Qt: add Android packaging support

Introduce an android directory under qt and allow one to package bitcoin-qt for Android by running make apk.
Add bitcoin-qt Android build instructions.

16 files changed, 174 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 0b176e6039..1b06035815 100644
--- a/configure.ac
+++ b/configure.ac
@@ -734,6 +734,21 @@ case $host in
    *android*)
      dnl make sure android stays above linux for hosts like *linux-android*
      TARGET_OS=android
+     case $host in
+       *x86_64*)
+          ANDROID_ARCH=x86_64
+          ;;
+        *aarch64*)
+          ANDROID_ARCH=arm64-v8a
+          ;;
+        *armv7a*)
+          ANDROID_ARCH=armeabi-v7a
+          ;;
+        *i686*)
+          ANDROID_ARCH=i686
+          ;;
+        *) AC_MSG_ERROR("Could not determine Android arch") ;;
+      esac
      ;;
    *linux*)
      TARGET_OS=linux
@@ -1844,6 +1859,7 @@ AC_SUBST(HAVE_BUILTIN_PREFETCH)
 AC_SUBST(HAVE_MM_PREFETCH)
 AC_SUBST(HAVE_STRONG_GETAUXVAL)
 AC_SUBST(HAVE_WEAK_GETAUXVAL)
+AC_SUBST(ANDROID_ARCH)
 AC_CONFIG_FILES([Makefile src/Makefile doc/man/Makefile share/setup.nsi share/qt/Info.plist test/config.ini])
 AC_CONFIG_FILES([contrib/devtools/split-debug.sh],[chmod +x contrib/devtools/split-debug.sh])
 AM_COND_IF([HAVE_DOXYGEN], [AC_CONFIG_FILES([doc/Doxyfile])])
diff --git a/doc/README.md b/doc/README.md
index 19d8204d83..f32600d009 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -44,6 +44,7 @@ The following are developer notes on how to build Bitcoin Core on your native pl
 - [FreeBSD Build Notes](build-freebsd.md)
 - [OpenBSD Build Notes](build-openbsd.md)
 - [NetBSD Build Notes](build-netbsd.md)
+- [Android Build Notes](build-android.md)
 - [Gitian Building Guide (External Link)](https://github.com/bitcoin-core/docs/blob/master/gitian-building.md)
 
 Development
diff --git a/doc/build-android.md b/doc/build-android.md
new file mode 100644
index 0000000000..7a8a9e6a65
--- /dev/null
+++ b/doc/build-android.md
@@ -0,0 +1,12 @@
+ANDROID BUILD NOTES
+======================
+
+This guide describes how to build and package the `bitcoin-qt` GUI for Android on Linux and macOS.
+
+## Preparation
+
+You will need to get the Android NDK and build dependencies for Android as described in [depends/README.md](../depends/README.md).
+
+## Building and packaging
+
+After the depends are built configure with one of the resulting prefixes and run `make && make apk` in `src/qt`.
\ No newline at end of file
diff --git a/src/Makefile.qt.include b/src/Makefile.qt.include
index 59cfdb9839..399a8430ef 100644
--- a/src/Makefile.qt.include
+++ b/src/Makefile.qt.include
@@ -378,6 +378,20 @@ bitcoin_qt_clean: FORCE
 
 bitcoin_qt : qt/bitcoin-qt$(EXEEXT)
 
