` | `0` | The default input mode for latin text.
`QVirtualKeyboardInputEngine::InputMode::Numeric` | `1` | Only numeric input is allowed.
`QVirtualKeyboardInputEngine::InputMode::Dialable` | `2` | Only dialable input is allowed.
`QVirtualKeyboardInputEngine::InputMode::Pinyin` | `3` | Pinyin input mode for Chinese.
`QVirtualKeyboardInputEngine::InputMode::Cangjie` | `4` | Cangjie input mode for Chinese.
`QVirtualKeyboardInputEngine::InputMode::Zhuyin` | `5` | Zhuyin input mode for Chinese.
`QVirtualKeyboardInputEngine::InputMode::Hangul` | `6` | Hangul input mode for Korean.
`QVirtualKeyboardInputEngine::InputMode::Hiragana` | `7` | Hiragana input mode for Japanese.
`QVirtualKeyboardInputEngine::InputMode::Katakana` | `8` | Katakana input mode for Japanese.
`QVirtualKeyboardInputEngine::InputMode::FullwidthLatin` | `9` | Fullwidth latin input mode for East Asian languages.
`QVirtualKeyboardInputEngine::InputMode::Greek` | `10` | Greek input mode.
`QVirtualKeyboardInputEngine::InputMode::Cyrillic` | `11` | Cyrillic input mode.
`QVirtualKeyboardInputEngine::InputMode::Arabic` | `12` | Arabic input mode.
`QVirtualKeyboardInputEngine::InputMode::Hebrew` | `13` | Hebrew input mode.
`QVirtualKeyboardInputEngine::InputMode::ChineseHandwriting` | `14` | Chinese handwriting input mode.
`QVirtualKeyboardInputEngine::InputMode::JapaneseHandwriting` | `15` | Japanese handwriting input mode.
`QVirtualKeyboardInputEngine::InputMode::KoreanHandwriting` | `16` | Korean handwriting input mode.
`QVirtualKeyboardInputEngine::InputMode::Thai` | `17` | Thai input mode.

### enum class QVirtualKeyboardInputEngine::PatternRecognitionMode

This enum specifies the input mode for the input method.

Constant | Value | Description
--- | --- | ---
`QVirtualKeyboardInputEngine::PatternRecognitionMode::None` | `0` | Pattern recognition is not available.
`QVirtualKeyboardInputEngine::PatternRecognitionMode::PatternRecognitionDisabled` | `None` | `obsolete` Use PatternRecognitionMode::None
`QVirtualKeyboardInputEngine::PatternRecognitionMode::Handwriting` | `1` | Pattern recognition mode for handwriting recognition.
`QVirtualKeyboardInputEngine::PatternRecognitionMode::HandwritingRecoginition` | `Handwriting` | `obsolete` Use PatternRecognitionMode::Handwriting

### enum class QVirtualKeyboardInputEngine::ReselectFlag
flags QVirtualKeyboardInputEngine::ReselectFlags

This enum specifies the rules for word reselection.

Constant | Value | Description
--- | --- | ---
`QVirtualKeyboardInputEngine::ReselectFlag::WordBeforeCursor` | `0x1` | Activate the word before the cursor. When this flag is used exclusively, the word must end exactly at the cursor.
`QVirtualKeyboardInputEngine::ReselectFlag::WordAfterCursor` | `0x2` | Activate the word after the cursor. When this flag is used exclusively, the word must start exactly at the cursor.
`QVirtualKeyboardInputEngine::ReselectFlag::WordAtCursor` | `WordBeforeCursor | WordAfterCursor` | Activate the word at the cursor. This flag is a combination of the above flags with the exception that the word cannot start or stop at the cursor.

The ReselectFlags type is a typedef for QFlags<ReselectFlag>. It stores an OR combination of ReselectFlag values.

### enum class QVirtualKeyboardInputEngine::TextCase

This enum specifies the text case for the input method.

Constant | Value | Description
--- | --- | ---
`QVirtualKeyboardInputEngine::TextCase::Lower` | `0` | Lower case text.
`QVirtualKeyboardInputEngine::TextCase::Upper` | `1` | Upper case text.

## Property Documentation

### activeKey : const Qt::Key

This property holds the active key.

