How to recieve Qt signal entered() in MouseArea from Touch? - qt

Question

I use MouseArea for buttons in my QT app and need to know, when the user moves his finger on the touch on a button. On W7 using a mouse, I get this information with onEntered from MouseArea.
The problem: on the target platform with touchscreen, the entered-signal is only fired, when I press the MouseArea (first touch inside MouseArea), then move my finger out (exited-signal), then move the finger back in (entered-signal). But when the first touch is outside the area and I enter it, entered-signal is not fired.
I also tried MultiPointTouchArea with onTouchUpdated and onUpdated, same behaviour.
I am using Qt 5.5.1 on embedded linux.
Is there something I can do to make the MouseArea always fire the entered-signal? Or should I use something other than MouseArea or MultiPointTouchArea?
As a workaround I could think of a MouseArea on the complete window, with information where all the buttons are and checking on each positionChanged, if a button was entered, but I'm sure there must be a better solution.
Edit: When using a mouse on target platform, the entered-signal is fired when moving the mouse into the area.
This is my (simplified) code:
main.cpp
#include <QApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QtQml>
#include "uart_terminal.h"
int main(int argc, char *argv[])
{
system("mount /dev/mmcblk0p1 /mnt/sdcard/");
setenv("QT_QPA_EGLFS_PHYSICAL_WIDTH", "376", 1);
setenv("QT_QPA_EGLFS_PHYSICAL_HEIGHT", "301", 1);
QApplication app(argc, argv);
qmlRegisterType<UART_terminal>("com.uart", 1, 0, "UARTTerminal");
QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty("applicationDirPath", QGuiApplication::applicationDirPath());
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
return app.exec();
}
main.qml:
Window
{
id: rootWindow
visible: true
width: 1280
height: 1024
Rectangle
{
id: test
color: "red"
width: 300
height: 300
MouseArea
{
anchors.fill: parent
hoverEnabled: true
acceptedButtons: Qt.AllButtons
onEntered:
{
console.log("entered")
test.color = "blue"
}
onExited: test.color = "red"
onCanceled: console.log("canceled")
onPositionChanged:
{
console.log("pos changed, containsMouse", containsMouse)
}
}
/*MultiPointTouchArea
{
anchors.fill: parent
onTouchUpdated: console.log("touch updated")
onUpdated: console.log("touchlist updated")
}*/
}
}

Answer 1

So as I didn't find any other solution, I had to implement the mentioned work around. I put a MouseArea "buttonContainer" on the whole screen, behind all other MouseAreas. Note that I have to propagate the positionChanged signal from each MouseArea, otherwise it won't create my button-entered signal when I started the touch in one button and then enter another one.
onPositionChanged:
{
// propagate event to buttonContainer with absolute mouse position
var position = roundMouseArea.mapToItem(root)
buttonContainer.xOffsetMouse = position.x
buttonContainer.yOffsetMouse = position.y
buttonContainer.positionChanged(mouse)
}
Then in buttonContainer's onPositionChanged I have to check for all Buttons that are currenty visible if they were entered. Don't forget to map each buttons position again with btn.mapToItem(buttonContainer) and to reset x- and yOffsetMouse in buttonContainer's onPressed.
In my case I had to do much more stuff like
check if button is disabled anyways, although visible
remember enteredBtn
set bool for each button if it's already entered from my container, so I don't get entered-signal at each positionChanged while I stay in that button
also check for button exited
set btnPressed true or false accordingly, eg. also at buttonContainer's onReleased
reset enteredBtn to undefined accordingly and check for that, before referencing any method or property of enteredBtn (eg. at buttonContainer's onReleased)
I think that was all. Don't want to copy my whole code here, just mention some aspects you might also need to consider if you have the same issue.