So I was working on a positioning app which needs GPS to be turned on. So I wanted a way to automatically turn on GPS in the background, if even possible with high accuracy or atleast have a popup window come up so the user can turn on the GPS right away. But sadly I couldn't find a single way to do so in QT, if there is a solution it's always written in Java. Can I somehow do it in QT too or import Java code in it?
Would I also be able to keep my GPS updates running in the background? Because as soon as I press the home button the updates stop to come up in the console with qDebug... or is it just the qDebug function that can't run when the app is not open?
Will I be able to use GPS in my Qt app?
First, check if the target platform has GPS and/or capable of resolving geo-coordinates. Next check the manual out: Qt Location. Mind that they refer to this functionality as 'location' so it maybe partially available even without actual GPS unit on device if there is another provider type (I guess partially and not for all platforms). I could only find this list of platforms supported:
Qt Location Classes for accessing GPS and other location services and
for mapping and navigation. Split off from the Qt 4 Mobility module of
Qt Location. Supported on Android, BlackBerry, iOS, Linux (using
GeoClue), Windows and Sailfish OS.
As for starting the GPS (location services provider) there is such entry for QML for sure called start() of PositionSource. It also implies one can find the same functionality in C++ as well.
Would I also be able to keep my GPS updates running in the background? Because as soon as I press the home button the updates stop to come up in the console with qDebug... or is it just the qDebug function that can't run when the app is not open?
Home button: it implies Android? Unclear what you ask but the Android app lifecycle is a bit different matter than that. The GPS will be working independently of your app but will the app respond to messages is more determined by Android.
Related
Problem summary
I'm attempting to establish a connection between HoloLens and an Android device, which worked sporadically in the beta-version of the MRTK.
However since moving to the MRTK RC1 (Also Refresh), I've encountered issues regarding the QR-scanning. When pressing connect, the two devices seemingly finds eachother, however when the wearer of the HoloLens1 looks directly into the QR-code, nothing happens. (the white dot and "Locating marker..." text is showing)
Background summary
1. The Setup:
Implemented working MRTK RC1 Refresh
Cloned Feature-SpectatorView separately, copying only the "MixedRealityToolkit.Extensions" folder to the MRTK project.
"Spectator View - HoloLens" prefab added to scene.
First pressing "HoloLens" in the PlatformSwitcher, building for HoloLens1, then switching to "Android" and exporting the project to Android Studio.
Building the .apk from Android Studio
(opencv binaries are downloaded and implemented since beta version, I haven't since changed them from when they worked the last time.)
2. The Proces:
On the HoloLens, I press the "Connect" button in which a white text appears saying "Locating Marker..."
The Android phone presses connect and it goes to "Waiting for User" then as soon as a HoloLens is connected, it switches immediately to a QR code that should be readible from said HoloLens.
Looking directly at the QR-code and nothing new happens, connection does not establish further.
I checked if something was not ticked in Player Settings/Capabilities, but I can't seem to find what the culprit would be. Did I forget something in this proces?
There are a few things that could be causing this issue.
If the Android device is showing a marker, this means the two devices have established a network connection and are communicating with one another. Typically, when I run spectator view I enable the following capabilities: "Internet (Client & Server), Internet (Client), Microphone, Pictures Library, Private Networks (Client & Server), Spatial Perception, Videos Library, Webcam" in the Package.appxmanifest in visual studio. Pressing "HoloLens" on spectator view's unity platform switcher should typically achieve enabling these capabilities, but sometimes the package.appxmanifest doesn't get updated correctly in the visual studio project with subsequent builds in Unity. You can fix this by deleting your visual studio directory and rebuilding the visual studio project in unity.
If these capabilities are checked in the package.appxmanifest, it may be that you rejected a capability request when first running the application. If you open Settings -> Privacy -> Camera on the HoloLens, you can check whether your deployed spectator view application has camera access granted. You should be able to enable the camera functionality here if it is disabled.
There have been changes to both MixedRealityToolkit and MixedRealityToolkit-Unity spectator view logic, so cloning these items at different points in time may cause functions to no longer resolve (We're hoping to consolidate this code into the same repo/commit history in the future to prevent this from continuing to happen). Typically, in the Unity logs there will be errors stating that a function was not found for SpectatorViewPlugin.dll if the dll functionality is not resolving correctly. It sounds like this is not the issue you are hitting if things worked previously. But if it does turn out the case, it may be that you need to rebuild the SpectatorViewPlugin.dll to match the feature/spectatorView code you are using.