Currently pressed key.

Access functions:

Qt::Key | activeKey() const

Notifier signal:

void | activeKeyChanged(Qt::Key key)

### inputMethod : QVirtualKeyboardAbstractInputMethod*

This property holds the active input method.

Use this property to set active the input method, or to monitor when the active input method changes.

Access functions:

QVirtualKeyboardAbstractInputMethod * | inputMethod() const
void | setInputMethod(QVirtualKeyboardAbstractInputMethod *inputMethod)

Notifier signal:

void | inputMethodChanged()

### inputMode : InputMode

This property holds the current input mode.

Use this property to get or set the current input mode. The InputEngine::inputModes provides list of valid input modes for current input method and locale.

Access functions:

InputMode | inputMode() const
void | setInputMode(InputMode inputMode)

Notifier signal:

void | inputModeChanged()

### inputModes : const QList<int>

This property holds the available input modes for active input method.

The list of available input modes is dependent on the input method and locale. This property is updated when either of the dependencies changes.

Access functions:

QList<int> | inputModes() const

Notifier signal:

void | inputModesChanged()

### patternRecognitionModes : const QList<int>

This property holds the list of available pattern recognition modes.

The list of available pattern recognition modes.

This property was introduced in QtQuick.VirtualKeyboard 2.0.

Access functions:

QList<int> | patternRecognitionModes() const

Notifier signal:

void | patternRecognitionModesChanged()

### previousKey : const Qt::Key

This property holds the previous active key.

Previously pressed key.

Access functions:

Qt::Key | previousKey() const

Notifier signal:

void | previousKeyChanged(Qt::Key key)

### wordCandidateListModel : QVirtualKeyboardSelectionListModel* const

list model for the word candidate list.

Use this property to access the list model for the word candidate list.

Access functions:

QVirtualKeyboardSelectionListModel * | wordCandidateListModel() const

Notifier signal:

void | wordCandidateListModelChanged()

### wordCandidateListVisibleHint : const bool

visible hint for the word candidate list.

Use this property to check if the word candidate list should be visible in the UI.

Access functions:

bool | wordCandidateListVisibleHint() const

Notifier signal:

void | wordCandidateListVisibleHintChanged()

## Member Function Documentation

### `[signal]` void QVirtualKeyboardInputEngine::activeKeyChanged(Qt::Key key)

Indicates that the active key has changed.

Note: Notifier signal for property activeKey.

### `[signal]` void QVirtualKeyboardInputEngine::inputMethodChanged()

Indicates that the input method has changed.

Note: Notifier signal for property inputMethod.

### `[signal]` void QVirtualKeyboardInputEngine::inputMethodReset()

Emitted when the input method needs to be reset.

Note: This signal is automatically connected to QVirtualKeyboardAbstractInputMethod::reset() and InputMethod::reset() when the input method is activated.

### `[signal]` void QVirtualKeyboardInputEngine::inputMethodUpdate()

Note: This signal is automatically connected to QVirtualKeyboardAbstractInputMethod::update() and InputMethod::update() when the input method is activated.

### `[signal]` void QVirtualKeyboardInputEngine::inputModeChanged()

Indicates that the input mode has changed.

Note: Notifier signal for property inputMode.

### `[signal]` void QVirtualKeyboardInputEngine::inputModesChanged()

Indicates that the available input modes have changed.

Note: Notifier signal for property inputModes.

### `[signal]` void QVirtualKeyboardInputEngine::patternRecognitionModesChanged()

Indicates that the available pattern recognition modes have changed.

Note: Notifier signal for property patternRecognitionModes.

This function was introduced in QtQuick.VirtualKeyboard 2.0.

### `[signal]` void QVirtualKeyboardInputEngine::previousKeyChanged(Qt::Key key)

Indicates that the previous key has changed.

Note: Notifier signal for property previousKey.

### `[signal]` void QVirtualKeyboardInputEngine::virtualKeyClicked(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers, bool isAutoRepeat)

Indicates that the virtual key was clicked with the given text and modifiers. The isAutoRepeat indicates if the event is automatically repeated while the key is being pressed. This signal is emitted after the input method has processed the key event.

