Synopsis

Simple RPI cam viewer for Android meant to be used in conjunction with the minimal rpi cam server.

Note: this was originally written in 2017 and has since been revisited.

Requirements

• Android SDK (used 24, 26)
• Android NDK
• Qt (tried with 5.6+)
• openjdk 1.8
• openjdk-devel
• Android platform API (24)
• Apache ANT 1.10.1
• Gradle (auto downloaded by androiddeployqt)
• C++11+ compliant compiler

See android sdk, ndk, and Qt section for notes on installing Android sdk/ndk and QT.

Usage

Compile and run the executable. Enter the server information in the fields:

• host: Use either IP address of the host, or a URL of the host. If only an IP address is specified, defaults to HTTP and periodic image updates. If websocket protocol is specified e.g. ws://<ip-address>, streams video
• username: username for HTTP access
• password: password for HTTP access
• WS Token: authentication token sent to server on first connect to websocket. Only used when using the websocket protocol.

Compilation

First, download and install QT and Android SDK and NDK. Then follow sections below.

Android (x86)

1. Adjust paths under env.sh
2. Run android_build.sh

Note:

• if running for the first time and gradle does not exist on system path, then androiddeployqt will silently download gradle to ~/.gradle. It's a larger file so may take a while.

Android (arm)

1. Adjust paths under env.sh
2. Modify android_build.sh and change relevant entries to armv7
3. Run android_build.sh

iOS

TODO

Desktop (x86)

source env.sh gcc_64
qmake64
make clean
make

Deploy to Android emulator

Start emulator, then push to device.

emulator -avd created-device-name -skin 540x960 # (or e.g. 1200x1920)
adb install -r PATH/TO/APK

Getting started with Android and AVD

There were a lot of bugs originally when using Qt 5.6.2 e.g. blank screen when starting apps in the android emulator.

1. Download the Android SDK

Only downloaded command-line tools (147MB zipped)

curl -O https://dl.google.com/android/repository/sdk-tools-linux-4333796.zip
unzip sdk-tools-linux-4333796.zip # unzips to `tool`
mkdir /opt/android/
mv tool /opt/android/sdk/

2. Download the Android NDK

Direct download:

curl -O https://dl.google.com/android/repository/android-ndk-r19c-linux-x86_64.zip
unzip android-ndk-r19c-linux-x86_64.zip
mkdir /opt/android/ndk
mv android-ndk-r19c /opt/android/ndk

3. Download Qt (e.g. 5.12)

download-qt5.12.2-from-website # .run file
chmod u+x qt5.12.2.run
./qt5.12.2.run
mv-extracted-contents-to /opt/Qt/5.12.2

4. Install prerequisites

On OpenSUSE,

zypper in java-1_8_0-openjdk java-1_8_0-openjdk-devel

5. Create and/or download Android images and tools

• Download platform-tools, emulator, and system images

sdkmanager --list
sdkmanager "platform-tools" "platforms;android-25"
# Download system image files -- it's a big file, might take a while
sdkmanager "system-images;android-25;google_apis;x86"
sdkmanager "emulator"

• Create an android virtual device

avdmanager create avd \
    -name "insert-device-name-here-with-quotes" \
    --path path/to/device-image \
    -k "image-name"

where image-name may be e.g. "system-images;android-25;google_apis;x86"

Test emulator

emulator -avd created-device-name -skin 540x960 # (or e.g. 1200x1920)

Add keyboard support to the virtual device.

echo "hw.keyboard=yes" >> /path/to/device-avd-directory/config.ini
# E.g. path `~/.android/avd/mydevice.avd/config.ini`

6. Build QT application

Originally I tried using cmake but was greeted with a continuous influx of errors which seemed to emanate from bugs and version incompatiblities. After the 8th hour I gave up and settled for qmake. It is possible that all the issues are fixed in the latest versions of the toolkits, but I never revisited it.

Latest toolkits doesn't seem to work with ant anymore and must use gradle instead.

qmake # (armv7, x86, etc depending on target platform)
BUILD_DIR=/some/path/for/build/directory
make
# will auto create directory if nonexistent
make install INSTALL_ROOT=$BUILD_DIR
androiddeployqt --output $BUILD_DIR \
    --input /path/to/qmake-json-output-file.json \
    --android-platform $ANDROID_API_PLATOFRM \
    --verbose \
    --gradle

Look under ANDROID_NDK_ROOT/platforms for valid $ANDROID_API_PLATORM.

E.g.

qtdeploy_x86 --output ./build_and86/ \
   --input android-librpicamview.so-deployment-settings.json \
   --android-platform android-24 \
   --verbose \
   --gradle

If running for the first time, it will download and extract gradle to ~/.gradle (but for some reason it won't explicitly tell you this)

Note: this build process is simplified with the android build script file.

Pushing apks to emulator while the emulator is running:

adb install -r PATH/TO/file.apk

TODO

• Better streamline builds for different platforms