Android backbutton

erik.ridderby

I managed to catch the android back button in QML:

@ApplicationWindow {
onClosing: {
close.accepted = false
if (contextMenuManager.menuVisible)
contextMenuManager.menuVisible = false
}
}@

Rizzer

Keys.onReleased catches the Android back button in some instances.

It doesn't seem to work with ListView though. focus must be directed somewhere where I haven't anticipated.

Here is a sample main.qml with a ListView, which does not catch the Android back button:
@
import QtQuick 2.3
import QtQuick.Controls 1.2
import QtQuick.Layouts 1.1

ApplicationWindow {
id: appWindow
visible: true
width: 640
height: 480
title: qsTr("Hello World")

ListModel {
    id: longModel

    Component.onCompleted: {
        for ( var i=1; i<=100; i++ )
            append({"testName": i})
    }
}


ListView {
    anchors.fill: parent
    id: listView
    model: longModel

    delegate:
        Rectangle {
            height: 80
        width: parent.width

        Text {
            id: textComponent
            text: testName
        }
        Keys.onReleased: {
            if (event.matches(StandardKey.Back)) {
                console.log("back caught by delegate");
                event.accepted = true;
            }
        }
    }

    focus: true
    Keys.onReleased: {
        if (event.matches(StandardKey.Back)) {
            console.log("back caught by listview");
            event.accepted = true;
        }
    }

}

}
@

Rizzer

Keys.onReleased catches the Android back button in some instances.

It doesn't seem to work with ListView though. focus must be directed somewhere where I haven't anticipated.

Here is a sample main.qml with a ListView, which does not catch the Android back button:
@
import QtQuick 2.3
import QtQuick.Controls 1.2
import QtQuick.Layouts 1.1

ApplicationWindow {
id: appWindow
visible: true
width: 640
height: 480
title: qsTr("Hello World")

ListModel {
    id: longModel

    Component.onCompleted: {
        for ( var i=1; i<=100; i++ )
            append({"testName": i})
    }
}


ListView {
    anchors.fill: parent
    id: listView
    model: longModel

    delegate:
        Rectangle {
            height: 80
        width: parent.width

        Text {
            id: textComponent
            text: testName
        }
        Keys.onReleased: {
            if (event.matches(StandardKey.Back)) {
                console.log("back caught by delegate");
                event.accepted = true;
            }
        }
    }

    focus: true
    Keys.onReleased: {
        if (event.matches(StandardKey.Back)) {
            console.log("back caught by listview");
            event.accepted = true;
        }
    }

}

}
@

Mr_Ada

Can someone post a C++ version of this? I have tried to convert it and I am still not seeing the back key.

Never mind.... Here is a C++ version I was able to get to work....

@
#include <QDebug>

// regular MainWindow stuff...

void MainWindow::keyPressEvent (QKeyEvent* event) {

if (event->key () == Qt::Key_Back)
qDebug () << "<<keyPressEvent>> " <<
"[[Back button]]";
else if (event->key () == Qt::Key_HomePage)
qDebug () << "<<keyPressEvent>> " <<
"[[Home button]]";
else if (event->key () == Qt::Key_Menu)
qDebug () << "<<keyPressEvent>> " <<
"[[Menu button]]";
else if (event->key () == Qt::Key_unknown)
qDebug () << "<<keyPressEvent>> " <<
"[[Unknown button]]";
event->accept ();
}
@

Mr_Ada

Can someone post a C++ version of this? I have tried to convert it and I am still not seeing the back key.

Never mind.... Here is a C++ version I was able to get to work....

@
#include <QDebug>

// regular MainWindow stuff...

void MainWindow::keyPressEvent (QKeyEvent* event) {

if (event->key () == Qt::Key_Back)
qDebug () << "<<keyPressEvent>> " <<
"[[Back button]]";
else if (event->key () == Qt::Key_HomePage)
qDebug () << "<<keyPressEvent>> " <<
"[[Home button]]";
else if (event->key () == Qt::Key_Menu)
qDebug () << "<<keyPressEvent>> " <<
"[[Menu button]]";
else if (event->key () == Qt::Key_unknown)
qDebug () << "<<keyPressEvent>> " <<
"[[Unknown button]]";
event->accept ();
}
@

OE0214

on Android, I did this:

void MainWindow::keyPressEvent(QKeyEvent *event)
{
	if (event->key() == Qt::Key_Back)
		qDebug() << "[[Back button]]";
	else if (event->key() == Qt::Key_Menu)
		qDebug() << "[[Menu button]]";
	else if (event->key() == Qt::Key_TopMenu)
		qDebug() << "[[Top menu button]]";
	else
		qDebug() << "[[some other button]]";

	event->accept();
}

I get a debug message for the back button, but not for the menu button...I also tried Qt::Key_TopMenu, but still nothing

nor do I get the "some other button" debug message when the menu button is pressed, so this method is not even being called when I press the menu button

this message must be handled somewhere else

can anyone help?

Thanks

uCampaign

In Qt 5.4.2 this is what i use and it works fine:

ApplicationWindow {
....
onClosing: {
if (Qt.platform.os == "android") {
close.accepted = false;
if (stack.depth > 1) stack.pop();
}
}
}

bbaker

C++ code. Gives the desired/standard effect on Android. Use a QWidget with a QStackedLayout in the main window.

    stackedLayout = new QStackedLayout;
    QWidget *c = new QWidget();
    first = new FirstForm(this );

    stackedLayout->addWidget( first );

    c->setLayout( stackedLayout );
    setCentralWidget( c );

Override the closeEvent in the header:

protected:
    void closeEvent(QCloseEvent *event);

Implement the code in the body:

void MainWindow::closeEvent(QCloseEvent *event) {

if( stackedLayout->currentIndex() > 0 ) {
    QWidget *top = stackedLayout->currentWidget();
    stackedLayout->removeWidget( top );

    event->ignore();
}

}

// QED

seyed

@uCampaign this is my enhanced version:

Window {
    //...
    onClosing: {
        if (Qt.platform.os === "android" || Qt.platform.os === "ios") {
            close.accepted = false;
            if (menu.isShown) menu.hide();
            else if (stackView.depth > 1) stackView.pop();
            else Qt.quit();
        }
    }
}

Thank you :)

kgregory

Does anyone know of a full example of an app that captures the back button? Maybe a github repo? None of these code snippets are working for me and I'm not sure why.