+APK_LIB_DIR = qt/android/libs/$(ANDROID_ARCH)
+QT_BASE_PATH = $(shell find ../depends/sources/ -maxdepth 1 -type f -regex ".*qtbase.*\.tar.xz")
+QT_BASE_TLD = $(shell tar tf $(QT_BASE_PATH) --exclude='*/*')
+
+bitcoin_qt_apk: FORCE
+	mkdir -p $(APK_LIB_DIR)
+	cp $(dir $(CC))../sysroot/usr/lib/$(host_alias)/libc++_shared.so $(APK_LIB_DIR)
+	tar xf $(QT_BASE_PATH) -C qt/android/src/ $(QT_BASE_TLD)src/android/jar/src --strip-components=5
+	tar xf $(QT_BASE_PATH) -C qt/android/src/ $(QT_BASE_TLD)src/android/java/src --strip-components=5
+	tar xf $(QT_BASE_PATH) -C qt/android/res/ $(QT_BASE_TLD)src/android/java/res --strip-components=5
+	cp qt/bitcoin-qt $(APK_LIB_DIR)/libbitcoin-qt.so
+	cd qt/android && gradle wrapper --gradle-version=6.6.1
+	cd qt/android && ./gradlew build
+
 ui_%.h: %.ui
 	@test -f $(UIC)
 	@$(MKDIR_P) $(@D)
diff --git a/src/qt/Makefile b/src/qt/Makefile
index b9dcf0c599..3bd6199059 100644
--- a/src/qt/Makefile
+++ b/src/qt/Makefile
@@ -7,3 +7,5 @@ check: FORCE
 	$(MAKE) -C .. test_bitcoin_qt_check
 bitcoin-qt bitcoin-qt.exe: FORCE
 	 $(MAKE) -C .. bitcoin_qt
+apk: FORCE
+	$(MAKE) -C .. bitcoin_qt_apk
diff --git a/src/qt/android/AndroidManifest.xml b/src/qt/android/AndroidManifest.xml
new file mode 100644
index 0000000000..abb88fe89d
--- /dev/null
+++ b/src/qt/android/AndroidManifest.xml
@@ -0,0 +1,38 @@
+<?xml version='1.0' encoding='utf-8'?>
+<manifest package="org.bitcoincore.qt" xmlns:android="http://schemas.android.com/apk/res/android" android:versionName="1.0" android:versionCode="1" android:installLocation="auto">
+    <uses-sdk android:targetSdkVersion="24"/>
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+
+    <uses-feature android:glEsVersion="0x00020000" android:required="true" />
+
+    <supports-screens android:largeScreens="true" android:normalScreens="true" android:anyDensity="true" android:smallScreens="true"/>
+
+    <application android:hardwareAccelerated="true" android:name="org.qtproject.qt5.android.bindings.QtApplication" android:label="Bitcoin Core">
+        <activity android:configChanges="orientation|uiMode|screenLayout|screenSize|smallestScreenSize|layoutDirection|locale|fontScale|keyboard|keyboardHidden|navigation|mcc|mnc|density"
+                  android:name="org.bitcoincore.qt.BitcoinQtActivity"
+                  android:label="Bitcoin Core"
+                  android:icon="@drawable/bitcoin"
+                  android:screenOrientation="unspecified"
+                  android:launchMode="singleTop">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+
+            <meta-data android:name="android.app.arguments" android:value="-testnet"/>
+            <meta-data android:name="android.app.lib_name" android:value="bitcoin-qt"/>
+            <meta-data android:name="android.app.repository" android:value="default"/>
+            <meta-data android:name="android.app.bundle_local_qt_libs" android:value="1"/>
+            <meta-data android:name="android.app.use_local_qt_libs" android:value="1"/>
+            <meta-data android:name="android.app.libs_prefix" android:value="/data/local/tmp/qt/"/>
+            <meta-data android:name="android.app.system_libs_prefix" android:value="/system/lib/"/>
+            <meta-data android:name="android.app.background_running" android:value="true"/>
+            <meta-data android:name="android.app.auto_screen_scale_factor" android:value="true"/>
+            <meta-data android:name="android.app.extract_android_style" android:value="default"/>
+    </activity>
+
+    </application>
+</manifest>
diff --git a/src/qt/android/build.gradle b/src/qt/android/build.gradle
new file mode 100644
index 0000000000..4c36e79db8
--- /dev/null
+++ b/src/qt/android/build.gradle
@@ -0,0 +1,52 @@
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.1.0'
+    }
+}
+
+repositories {
+    google()
+    jcenter()
+}
+
+apply plugin: 'com.android.application'
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+}
+
+android {
+    compileSdkVersion androidCompileSdkVersion.toInteger()
