Resize problem at the core of QML

[peteritv]

Hi all!

Pre to this post was "QML SplitView - handleDelegate"

I managed (by trial and error) to come up with this code:

import QtQuick 2.6
import QtQuick.Controls 1.5
import QtQuick.Layouts 1.3

Item {
    id: mainItem
    anchors.fill: parent

    SplitView {
        id: splitMain
        orientation: Qt.Vertical
        anchors.fill: parent
        signal handleChanged
        property real ratio: 0.6

        Rectangle {
            id: r1
            width: {
                if (splitMain.orientation == Qt.Horizontal) {
                    console.log("width: " + splitMain.width)
                    return splitMain.width * splitMain.ratio
                }
            }
            height: {
                if (splitMain.orientation == Qt.Vertical) {
                    console.log("height: " + splitMain.height)
                    return splitMain.height * splitMain.ratio
                }
            }
            Text {
                text: splitMain.ratio.toFixed(2)
            }
            onWidthChanged: {
                if ((splitMain.orientation == Qt.Horizontal)
                        && splitMain.resizing)
                    splitMain.handleChanged()
            }
            onHeightChanged: {
                if ((splitMain.orientation == Qt.Vertical)
                        && splitMain.resizing)
                    splitMain.handleChanged()
            }
        }
        Rectangle {
            id: r2
            Layout.fillWidth: (splitMain.orientation == Qt.Horizontal) ? true : false
            Layout.fillHeight: (splitMain.orientation == Qt.Vertical) ? true : false
        }
        handleDelegate: Rectangle {
            width: (splitMain.orientation == Qt.Horizontal) ? 4 : 0
            height: (splitMain.orientation == Qt.Vertical) ? 4 : 0
            color: "red"
        }

        onHandleChanged: {
            ratio = (splitMain.orientation == Qt.Horizontal) ? r1.width / width : r1.height / height
            console.log("handle changed to ratio " + ratio.toFixed(2))
        }
    }
}

Please try this urself, without touching the splitview handle, and see that all resizes (including the splitview) like you would expect when you resize the main window.

Now try again, but now fiddle with the splitview first....

And now try to resize the containing window...

As you will see, the SplitView aspect is not kept...

Now, review my code, I think I made everything possible on Window resize, but it won't keep the aspect ratio of the SplitView.

So:

• either my splitMain is not informed of parent (size) changes
• Or there is something really wrong here

I am sure there are some experts here?

To be clear:

I assume that my anchors.fill parent will trigger something I can work with.

According to QML bindings and so, the resize of the parent should trigger something in my class... But alas... that does not happen.

When resizing the parent (without touching SplitView handle) is works ok, but after touching the SplitView handle, it does not.

Apparently my anchors.fill parent does not trigger anything?
When parent changes, what do I have to do?

This is probably a BUG too, right?
When parent changes, the SplitView should be signaled.

[Edit: Merged the other very short postings into this one -- @Wieland]

[SGaist]

Hi,

This is a community driven forum. If you want to get in the touch with the developers of Qt you should post on the interest mailing list.

If you think you may have found something, then you should also check the bug report system to see if it's something known.

[A Former User]

Hi! I've prepared a small example. The main point here is that using the handle breaks the binding to the rectangle's height property, so it must be restored after resizing.

main.qml

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.0

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

    About {
        anchors.fill: parent
    }
}

About.qml

import QtQuick 2.7
import QtQuick.Controls 1.5
import QtQuick.Layouts 1.3

SplitView {
    id: splitView
    orientation: Qt.Vertical

    // set inital ratio
    property real ratio : 0.33
    // usually you'd use data from your backend object for that
    // property real ratio : backend.ratio()

    onRatioChanged: {
        // inform backend about changed ratio
        // backend.setRatio(ratio)
    }

    onResizingChanged: {
        if (!resizing) {
            // update height
            ratio = topRect.height / splitView.height
            // restore binding
            topRect.height = Qt.binding(function() {return splitView.height * splitView.ratio})
        }
    }

    handleDelegate: Rectangle {
        height: 4
        color: "red"
    }

    Rectangle {
        id: topRect
        color: "pink"
        // initialize height. note that this is only valid until the handle is used.
        // using the handle breaks that binding
        height: splitView.height * splitView.ratio
    }

    Rectangle {
        id: buttomRect
        color: "plum"
        Layout.fillHeight: true
    }
}