If you recently copied the SpectatorViewPlugin.dll and its dependencies to a new unity project, it may be that they aren't getting registered as usable by the windows uwp unity player. Make sure these binaries are in a Plugins\WSA\x86 folder within your assets folder. Also check the *.dll.meta definitions in the unity inspector to ensure the dll's are declared as usable for the unity wsa player/x86 builds.
I'm making a BB10 app with a headless component that's normally supposed to run nonstop, except when a certain field in its QSettings changes (to save battery power).
I tried looking everywhere for the documentation. But I still can't find out how to make a headless app terminate itself.
You can get notified every time your settings file change using QFileSystemWatcher and calling bb::Application::instance()->quit() when a certain QSettings value changes. Here's an example from BlackBerry that uses QFileSystemWatcher in headless to get notification whenever the QSettings file changes.
I prefer using invocation or my own headless communication mechanism though, you can see an exemple of how I usually deals with terminating the headless app here.
Have a good day.
I have a problem about touch device's hot-plug.
I set the environment variable as below.
export QT_QPA_EVDEV_TOUCHSCREEN_PARAMETERS=/dev/input/ts_uinput:rotate=0
The "/dev/input/ts_uinput" is created by ts library's application "ts_uinput".
The touch function can work normally before I re-plug the USB touch device.
If I re-plug the USB touch device, the touch function doesn't work.
The "/dev/input/ts_uinput" still is created after I re-plug the USB touch device.
I also monitor the data in "/dev/input/ts_uinput" and it also has data report.
Why the Qt does not get the touch event after re-plug the USB touch device?
I would boldly guess that this is because Qt (the Qt evdev platform plugin) opens /dev/input/ts_uinput when the app start. When you replug the touch device, the file is recreated but the file handle held by Qt has become invalid. Making it work again would require Qt to close and reopen the handle.
You could try getting more info by enabling debug logs: http://doc.qt.io/qt-5/embedded-linux.html#debugging-input-devices
However, I do not know if this is a bug or a missing feature, you might want to contact the Qt interest mailing list or report a bug.
I have a Qt application, running under Xfce and other Linux desktops, which works well, except that the circulating "startup notification" icon is not dismissed when the app starts up, so that it persists for some time after the app main window is showing and complete.
I would assume that either the QApplication would by default dismiss the notification when the main window event loop starts, or I would call some method to do so. I can't find anything relevant in the Qt API documentation, or with google searches on Qt startup notification.
How can one dismiss the startup notification, in a Qt application.
Doesn't adding of
StartupNotify=false
to the .desktop file of your app solve the problem?.In KDE,
X-KDE-StartupNotify=false
works; perhaps XFCE has a similar variable.
The startup notification is sent automatically inside Qt when the first window is first shown (see src/plugins/platforms/xcb/qxcbscreen.cpp), but obviously, due to a bug, it does not work if there are quotes or the escape character (\) in the .desktop file in the path to the program.
In addition, if Terminal=true is presented, the environment variable DESKTOP_STARTUP_ID is deleted by xterm and does not reach your application, so it is better not to enable both Terminal and StartupNotify flags at the same time.
Was tested on MATE.
Problem background:
I have a Qt/QML Symbian application targeting Qt 4.7.4, that requires a QML Camera component. The current state of Camera component has a serious performance bug, where once initialized, in order to overlay the camera view on the screen, it forces the whole application to "raster" graphics system. Even when the camera element is closed and destroyed the application remains in raster graphics system, and the whole app takes a large performance hit, rendering it almost unusable (scrolling lists, navigating through pages... ). The problem is gone only after the application is closed and restarted again, which is not really helpful.
As it appears this will not be resolved any time soon (it is marked as resolved only for some small subset of devices, which I doubt as I have a fairly high-end symbian device that suffers the same bug), I have to look into alternatives and workarounds.
One plausible workaround idea I have is to create a separate application, one whose only job is to capture the required image, process it and then closes. Currently I can do this by externally calling the native device camera application, but this is not a viable production solution. The main application would then start this second external application and wait for the result.
The question: is this possible with Qt creator? Packaging two different applications, and deploying them with a single deployment unit, such that the user does not have a complicated installation procedure?
I would have liked to solve this problem with QtCreator a few months ago but I failed. I managed to package two different applications into a single sis file by studying the pkg file format and creating a pkg file containing both applications.
It is worth examining the pkg files generated by QMake for each application and studying the pkg file format.
It is possible to get QMake to generate the desired pkg file. See the documentation of variable DEPLOYMENT, especially the part where pkg_postrules is discussed.
You can add your signed SIS file to another package with this line in PKG:
#"sub.sis",(0x20000002)