Android support

[mappu]

Miqt should support easily compiling Qt Widgets apps for Android.

[mappu]

Work in progress 2024-09-21

1. Create docker container

FROM raymii/qt:5.15-android-source

RUN wget 'https://go.dev/dl/go1.23.1.linux-amd64.tar.gz' && \
	tar x -C /usr/local/ -f go1.23.1.linux-amd64.tar.gz && \
	rm go1.23.1.linux-amd64.tar.gz

ENV PATH=/usr/local/go/bin:/opt/cmake/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/Qt-5.15.13/bin:/opt/android-sdk/cmdline-tools/tools/bin:/opt/android-sdk/tools:/opt/android-sdk/tools/bin:/opt/android-sdk/platform-tools

ENV CC=/opt/android-sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android30-clang
ENV CXX=/opt/android-sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android30-clang++
ENV CGO_ENABLED=1
ENV GOOS=android
ENV GOARCH=arm64
ENV GOFLAGS=-buildvcs=false

2. Create androiddeployqt properties file (these paths are specialized for the above docker container)

{
  "_description": "Available fields are documented in the template file at /usr/local/Qt-5.15.13/mkspecs/features/android/android_deployment_settings.prf",
  "application-binary": "handbindings",
  "architectures": {
    "arm64-v8a" : "aarch64-linux-android"
  },
  
  "android-extra-libs": "/opt/android_openssl/ssl_1.1/arm64-v8a/libssl.so,/opt/android_openssl/ssl_1.1/arm64-v8a/libssl_1_1.so,/opt/android_openssl/ssl_1.1/arm64-v8a/libcrypto.so,/opt/android_openssl/ssl_1.1/arm64-v8a/libcrypto_1_1.so",
  
  "android-min-sdk-version": "23",
  "android-target-sdk-version": "30",
  "ndk": "/opt/android-sdk/ndk/22.1.7171670",
  "ndk-host": "linux-x86_64",
  "qml-root-path": "/miqt/cmd/handbindings",
  "qt": "/usr/local/Qt-5.15.13/",
  "sdk": "/opt/android-sdk",
  "sdkBuildToolsRevision": "30.0.2",
  "stdcpp-path": "/opt/android-sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/",
  "tool-prefix": "llvm",
  "toolchain-prefix": "llvm",
  "useLLVM": true
}

3. Patch updated android_cflags.go

//+build android

package main

/*

#cgo CXXFLAGS: -DQT_WIDGETS_LIB -I/usr/local/Qt-5.15.13/include/QtWidgets -I/usr/local/Qt-5.15.13/include/ -I/usr/local/Qt-5.15.13/include/QtCore -DQT_GUI_LIB -I/usr/local/Qt-5.15.13/include/QtGui -DQT_CORE_LIB
#cgo LDFLAGS: /usr/local/Qt-5.15.13/lib/libQt5Widgets_arm64-v8a.so /usr/local/Qt-5.15.13/lib/libQt5Gui_arm64-v8a.so /usr/local/Qt-5.15.13/lib/libQt5Core_arm64-v8a.so

// or

#cgo CXXFLAGS: -fPIC -DQT_WIDGETS_LIB -I/usr/local/Qt-5.15.13/include/QtWidgets -I/usr/local/Qt-5.15.13/include/ -I/usr/local/Qt-5.15.13/include/QtCore -DQT_GUI_LIB -I/usr/local/Qt-5.15.13/include/QtGui -DQT_CORE_LIB
#cgo LDFLAGS: /usr/local/Qt-5.15.13/lib/libQt5Widgets_arm64-v8a.so /usr/local/Qt-5.15.13/lib/libQt5Gui_arm64-v8a.so /usr/local/Qt-5.15.13/lib/libQt5Core_arm64-v8a.so /usr/local/Qt-5.15.13/lib/libQt5Svg_arm64-v8a.so

*/
import "C"

4. Enter docker container

docker run --rm -v $(pwd):/miqt -it raymii/qt:5.15-android-source

5. Compile Go app to android .so

go build -ldflags "-s -w" -o android-build/libs/arm64-v8a/libhandbindings_arm64-v8a.so

# or

go build -buildmode c-shared -ldflags "-s -w -extldflags -Wl,-soname,libhandbindings_arm64-v8a.so" -o android-build/libs/arm64-v8a/libhandbindings_arm64-v8a.so

6. Package android .so with Qt libraries as .apk bundle

androiddeployqt --input ./android-deployment-settings.json --output ./android-build/

# Can add --release

However, the resulting app segfaults on my test device (Android 13):

*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
LineageOS Version: '20.0-20231031-NIGHTLY-beryllium'
Build fingerprint: 'Xiaomi/beryllium/beryllium:10/QKQ1.190828.002/V12.0.3.0.QEJMIXM:user/release-keys'
Revision: '0'
ABI: 'arm64'
Timestamp: 2024-09-22 13:07:14.699278279+1200
Process uptime: 582s
Cmdline: org.qtproject.example.handbindings
pid: 23128, tid: 25894, name: qtMainLoopThrea  >>> org.qtproject.example.handbindings <<<
uid: 10316
signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0000000000000000
Cause: null pointer dereference
    x0  0000000000000001  x1  0000007310c1be38  x2  00000075e49d354c  x3  0000007310c1bcf8
    x4  00000000000000e8  x5  0000007310c1b0e0  x6  0000000000000001  x7  002f003a00730074
    x8  0000000000000000  x9  0000000000000001  x10 0000000000000000  x11 0000000000000002
    x12 00000000000064df  x13 0000000000000001  x14 0000000000000000  x15 0000000000002f0a
    x16 0000000000000001  x17 00000075e493dfc0  x18 00000072b2d26000  x19 0000000000000001
    x20 00000072aa5f9c10  x21 00000072aa5f9000  x22 0000007310c1d000  x23 0000000000000000
    x24 0000000000000000  x25 000000734dd38f50  x26 0000007310c1c79c  x27 0000007310c1c798
    x28 0000007310c1c6a0  x29 0000007310c1c640
    lr  00000072aa51bc58  sp  0000007310c1bdf0  pc  0000000000000000  pst 0000000060000000
backtrace:
      #00 pc 0000000000000000  <unknown>
      #01 pc 0000000000056c54  /data/app/~~N3A0yPAyQ7_g_C-96KZRUA==/org.qtproject.example.handbindings-0Vnj7BGCGkKrnewuC-pgTg==/lib/arm64/libplugins_platforms_qtforandroid_arm64-v8a.so (BuildId: 15bfa0d5f5d097b55236b90f87c48822cfbd0789)