[Development] [Qt Quick] Automatically restoring focus to last focused item
Mitch Curtis
mitch.curtis at qt.io
Mon May 9 13:35:11 CEST 2016
Thanks for the reply, Andrew.
It looks like the contentItem of QQuickWindow is already a focus scope [1]:
contentItemPrivate->flags |= QQuickItem::ItemIsFocusScope;
Shouldn’t that already work, then?
If I set QT_LOGGING_RULES= qt.quick.focus=true, and use the following example, I get the output below:
http://pastebin.com/X9JMcpGh
This is printed when the application has started:
qt.quick.focus: QQuickWindowPrivate::setFocusInScope():
qt.quick.focus: scope: QQuickRootItem(0x1e25bec0000)
qt.quick.focus: scopeSubFocusItem: QObject(0x0)
qt.quick.focus: item: QQuickFocusScope_QML_0(0x1e25bec66c0)
qt.quick.focus: activeFocusItem: QObject(0x0)
qt.quick.focus: QQuickWindowPrivate::setFocusInScope():
qt.quick.focus: scope: QObject(0x0)
qt.quick.focus: item: QQuickRootItem(0x1e25bec0000)
qt.quick.focus: activeFocusItem: QObject(0x0)
qml: activeFocusItem QQuickFocusScope_QML_0(0x1e25bec66c0)
This is printed when I open the menu:
qt.quick.focus: QQuickWindowPrivate::setFocusInScope():
qt.quick.focus: scope: QQuickToolBar(0x1e25bec2dc0)
qt.quick.focus: scopeSubFocusItem: QObject(0x0)
qt.quick.focus: item: QQuickToolButton(0x1e25bec2a60)
qt.quick.focus: activeFocusItem: QQuickFocusScope_QML_0(0x1e25bec66c0)
qt.quick.focus: QQuickWindowPrivate::setFocusInScope():
qt.quick.focus: scope: QQuickRootItem(0x1e25bec0000)
qt.quick.focus: scopeSubFocusItem: QQuickFocusScope_QML_0(0x1e25bec66c0)
qt.quick.focus: item: QQuickToolBar(0x1e25bec2dc0)
qt.quick.focus: activeFocusItem: QQuickFocusScope_QML_0(0x1e25bec66c0)
qml: activeFocusItem QQuickToolButton(0x1e25bec2a60)
qml: @@@@@@@@@ clicked menu toolbutton
qt.quick.focus: QQuickWindowPrivate::setFocusInScope():
qt.quick.focus: scope: QQuickRootItem(0x1e25bec0000)
qt.quick.focus: scopeSubFocusItem: QQuickToolBar(0x1e25bec2dc0)
qt.quick.focus: item: QQuickPopupItem(0x1e25bec29a0)
qt.quick.focus: activeFocusItem: QQuickToolButton(0x1e25bec2a60)
qml: activeFocusItem QQuickPopupItem(0x1e25bec29a0)
And this is printed when I close the menu:
qt.quick.focus: QQuickWindowPrivate::clearFocusInScope():
qt.quick.focus: scope: QQuickRootItem(0x1e25bec0000)
qt.quick.focus: item: QQuickPopupItem(0x1e25bec29a0)
qt.quick.focus: activeFocusItem: QQuickPopupItem(0x1e25bec29a0)
qml: activeFocusItem QQuickRootItem(0x1e25bec0000)
qml: @@@@@@@@@ closed menu
If I apply the following patch to qtquickcontrols2, the root item becomes the active focus item, and so pressing alt does nothing:
diff --git a/src/quicktemplates2/qquickapplicationwindow.cpp b/src/quicktemplates2/qquickapplicationwindow.cpp
index 401313d..cb8a2fa 100644
--- a/src/quicktemplates2/qquickapplicationwindow.cpp
+++ b/src/quicktemplates2/qquickapplicationwindow.cpp
@@ -424,6 +424,7 @@ QQuickItem *QQuickApplicationWindow::contentItem() const
QQuickApplicationWindowPrivate *d = const_cast<QQuickApplicationWindowPrivate *>(d_func());
if (!d->contentItem) {
d->contentItem = new QQuickItem(QQuickWindow::contentItem());
+ d->contentItem->setFlag(QQuickItem::ItemIsFocusScope);
d->relayout();
}
return d->contentItem;
[1] http://code.qt.io/cgit/qt/qtdeclarative.git/tree/src/quick/items/qquickwindow.cpp#n483
From: Andrew den Exter [mailto:andrew.den.exter at qinetic.com.au]
Sent: Friday, 6 May 2016 1:38 PM
To: Mitch Curtis <mitch.curtis at qt.io>
Cc: development at qt-project.org
Subject: Re: [Development] [Qt Quick] Automatically restoring focus to last focused item
That's a very universal solution to a specific problem and one that's going to have all kinds of unintended consequences. Without knowing why focus was taken from an item and given to another and why that other object relinquished focus it's impossible to know whether focus should be restored to that first item. That memory may have to go back more than one item as well, after all if you open one menu then another then the previous focus item is the first window and that's obviously not what you want to give focus to.
