Chap05 runs on desktop but not on mobile.

[RoyeA]

Love the book. It teachs me a lot.
I'm trying to run the chap05 app on an Android device. It fails to start due to the followings:

E AndroidRuntime: FATAL EXCEPTION: qtMainLoopThread
E AndroidRuntime: Process: org.qtproject.example.gallery_mobile, PID: 25728
E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed: library "libgallery-core_armeabi-v7a.so" not found
E AndroidRuntime: 	at java.lang.Runtime.load0(Runtime.java:897)
E AndroidRuntime: 	at java.lang.System.load(System.java:1505)
E AndroidRuntime: 	at org.qtproject.qt5.android.QtNative$4.run(QtNative.java:505)
E AndroidRuntime: 	at org.qtproject.qt5.android.QtThread$2.run(QtThread.java:87)
E AndroidRuntime: 	at org.qtproject.qt5.android.QtThread$1.run(QtThread.java:61)
E AndroidRuntime: 	at java.lang.Thread.run(Thread.java:761)

---

Looking in the apk file, and listing all libs, the libgallery-core_armeabi-v7a.so is missing.
Two questions:

1. How do I configure the build to include the core library within the apk ?
2. When compiling the android version, the core library has a different name than just gallery-core. How do I set it up in the .pro file?

Thank you,
Roye Avidor

[GuillaumeLazar]

Hello Roye,
I'm glad that you like the book.

The first edition of the book was written for Qt 5.7 and the second edition wad updated for Qt 5.11. I think you encounters issues because you are using a Qt version >= 5.14.

Starting Qt version 5.14 , Qt for Android now use Android Clang Multi-Abi that generate multi ABI binaries. And the name of a library is postfix with the name of the ABI (armeabi-v7a, amr6-v8a, x86, x86_64, ...).

• The quick and easy solution is to use the Qt version 5.11 (same that the second edition of the book) and an adapted android kit e.g "armeabi_v7a" (prior to the Android clang multi ABI feature). You will see in the apk that you get the Qt libs and your project lib "libgallery-core.so" in the APK.

• The slow and better solution is to update the "gallery-mobile.pro" to handle the android multi abi feature and use a Qt version 5.15.2 and android kit clang multi ABI. And maybe also update the source code due to Qt changes:

1. You have some modifications to do on the "gallery-mobile.pro". You should use the qmake variable "$$ANDROID_ABIS" that will automatically set the correct ABI name during the qmake process.

# Removed part. Qt version 5.11  (single ABI)
# LIBS += -L$$OUT_PWD/../gallery-core/ -lgallery-core
# contains(ANDROID_TARGET_ARCH,x86) {
#     ANDROID_EXTRA_LIBS = \
#         $$[QT_INSTALL_LIBS]/libQt5Sql.so
# }

# Updated part. >= Qt version 5.14  (multi ABI)
android: {
    LIBS += -L$$OUT_PWD/../gallery-core/ -lgallery-core_$$ANDROID_ABIS

    ANDROID_EXTRA_LIBS = \
        $$[QT_INSTALL_LIBS]/libQt5PrintSupport_$${ANDROID_ABIS}.so \
        $$[QT_INSTALL_LIBS]/libQt5Sql_$${ANDROID_ABIS}.so \
        $$OUT_PWD/../gallery-core/libgallery-core_$${ANDROID_ABIS}.so \
} else {
    LIBS += -L$$OUT_PWD/../gallery-core/ -lgallery-core
}

2. Nothing should be done on the "gallery-core.pro", just check that the "libgallery-core_armeabi-v7a.so" is generated

You can now check the generated APK, you hould get the "libgallery-mobile_armeabi-v7a.so" file in the APK.

The fix above will correct your compilation issue with >=Qt 5.14 for Android. But I guess you will get others issues and it can require some time to update a source code software to Qt version to another one.

If you update it to a recent Qt version, feel free to create a PR on the second edition github repo (this first edition github is deprecated and not updated) : https://github.com/PacktPublishing/Mastering-Qt-5-Second-Editon