StackView.pop() from Item on Stack

Stoepsler

Hello there,

I have a problem with the StackView.
What I want to do is, to pop an Item from the stack triggered inside the item on the stack.

Example:
main.qml:

import QtQuick 2.4
import QtQuick.Controls 1.4

Item {
  id: appWidget
  width: 800
  height: 400

  ListModel {
    id:availableApps

    ListElement{
      name: "App1"
      app: "App1/App1.qml"
    }
  }

  GridView {
    id: appsGrid
    anchors.fill: parent
    anchors.margins: 20
    clip: true
    cellHeight: appsGrid.height/3
    cellWidth: appsGrid.width/5
    model: availableApps
    delegate: AppButton {onClicked: appStack.push(Qt.resolvedUrl(app))} // when clicked -> push view
  }

  StackView {
    id: appStack
    width: parent.width
    height: parent.height
  }
}

AppButton.qml

import QtQuick 2.4

Item {
  id: appButton
  width: GridView.view.cellWidth
  height: GridView.view.cellHeight

  signal clicked

  Text {
    id: appButtonLabel
    width: parent.width

    anchors.top: appButtonImage.bottom
    horizontalAlignment: Text.AlignHCenter

    font.pointSize: 14

    text: qsTr(name)
  }

  MultiPointTouchArea {
    width: parent.width
    height: parent.height

    onReleased: appButton.clicked()
  }
}

App1.qml

import QtQuick 2.4

Item {
  id:alignment
  height: parent.height
  width: parent.width

  Rectangle {
    id: rec
    anchors.fill: parent
    color: "yellow"
  }

  MultiPointTouchArea {
    anchors.fill: parent

    onReleased: rec.color = "orange" // here I want to pop the item from the appStack
  }
}

I tried following things:

call pop() from within the Item via Stack.view.pop() as the Item knows, it is on a Stack, but that is not possible ...
emit a signal and than handle it with currentItem.onSignal in the StackView but that also didn't work.
I also tried if (appStack) appStack.pop() inside the item

As the rec.color = "orange" is working, I don't think its an focus problem.

The application shall later run on a touchscreen device without a keyboard.

literA2

how did you capture a signal from StackView?

Stoepsler

You mean from the Item on the Stack? I didn't, because it isn't possible or at least I don't know how.
What I had done is, that I tried to capture it, but didn't found a way to do it properly.

This is how I tried to emit the signal:
In App1.qml I've added signal clicked that was called instead of the color change with alignment.clicked()

This is how I tried to capture it:
In the StackView declaration I tried to call currentItem.onClicked: appStack.pop(),currentItem.item.onClicked: appStack.pop() and currentItem.Stack.view.pop() as I have seen somewhere but nether it of was accepted as valid qml code ...

Stoepsler

So, after playing around and a another few looks into the qt touch-gallery example, where they do exactly the with on of their buttons, I found a working solution and maybe a bug in the StackView.
But thats I'm not really sure of. Maybe someone with more experience in QtQuick and StackView can confirm it ;)

After adding a Text in App1 that displays the current stackdepth, I was surprised it shows a value of 2 even when I've only added one Item.
And from this visibility of the depth, I was able to see that the call if (appStack) appStack.pop() call at onReleased: in App1 is actually working. The last Item was popped so that that there was only one left on the stack. As those were both yellow I havn't seen the pop effect before.

What I'm not sure about now:

As I havn't found a rule, that a StackViewalways needs a initialItem, is it working as intended, that the first item to be added on a empty StackView is added twice?
Is it working as intended, that the last item on the Stackview can't be popped with pop() but must be popped with clear() ?

If anyone with more experience in QtQuick and the usage of StackView knows anything about this points, feel free to explain your knowledge/thougths.

If this is really a bug in StackView I would report it after confirmation ;)

PS: as a workaround for now I'm using onReleased: appStack.depth > 1 ? appStack.pop() : appStack.clear() in App1.
Like this both instances on the Stack are popped at the same time.