SlotsLayout with Column as mainSlot: endless loop when resizing view so that Column has negative width

Bug #1630167 reported by Marco Trevisan (Treviño) on 2016-10-04
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Canonical System Image
ubuntu-ui-toolkit (Ubuntu)
Andrea Bernabei

Bug Description

With a simple code such as

import QtQuick 2.4
import Ubuntu.Components 1.3
import QtQuick.Window 2.0

Window {
    SlotsLayout {
        id: slotsLayout
        onHeightChanged: print("SlotsLayout height",height)
        width: parent.width
        mainSlot: Column {
            onHeightChanged: print("COlumn height",height)
            onWidthChanged: console.log("Column width", width)

            Rectangle {
                id: rect
                width: parent.width
                onWidthChanged: console.log("RECT WIDTH", width)
                onHeightChanged: console.log("RECT HEIGHT!", height)
                height: 5


Or something similar (, when resizing the view horizontally to only use few pixels, an infinite resizing loop starts and the view freezes.

Related branches

Andrea Bernabei (faenil) wrote :

info for my future self:
I investigated this bug a few days ago, when Trevinho first reported it directly to me.

It turns out the loop is triggered when the view is resized so that the column gets a *negative* width.

At that point you see columns height going 0 to 5 (which is rectangle's height) and back to 0, in a loop, and width going -X to 0 to -X again.

summary: - When SlotsLayout uses a Column as mainSlot and view is resized
- horizontally an inifinite resize loop starts
+ SlotsLayout with Column as mainSlot: endless loop when resizing view so
+ that Column has negative width
Andrea Bernabei (faenil) on 2016-10-07
Changed in ubuntu-ui-toolkit (Ubuntu):
status: Triaged → In Progress
Changed in ubuntu-ui-toolkit (Ubuntu RTM):
assignee: nobody → Andrea Bernabei (faenil)
importance: Undecided → Medium
status: New → In Progress
Changed in ubuntu-ui-toolkit (Ubuntu):
status: In Progress → Fix Committed
no longer affects: ubuntu-ui-toolkit (Ubuntu RTM)
Changed in canonical-devices-system-image:
status: New → Fix Committed
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package ubuntu-ui-toolkit - 1.3.2141+16.10.20161013.5

ubuntu-ui-toolkit (1.3.2141+16.10.20161013.5) yakkety; urgency=medium

  [ Zsombor Egri ]
  * Do not show focus frame on ListItem when clicked. Fixes LP: #1628855
  * Fix color used to test ListItem.highlighted. Fixes LP: #1624328

  [ Christian Dywan ]
  * Don't skip the entirety of tst_textfield.11.qml. Fixes LP: #1624340

  [ Andrea Bernabei ]
  * SlotsLayout: do not set mainSlot's implicitSize, set its real size instead
    Fixes LP: #1630167.

  [ Tim Peeters ]
  * Enable proper focus handling in the scrolling ActionBar. Fixes LP: #1575893

 -- Zoltán Balogh <email address hidden> Thu, 13 Oct 2016 17:16:31 +0000

Changed in ubuntu-ui-toolkit (Ubuntu):
status: Fix Committed → Fix Released
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