### Qt::Key QVirtualKeyboardInputEngine::activeKey() const

Returns the currently active key, or Qt::Key_unknown if no key is active.

Note: Getter function for property activeKey.

### QVirtualKeyboardInputContext *QVirtualKeyboardInputEngine::inputContext() const

Returns the `InputContext` instance associated with the input engine.

### QVirtualKeyboardAbstractInputMethod *QVirtualKeyboardInputEngine::inputMethod() const

Returns the active input method.

Note: Getter function for property inputMethod.

See also setInputMethod().

### QList<int> QVirtualKeyboardInputEngine::inputModes() const

Returns the list of available input modes.

Note: Getter function for property inputModes.

### QList<int> QVirtualKeyboardInputEngine::patternRecognitionModes() const

Returns list of supported pattern recognition modes.

Note: Getter function for property patternRecognitionModes.

### Qt::Key QVirtualKeyboardInputEngine::previousKey() const

Returns the previously active key, or Qt::Key_unknown if no key has been active.

Note: Getter function for property previousKey.

### bool QVirtualKeyboardInputEngine::reselect(int cursorPosition, const ReselectFlags &reselectFlags)

This function attempts to reselect a word located at the cursorPosition. The reselectFlags define the rules for how the word should be selected in relation to the cursor position.

The function returns `true` if the word was successfully reselected.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

This function was introduced in QtQuick.VirtualKeyboard 2.0.

### void QVirtualKeyboardInputEngine::setInputMethod(QVirtualKeyboardAbstractInputMethod *inputMethod)

Sets inputMethod as the active input method.

Note: Setter function for property inputMethod.

See also inputMethod().

### QVirtualKeyboardTrace *QVirtualKeyboardInputEngine::traceBegin(int traceId, PatternRecognitionMode patternRecognitionMode, const QVariantMap &traceCaptureDeviceInfo, const QVariantMap &traceScreenInfo)

Starts a trace interaction with the input engine.

The trace is uniquely identified by the traceId. The input engine will assign the id to the QVirtualKeyboardTrace object if the input method accepts the event.

The patternRecognitionMode specifies the recognition mode used for the pattern.

If the current input method accepts the event it returns a QVirtualKeyboardTrace object associated with this interaction. If the input method discards the event, it returns a NULL value.

The traceCaptureDeviceInfo provides information about the source device and the traceScreenInfo provides information about the screen context.

By definition, the QVirtualKeyboardTrace object remains valid until the traceEnd() method is called.

The trace interaction is ended by calling the traceEnd() method.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

This function was introduced in QtQuick.VirtualKeyboard 2.0.

### bool QVirtualKeyboardInputEngine::traceEnd(QVirtualKeyboardTrace *trace)

Ends the trace interaction with the input engine.

The trace object may be discarded at any point after calling this function.

The function returns true if the trace interaction was accepted (i.e. the touch events should not be used for anything else).

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

### void QVirtualKeyboardInputEngine::virtualKeyCancel()

Reverts the active key state without emitting the key event. This method is useful when the user discards the current key and the key state needs to be restored.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

### bool QVirtualKeyboardInputEngine::virtualKeyClick(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers)

Emits a key click event for the given key, text and modifiers. Returns `true` if the key event was accepted by the input engine.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

### bool QVirtualKeyboardInputEngine::virtualKeyPress(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers, bool repeat)

Called by the keyboard layer to indicate that key was pressed, with the given text and modifiers.

The key is set as an active key (down key). The actual key event is triggered when the key is released by the virtualKeyRelease() method. The key press event can be discarded by calling virtualKeyCancel().

The key press also initiates the key repeat timer if repeat is `true`.

Returns `true` if the key was accepted by this input engine.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.

See also virtualKeyCancel() and virtualKeyRelease().

### bool QVirtualKeyboardInputEngine::virtualKeyRelease(Qt::Key key, const QString &text, Qt::KeyboardModifiers modifiers)

Releases the key at key. The method emits a key event for the input method if the event has not been generated by a repeating timer. The text and modifiers are passed to the input method.

Returns `true` if the key was accepted by the input engine.

Note: This function can be invoked via the meta-object system and from QML. See Q_INVOKABLE.