+
+    buildToolsVersion androidBuildToolsVersion
+
+    sourceSets {
+        main {
+            manifest.srcFile 'AndroidManifest.xml'
+            java.srcDirs = [qt5AndroidDir + '/src', 'src', 'java']
+            aidl.srcDirs = [qt5AndroidDir + '/src', 'src', 'aidl']
+            res.srcDirs = [qt5AndroidDir + '/res', 'res']
+            resources.srcDirs = ['src']
+            renderscript.srcDirs = ['src']
+            assets.srcDirs = ['assets']
+            jniLibs.srcDirs = ['libs']
+       }
+    }
+
+    lintOptions {
+        abortOnError false
+    }
+
+    dexOptions {
+        javaMaxHeapSize '4g'
+    }
+
+    defaultConfig {
+        minSdkVersion 24
+    }
+}
diff --git a/src/qt/android/gradle.properties b/src/qt/android/gradle.properties
new file mode 100644
index 0000000000..838870f62d
--- /dev/null
+++ b/src/qt/android/gradle.properties
@@ -0,0 +1,4 @@
+androidBuildToolsVersion=28.0.3
+androidCompileSdkVersion=28
+qt5AndroidDir=new File(".").absolutePath
+org.gradle.jvmargs=-Xmx4608M
diff --git a/src/qt/android/res/drawable-hdpi/bitcoin.png b/src/qt/android/res/drawable-hdpi/bitcoin.png
new file mode 100644
index 0000000000..31a556a35f
--- /dev/null
+++ b/src/qt/android/res/drawable-hdpi/bitcoin.png
diff --git a/src/qt/android/res/drawable-ldpi/bitcoin.png b/src/qt/android/res/drawable-ldpi/bitcoin.png
new file mode 100644
index 0000000000..76d80d4196
--- /dev/null
+++ b/src/qt/android/res/drawable-ldpi/bitcoin.png
diff --git a/src/qt/android/res/drawable-mdpi/bitcoin.png b/src/qt/android/res/drawable-mdpi/bitcoin.png
new file mode 100644
index 0000000000..c2aeab851a
--- /dev/null
+++ b/src/qt/android/res/drawable-mdpi/bitcoin.png
diff --git a/src/qt/android/res/drawable-xhdpi/bitcoin.png b/src/qt/android/res/drawable-xhdpi/bitcoin.png
new file mode 100644
index 0000000000..2bd5e3defc
--- /dev/null
+++ b/src/qt/android/res/drawable-xhdpi/bitcoin.png
diff --git a/src/qt/android/res/drawable-xxhdpi/bitcoin.png b/src/qt/android/res/drawable-xxhdpi/bitcoin.png
new file mode 100644
index 0000000000..d236cf2132
--- /dev/null
+++ b/src/qt/android/res/drawable-xxhdpi/bitcoin.png
diff --git a/src/qt/android/res/drawable-xxxhdpi/bitcoin.png b/src/qt/android/res/drawable-xxxhdpi/bitcoin.png
new file mode 100644
index 0000000000..bb1dbc3554
--- /dev/null
+++ b/src/qt/android/res/drawable-xxxhdpi/bitcoin.png
diff --git a/src/qt/android/src/org/bitcoincore/qt/BitcoinQtActivity.java b/src/qt/android/src/org/bitcoincore/qt/BitcoinQtActivity.java
new file mode 100644
index 0000000000..cf3b4f6668
--- /dev/null
+++ b/src/qt/android/src/org/bitcoincore/qt/BitcoinQtActivity.java
@@ -0,0 +1,29 @@
+package org.bitcoincore.qt;
+
+import android.os.Bundle;
+import android.system.ErrnoException;
+import android.system.Os;
+
+import org.qtproject.qt5.android.bindings.QtActivity;
+
+import java.io.File;
+
+public class BitcoinQtActivity extends QtActivity
+{
+    @Override
+    public void onCreate(Bundle savedInstanceState)
+    {
+        final File bitcoinDir = new File(getFilesDir().getAbsolutePath() + "/.bitcoin");
+        if (!bitcoinDir.exists()) {
+            bitcoinDir.mkdir();
+        }
+
+        try {
+            Os.setenv("QT_QPA_PLATFORM", "android", true);
+        } catch (ErrnoException e) {
+            e.printStackTrace();
+        }
+
+        super.onCreate(savedInstanceState);
+    }
+}
diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
index 791a29f7a0..fc6d0febc2 100644
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -466,6 +466,12 @@ int GuiMain(int argc, char* argv[])
     QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
     QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
 
+#if defined(QT_QPA_PLATFORM_ANDROID)
+    QApplication::setAttribute(Qt::AA_DontUseNativeMenuBar);
+    QApplication::setAttribute(Qt::AA_DontCreateNativeWidgetSiblings);
+    QApplication::setAttribute(Qt::AA_DontUseNativeDialogs);
+#endif
+
     BitcoinApplication app;
     QFontDatabase::addApplicationFont(":/fonts/monospace");