f1b1773d0a
Problem description:
--------------------
Assume we have two properties, P1 and P2. Assume further that we assign
a binding to P2, so that it depends on P1. Let the binding additionally
capture some (non-QProperty) boolean, and only create the dependency to
P1 if the boolean is true.
The state afterwards is
P1:[p1vaue|firstObserver]
|
|
v
---[p2binding]
/
P2:[p2value|binding]
If the boolean is set to false, and P1 changes its value, we still
correctly re-evaluate the binding and update P2's value. However, during
binding evaluation we will notice that there is no further dependency
from P2 on P1, and remove its observer.
The state afterwards is
P1:[p1vaue|firstObserver=nullptr]
---[p2binding]
/
P2:[p2value|binding]
Then, during the notify phase, we traverse the observer's again,
starting from P1's firstObserver. Given that it is nullptr now, we never
reach P2's binding, and thus won't send a notification from it.
Fix:
----
We store a list of all visited binding-observers (in a QVarLengthArray,
to avoid allocations as long as possible). After the binding evaluation
phase, we then use that list to send notifications from every binding
that we visited. As we already have a list of all bindings, we no longer
need to recurse on binding-observes during the notification process;
instead, we only need to deal with static callbacks and ChangeHandlers.
The pre-existing notification logic is still kept for the grouped update
case, where we already have a list of all delayed properties, and should
therefore not encounter the same issue. Unifying its codepath with the
existing logic is left as an exercise for a later patch.
Fixes: QTBUG-105204
Task-number: QTBUG-104982
Pick-to: 6.4 6.3 6.2
Change-Id: I2951f7d9597f4da0b8560a64dfb834f7ad86e757
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Sami Shalayel <sami.shalayel@qt.io>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
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| .. | ||
| auto | ||
| baseline | ||
| benchmarks | ||
| global | ||
| libfuzzer | ||
| manual | ||
| shared | ||
| testserver | ||
| CMakeLists.txt | ||
| README | ||
This directory contains autotests and benchmarks based on Qt Test. In order
to run the autotests reliably, you need to configure a desktop to match the
test environment that these tests are written for.
Linux X11:
* The user must be logged in to an active desktop; you can't run the
autotests without a valid DISPLAY that allows X11 connections.
* The tests are run against a KDE3 or KDE4 desktop.
* Window manager uses "click to focus", and not "focus follows mouse". Many
tests move the mouse cursor around and expect this to not affect focus
and activation.
* Disable "click to activate", i.e., when a window is opened, the window
manager should automatically activate it (give it input focus) and not
wait for the user to click the window.