What you want to do instead is introduce a FocusScope to ApplicationWindow. If the window's content item is a focus scope then giving focus to a menu which is outside of this scope will not affect focus within the scope, then whatever logic closes the menu can give focus back to the content item and that will implicitly return active focus to your item in the window body.
Andrew
On Fri, May 6, 2016 at 12:08 AM, Mitch Curtis <mitch.curtis at qt.io<mailto:mitch.curtis at qt.io>> wrote:
Consider the example below (requires Qt 5.7):
import QtQuick 2.6
import QtQuick.Layouts 1.1
import QtQuick.Window 2.2
import QtQuick.Controls 2.0
ApplicationWindow {
width: 400
height: 200
visible: true
onActiveFocusItemChanged: print("activeFocusItem", activeFocusItem)
header: ToolBar {
RowLayout {
focus: false
implicitWidth: children[0].implicitWidth
implicitHeight: children[0].implicitHeight
ToolButton {
text: qsTr("File")
onClicked: fileMenu.open()
Menu {
id: fileMenu
y: parent.height
MenuItem {
text: qsTr("New")
}
MenuItem {
text: qsTr("open")
}
MenuItem {
text: qsTr("Close")
}
}
}
}
}
FocusScope {
id: focusScope
focus: true
anchors.fill: parent
property bool toggled: false
onToggledChanged: print("toggled", toggled)
Keys.onPressed: {
if (event.modifiers === Qt.AltModifier) {
focusScope.toggled = true;
}
}
Keys.onReleased: {
if ((event.modifiers === Qt.AltModifier || event.key === Qt.Key_Alt) && !event.isAutoRepeat) {
focusScope.toggled = false;
}
}
RowLayout {
anchors.centerIn: parent
Button {
id: penButton
text: qsTr("Pen")
highlighted: !focusScope.toggled
}
Button {
id: eyedropperButton
text: qsTr("Eyedropper")
highlighted: focusScope.toggled
}
}
}
}
The idea is that holding the Alt key down will toggle between two "modes". The mode is indicated by a highlighted button.
Try switching between the buttons. Now open the menu by clicking the "File" button. The menu will receive focus and the focus scope will lose it. If you then close the menu and try to switch between the buttons again, it won't work because the focus scope never regained focus (the root item now has it). This is explained here [1]:
"When a QML Item explicitly relinquishes focus (by setting its focus property to false while it has active focus), the system does not automatically select another type to receive focus. That is, it is possible for there to be no currently active focus."
I'm not sure if "explicitly relinquishes focus" is exactly what's happening here, though. The FocusScope loses focus because something else was open temporarily. So now the developer has no other option than to listen to e.g. the menu visibility changes and explicitly set focus on the FocusScope accordingly. That's pretty gross if you ask me. I think we can do better. Specifically, I think that we should remember the last focused item, and give that focus, rather than give it to the root item. The question is, would it be an acceptable change for Qt 5? I'd assume that users are already working around this anyway, and so the fix wouldn't hurt.
[1] http://doc.qt.io/qt-5/qtquick-input-focus.html
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