Icon creates binding loop on implicitWidth and implicitHeight when used with QT_DEVICE_PIXEL_RATIO

[Andrea Bernabei]

Ubuntu UI Toolkit r1905

Description:
Using Icon without specifying an explicit size causes binding loops on implicitWidth (and also implicitHeight)

How to reproduce:

test case: QT_DEVICE_PIXEL_RATIO=2 qmlscene main.qml

where main.qml is:

import QtQuick 2.4
import Ubuntu.Components 1.3

MainView {
    id: gallery
    Icon {
        name: "add"
    }
}

[Tim Peeters (tpeeters)]

See if https://bugs.launchpad.net/ubuntu/+source/ubuntu-ui-toolkit/+bug/1553090 can be related, even though the Icon does not have a sensing area.

[Michael Zanetti (mzanetti)]

This does not only happen when using DEVICE_PIXEL_RATIO. Adjusted title.

[Andrea Bernabei (faenil)]

@Michael: does the testcase trigger a binding loop on your setup without specifying QT_DEVICE_PIXEL_RATIO?

I only get the binding loop warning when QT_DEVICE_PIXEL_RATIO is set, I don't get it when it's not.

[Michael Zanetti (mzanetti)]

yeah, I see that in like all of my apps where I haven't explicitly worked around it.

[Andrea Bernabei (faenil)]

Please try with the testcase, if that doesn't trigger it then the bug title needs adding QT_DEVICE_PIXEL_RATIO back, or you have to add another testcase that triggers it without QT_DEVICE_PIXEL_RATIO

[Michael Zanetti (mzanetti)]

Added a test case that prints the warning without QT_DEVICE_PIXEL_RATIO into the description

[Michael Zanetti (mzanetti)]

ok. I totally stand corrected... turns out, the apps I start on my laptop actually all have QT_DEVICE_PIXEL_RATIO set to 2 implicitly through QtCreator which is why I see this issue all the time. I'm so sorry for the noise. I'll revert all my changes to this bug.

In any case, we'll soon be enabling the use of QT_DEVICE_PIXEL_RATIO on the phones too so this is quite important nevertheless.

[Gerry Boland (gerboland)]

I've attached a branch I worked on for dynamic grid unit support. This rewrites the icon image loader to follow the exact behaviour of qt's image loader, and solved my icon sizing/blur issue. It needs tests though

[Tim Peeters (tpeeters)]

There is another branch doing seemingly the same changes https://code.launchpad.net/~ubuntu-sdk-team/ubuntu-ui-toolkit/trunk-fix-icon-svg-image-loading/+merge/286585

[Tim Peeters (tpeeters)]

Re-assigning to Lukas since he was already working on it.