// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

import QtQuick
// Deliberately imported after QtQuick to avoid missing restoreMode property in Binding. Fix in Qt 6.
import QtQml
import QtQuick.Window
import QtQuick.VirtualKeyboard
import QtQuick.VirtualKeyboard.Components

/*!
    \qmltype HandwritingInputPanel
    \inqmlmodule QtQuick.VirtualKeyboard
    \since QtQuick.VirtualKeyboard 2.0

    \brief Provides a handwriting panel add-on for the virtual keyboard UI.
    \ingroup qmlclass
    \ingroup qtvirtualkeyboard-qml

    The HandwritingInputPanel is an add-on component for the InputPanel, which
    enables full-screen handwriting input for the application.

    HandwritingInputPanel is designed to be anchored full screen alongside
    the InputPanel. The operating principle is that when the handwriting panel
    is "available", the InputPanel is invisible. This functionality is built-in,
    and requires no more than a reference to the InputPanel instance.

    The panel is set into operation by setting the \l {HandwritingInputPanel::}{available}
    property to \c true. When the panel is in operation, the keyboard remains hidden
    when the input focus is set. When \c available is \c true, handwriting input is
    activated by setting the \l {HandwritingInputPanel::}{active} property to \c true.

    The user interface, which provides controls for handwriting mode and the
    visibility of the keyboard, is application-specific. One suggested implementation
    is to use a floating button on the handwriting panel, where single click toggles
    the handwriting mode (changes the \l {HandwritingInputPanel::}{active} property), and double-click toggles
    the visibility of the keyboard (changes the \l {HandwritingInputPanel::}{available} property).

    HandwritingInputPanel also provides a word candidate popup which allows the user
    to select an alternative word candidate from the list of suggestions generated
    by the handwriting input method.
*/

Item {
    id: handwritingInputPanel

    /*! A reference to the input panel instance.

        This property must be set to the existing input panel instance.
    */
    property var inputPanel

    /*! This property controls the availability status of the handwriting input method.

        Setting the property to \c true prepares the handwriting input method and inhibits
        the display of keyboard.
    */
    property bool available

    /*! This property controls the active status of the handwriting input method.

        Setting the property to \c true activates the handwriting input method. When the
        handwriting input method is active, all touch input is captured by the
        handwriting input panel and redirected to input engine for processing.
    */
    property bool active

    state: enabled && available ? (active ? "active" : "available") : "unavailable"
    enabled: inputPanel.keyboard.isHandwritingAvailable()
    visible: enabled && available && active && Qt.inputMethod.visible

    LayoutMirroring.enabled: false
    LayoutMirroring.childrenInherit: true

    Item {
        id: keyboard
        property var style: inputPanel && inputPanel.hasOwnProperty ? inputPanel.keyboard.style : null
        property var soundEffect: inputPanel && inputPanel.hasOwnProperty ? inputPanel.keyboard.soundEffect : null
    }

    onEnabledChanged: inputPanel.keyboard.fullScreenHandwritingMode = enabled && available
    onAvailableChanged: inputPanel.keyboard.fullScreenHandwritingMode = enabled && available

    TraceInputArea {
        id: hwrInputArea
        enabled: handwritingInputPanel.enabled && handwritingInputPanel.available && handwritingInputPanel.active
        objectName: "hwrInputArea"
        anchors.fill: parent
        patternRecognitionMode: InputEngine.PatternRecognitionMode.Handwriting
        canvasType: "fullscreen"
    }

    Binding {
        target: InputContext.priv
        property: "keyboardRectangle"
        value: Qt.rect(hwrInputArea.x, hwrInputArea.y, hwrInputArea.width, hwrInputArea.height)
        when: handwritingInputPanel.enabled && handwritingInputPanel.available && handwritingInputPanel.active
    }

    Binding {
        target: inputPanel ? inputPanel.keyboard : null
        property: "active"
        value: false
        when: handwritingInputPanel.enabled && handwritingInputPanel.available
        restoreMode: Binding.RestoreBinding
    }

    WordCandidatePopupList {
        id: wordCandidatePopupList
        z: 1
        objectName: "wordCandidatePopupList"
        enabled: handwritingInputPanel.enabled && handwritingInputPanel.available && handwritingInputPanel.active
    }

    Loader {
        sourceComponent: keyboard.style.popupListBackground
        anchors.fill: wordCandidatePopupList
        z: -1
        visible: wordCandidatePopupList.visible
    }
}
