From 8d4414b58f7e24db7480ffe896324c235bd5ebd7 Mon Sep 17 00:00:00 2001
From: Richard Moe Gustavsen <richard.gustavsen@digia.com>
Date: Fri, 11 Jan 2013 11:27:33 +0100
Subject: [PATCH] PageStack: add recursion guard
We need to protect the page stack while it updates properties to
ensure that the update is atomic. Otherwise the user can e.g
push a new page upon receiving Page.onStatusChanged or
Page.onCompleted, which will recursively start a new transition
while we prepare for another. Calling push/pop while the transition
runs is fine.
Change-Id: Ib9453b1a61f8c8cee19f5e748bb75a1a30614119
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>
---
src/qtdesktop/PageStack.qml | 42 ++++++++++++++++++++++++++++++-------
tests/manual/PageStack.qml | 7 ++++++-
2 files changed, 41 insertions(+), 8 deletions(-)
diff --git a/src/qtdesktop/PageStack.qml b/src/qtdesktop/PageStack.qml
index 5b41f145c..7eade6dbb 100644
--- a/src/qtdesktop/PageStack.qml
+++ b/src/qtdesktop/PageStack.qml
@@ -547,6 +547,8 @@ Item {
// Note: we support two different APIs in this function; The old meego API, and
// the new "property list" API. Hence the reason for hiding the fact that you
// can pass more arguments than shown in the signature:
+ if (__recursionGuard(true))
+ return
var properties = arguments[1]
var immediate = arguments[2]
var replace = arguments[3]
@@ -584,6 +586,7 @@ Item {
push: true
}
__performPageTransition(transition)
+ __recursionGuard(false)
return __currentPage
}
@@ -625,6 +628,9 @@ Item {
if (page === __currentPage)
return
+ if (__recursionGuard(true))
+ return
+
var outElement = JSArray.pop()
var transitionElement = outElement
var inElement = JSArray.current()
@@ -654,12 +660,16 @@ Item {
push: false
}
__performPageTransition(transition)
+ __recursionGuard(false)
return outElement.page;
}
/*! Remove all pages from the stack. No animations will be applied. */
function clear() {
- completeTransition()
+ if (__recursionGuard(true))
+ return
+ if (__currentTransition)
+ __currentTransition.animation.complete()
__currentPage = null
var count = __depth
for (var i=0; i<count; ++i) {
@@ -667,6 +677,7 @@ Item {
if (element.page)
__cleanup(element);
}
+ __recursionGuard(false)
}
/*! Search for a specific page inside the stack. \a func will
@@ -712,8 +723,11 @@ Item {
*/
function completeTransition()
{
+ if (__recursionGuard(true))
+ return
if (__currentTransition)
__currentTransition.animation.complete()
+ __recursionGuard(false)
}
/********* DEPRECATED API *********/
@@ -735,6 +749,8 @@ Item {
property int __depth: 0
/*! \internal Stores the transition info while a transition is ongoing */
property var __currentTransition: null
+ /*! \internal Stops the user from pushing pages while preparing a transition */
+ property bool __guard: false
/*! \internal */
Component.onCompleted: {
@@ -744,10 +760,21 @@ Item {
/*! \internal */
Component.onDestruction: {
- completeTransition()
+ if (__currentTransition)
+ __currentTransition.animation.complete()
__currentPage = null
}
+ function __recursionGuard(use)
+ {
+ if (use && __guard) {
+ console.warn("Warning: PageStack: You cannot push/pop recursively!")
+ console.trace()
+ return true
+ }
+ __guard = use
+ }
+
/*! \internal */
function __loadElement(element)
{
@@ -858,12 +885,13 @@ Item {
/*! \internal */
function __performPageTransition(transition)
{
- // Animate page in "outElement" out, and page in "inElement" in. Ensure entering page is
- // loaded. Loading a page can result in the loaded page recursively pushing or popping
- // other pages, so we need to check for this.
- completeTransition()
+ // Animate page in "outElement" out, and page in "inElement" in. Set a guard to protect
+ // the user from pushing new pages on signals that will fire while preparing for the transition
+ // (e.g Page.onCompleted, Page.onStatusChanged, Page.onIndexChanged etc). Otherwise, we will enter
+ // this function several times, which causes the pages to be half-way updated.
+ if (__currentTransition)
+ __currentTransition.animation.complete()
__loadElement(transition.inElement)
- var currentElement = JSArray.current()
transition.name = transition.replace ? "replaceAnimation" : (transition.push ? "pushAnimation" : "popAnimation")
var enterPage = transition.inElement.page
diff --git a/tests/manual/PageStack.qml b/tests/manual/PageStack.qml
index 2ff8492c5..b8492a837 100644
--- a/tests/manual/PageStack.qml
+++ b/tests/manual/PageStack.qml
@@ -135,7 +135,8 @@ Window {
Page {
id: page
Component.onDestruction: console.log("destroyed component page: " + index)
-
+ property bool pushFromOnCompleted: false
+ Component.onCompleted: if (pushFromOnCompleted) pageStack.push(pageComponent)
//pageTransition: rotateTransition
Rectangle {
@@ -178,6 +179,10 @@ Window {
text: "Push component page with destroyOnPop == false"
onClicked: pageStack.push({page:pageComponent, destroyOnPop:false})
}
+ Button {
+ text: "Push from Page.onCompleted"
+ onClicked: pageStack.push({page:pageComponent, properties:{pushFromOnCompleted:true}})
+ }
Button {
text: "Pop"
onClicked: pageStack.pop()
--
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