How to deploy qt5 qml plugin to android?

Question

I am trying to import TimeExample Qt Quick Extension Plugin from Qt 5.1.0 android installation.

libqmlqtimeexampleplugin.so is built sucessfully in build-plugins-Android_for_arm_GCC_4_6_Qt_5_1_0-Debug/imports

Then I created simple Qt Quick2 Application (built-in Elements) from Qt Creator. What should I add to application project file to get QML plugin in output ".apk" package?

Now it says:

W/Qt (23528): assets:/qml/TimeExampleTest/main.qml:2 (): assets:/qml/TimeExampleTest/main.qml:2:1: module "TimeExample" is not installed

main.qml

 import QtQuick 2.0

 import TimeExample 1.0 // import types from the plugin

 Rectangle {
    width: 360
    height: 360
    Text {
        text: qsTr("Hello World")
        anchors.centerIn: parent
    }
    MouseArea {
       anchors.fill: parent
        onClicked: {
          Qt.quit();
       }
    }

   Clock { // this class is defined in QML (imports/TimeExample/Clock.qml)

        Time { // this class is defined in C++ (plugin.cpp)
            id: time
      }

        hours: time.hour
      minutes: time.minute

    }
}

TimeExampleTest.pro

folder_01.source = qml/TimeExampleTest

 folder_01.target = qml

 folder_02.source = /home/artem/Projects/Veedo/Test/build-plugins-Android_for_arm_GCC_4_6_Qt_5_1_0-Debug/imports/TimeExample

 folder_02.target = imports

 DEPLOYMENTFOLDERS = folder_01 folder_02

 QML_IMPORT_PATH = /home/artem/Projects/Veedo/Test/build-plugins-Android_for_arm_GCC_4_6_Qt_5_1_0-Debug/imports/TimeExample

 SOURCES += main.cpp

 include(qtquick2applicationviewer/qtquick2applicationviewer.pri)

 qtcAddDeployment()

 OTHER_FILES += \
    android/src/org/kde/necessitas/ministro/IMinistro.aidl \
    android/src/org/kde/necessitas/ministro/IMinistroCallback.aidl \
    android/src/org/qtproject/qt5/android/bindings/QtActivity.java \
    android/src/org/qtproject/qt5/android/bindings/QtApplication.java \
    android/AndroidManifest.xml \
    android/version.xml \
    android/res/values-ja/strings.xml \
    android/res/values-rs/strings.xml \
    android/res/values-zh-rTW/strings.xml \
    android/res/values-fa/strings.xml \
    android/res/values-ru/strings.xml \
    android/res/values-fr/strings.xml \
    android/res/values-ro/strings.xml \
    android/res/values-el/strings.xml \
    android/res/values-ms/strings.xml \
    android/res/values-nb/strings.xml \
    android/res/values-et/strings.xml \
    android/res/values-pl/strings.xml \
    android/res/values-pt-rBR/strings.xml \
    android/res/values-es/strings.xml \
    android/res/values-id/strings.xml \
    android/res/values-de/strings.xml \
    android/res/values-it/strings.xml \
    android/res/values-zh-rCN/strings.xml \
    android/res/values/strings.xml \
    android/res/values/libs.xml \
    android/res/layout/splash.xml \
    android/res/values-nl/strings.xml

Answer 1

With Qt 5.3, we managed to get our QML plugin recognized by a Qt Android app only by deploying the plugin to the QT_INSTALL_QML directory where official Qt QML modules reside. This directory is /opt/Qt/5.3/android_armv7/qml in our case.

Plugin Side

Our .pro file for the plugin looks like:

TEMPLATE = lib
TARGET = prova
QT += qml quick multimedia
CONFIG += qt plugin c++11 console
CONFIG -= android_install
TARGET = $$qtLibraryTarget($$TARGET)
uri = com.mycompany.qmlcomponents

# Input
SOURCES += \
    src1.cpp \
    src2.cpp

HEADERS += \
    src1.h \
    src2.h

##The below is generated automatically by Qt Creator when you create a new "Qt Quick 2 Extension Plugin" project for Android

#Copies the qmldir file to the build directory
!equals(_PRO_FILE_PWD_, $$OUT_PWD) {
    copy_qmldir.target = $$OUT_PWD/qmldir
    copy_qmldir.depends = $$_PRO_FILE_PWD_/qmldir
    copy_qmldir.commands = $(COPY_FILE) \"$$replace(copy_qmldir.depends, /, $$QMAKE_DIR_SEP)\" \"$$replace(copy_qmldir.target, /, $$QMAKE_DIR_SEP)\"
    QMAKE_EXTRA_TARGETS += copy_qmldir
    PRE_TARGETDEPS += $$copy_qmldir.target
}

#Copies the qmldir file and the built plugin .so to the QT_INSTALL_QML directory
qmldir.files = qmldir
unix {
    installPath = $$[QT_INSTALL_QML]/$$replace(uri, \\., /)
    qmldir.path = $$installPath
    target.path = $$installPath
    INSTALLS += target qmldir
}

Our qmldir (in the plugin source tree root) file is:

module com.mycompany.qmlcomponents
plugin prova

Application Side

The .pro file looks like:

TEMPLATE = app

QT += qml quick widgets multimedia

CONFIG+= console
SOURCES += main.cpp

RESOURCES += qml.qrc

# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =
# Default rules for deployment.
include(deployment.pri)

contains(ANDROID_TARGET_ARCH,armeabi-v7a) {
    ANDROID_EXTRA_LIBS = \
        /opt/Qt/5.3/android_armv7/qml/com/mycompany/qmlcomponents/libprova.so
}

We don't actually know if the inclusion of the extra libprova.so is necessary. It's most probably not.

The main.cpp looks like:

#include <QApplication>
#include <QQmlApplicationEngine>
int main(int argc, char *argv[]){
    QApplication app(argc, argv);
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
    return app.exec();
}

The main.qml just includes the plugin like:

import QtQuick 2.2
import QtQuick.Controls 1.1
import QtMultimedia 5.0

import com.mycompany.qmlcomponents 1.0

...

Building and Deployment

The way we build and deploy the plugin is to qmake (from the android-armv7 toolchain of Qt), then make install. It installs the qmldir file and the plugin .so to the QT_INSTALL_QML directory.

The way we build and deploy the project that uses the plugin is to qmake (again, from the android-armv7 toolchain of Qt), then make install INSTALL_ROOT=. (installs to build directory), then run androiddeployqt. The last command creates the Android project structure with the qmldirs in assets/ and libraries in libs/ and bundles the whole thing in an apk via ant. For the details of this procedure, refer to http://qt-project.org/wiki/Android.

In short, we were only able to get our QML plugin recognized inside an Android project by putting it inside the private Qt qml directory.