AutoScroller.qml Example File

basic/content/AutoScroller.qml
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 ** Contact: https://www.qt.io/licensing/
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 ** This file is part of the Qt Virtual Keyboard module of the Qt Toolkit.
 **
 ** $QT_BEGIN_LICENSE:GPL$
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 ** GNU General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU
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 ** the Free Software Foundation and appearing in the file LICENSE.GPL3
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 import QtQuick 2.0
 import QtQuick.VirtualKeyboard 2.1

 Item {

     property var innerFlickable
     property var outerFlickable
     property var inputItem: InputContext.priv.inputItem

     onInputItemChanged: {
         innerFlickable = null
         outerFlickable = null
         if (inputItem !== null) {
             var parent_ = inputItem.parent
             while (parent_) {
                 if (parent_.maximumFlickVelocity) {
                     if (innerFlickable) {
                         outerFlickable = parent_
                         break
                     } else {
                         innerFlickable = parent_
                     }
                 }
                 parent_ = parent_.parent
             }
             delayedLoading.restart()
         }
     }

     function ensureVisible(flickable) {
         if (Qt.inputMethod.visible && inputItem && flickable && flickable.visible && flickable.interactive) {

             var verticallyFlickable = (flickable.flickableDirection === Flickable.HorizontalAndVerticalFlick || flickable.flickableDirection === Flickable.VerticalFlick
                                        || (flickable.flickableDirection === Flickable.AutoFlickDirection && flickable.contentHeight > flickable.height))
             var horizontallyFlickable = (flickable.flickableDirection === Flickable.HorizontalAndVerticalFlick || flickable.flickableDirection === Flickable.HorizontalFlick
                                          || (flickable.flickableDirection === Flickable.AutoFlickDirection && flickable.contentWidth > flickable.width))

             if ((!verticallyFlickable && !horizontallyFlickable) || !inputItem.hasOwnProperty("cursorRectangle"))
                 return

             var cursorRectangle = flickable.contentItem.mapFromItem(inputItem, inputItem.cursorRectangle.x, inputItem.cursorRectangle.y)

             var oldContentY = flickable.contentY
             if (verticallyFlickable) {
                 var scrollMarginVertical = (flickable && flickable.scrollMarginVertical) ? flickable.scrollMarginVertical : 10
                 if (flickable.contentY >= cursorRectangle.y  - scrollMarginVertical)
                     flickable.contentY = Math.max(0, cursorRectangle.y  - scrollMarginVertical)
                 else if (flickable.contentY + flickable.height <= cursorRectangle.y  + inputItem.cursorRectangle.height + scrollMarginVertical)
                     flickable.contentY = Math.min(flickable.contentHeight - flickable.height, cursorRectangle.y + inputItem.cursorRectangle.height - flickable.height + scrollMarginVertical)
             }
             if (horizontallyFlickable) {
                 var scrollMarginHorizontal = (flickable && flickable.scrollMarginHorizontal) ? flickable.scrollMarginHorizontal : 10
                 if (flickable.contentX >= cursorRectangle.x - scrollMarginHorizontal)
                     flickable.contentX = Math.max(0, cursorRectangle.x - scrollMarginHorizontal)
                 else if (flickable.contentX + flickable.width <= cursorRectangle.x + inputItem.cursorRectangle.width + scrollMarginHorizontal)
                     flickable.contentX = Math.min(flickable.contentWidth - flickable.width, cursorRectangle.x + inputItem.cursorRectangle.width - flickable.width + scrollMarginHorizontal)
             }
         }
     }
     Timer {
         id: delayedLoading
         interval: 10
         onTriggered: {
             ensureVisible(innerFlickable)
             ensureVisible(outerFlickable)
         }
     }
     Connections {
         ignoreUnknownSignals: true
         target: Qt.inputMethod
         onAnimatingChanged: if (inputItem && !Qt.inputMethod.animating) delayedLoading.restart()
         onKeyboardRectangleChanged: if (inputItem) delayedLoading.restart()
         onCursorRectangleChanged: if (inputItem && inputItem.activeFocus) delayedLoading.restart()
     }
 }