Add CDep Dependencies to an Existing Android Studio CMake Project

This tutorial will show you how to add the first CDep dependency to an existing Android Studio project. If you'd rather just see a finished example of this then check out CDep Freetype Sample.

This tutorial was tested on Ubuntu but should work on MacOS and Windows. Any changes needed will be noted.

Setup

This step creates a new Android Studio CMake project to use in this tutorial. If you already have a project to use then you can skip it.

Follow these steps:

1. Start Android Studio 2.2 or later
2. File->New->New project...
3. Click Include C++ Support checkbox
4. Next, next
5. Choose Empty Activity
6. Next, next, finish

Step 1 -- Clone the cdep-redist project

At this point you should have a project open in Android Studio. Open a terminal window by clicking Terminal. It is usually in the lower part of Android Studio.

In the terminal, clone the cdep redist project.

pushd ..
git clone https://github.com/jomof/cdep-redist.git
popd

The folder you choose to clone into doesn't really matter. This tutorial places it in the folder next to the Android Studio project we're working on.

Step 2 -- Add the CDep wrapper to the Android Studio project

../cdep-redist/cdep wrapper

If this was successful then you should see output like this.

Installing ./cdep.bat
Installing ./cdep
Installing ./bootstrap/wrapper/bootstrap.jar
Installing ./cdep.yml

These four files form the CDep 'wrapper'. The files are very small and are meant to be checked in to source control. Briefly, this is the purpose of each file.

• cdep.bat is the cdep wrapper that will run on Windows
• cdep is the cdep wrapper script that will run on Linux and MacOS
• bootstrap/wrapper/bootstrap.jar is a small executable that has a function to download the main cdep executable
• cdep.yml is where you place references to CDep packages

Step 3 -- Add a reference to SQLite in cdep.yml

Open cdep.yml in Android Studio and replace the existing text there with the following.

builders: [cmake]

dependencies:
- compile: com.github.jomof:sqlite:3.16.2-rev51

This tells CDep two things:

1. This is a CMake project so generate CMake glue code for the modules
2. This project references SQLite

Step 4 -- Use CDep to generate CMake glue code for SQLite

./cdep

or on Windows,

cdep

If this worked you should see a message like this.

Downloading https://github.com/jomof/sqlite/releases/download/3.16.2-rev51/cdep-manifest.yml
Generating .cdep/modules/cdep-dependencies-config.cmake

At this point, CDep has only downloaded the package manifest. The parts of the package needed to build will be downloaded on demand.

Step 5 -- Reduce ABIs built to those that SQLite supports

Most CDep packages, including SQLite, don't support mips and mips64. However, some versions of Android Studio still build those ABIs by default. Let's reduce the set of ABIs. Open the file app/build.gradle in Android Studio (not the root build.gradle). Add the following to defaultConfig`.

defaultConfig{
    ndk {
        abiFilters "x86", "x86_64", "armeabi-v7a", "armeabi", "arm64-v8a"
    }
}

Step 6 -- Modify the CMake arguments to tell CMake where to find the module glue

Now add the following lines to the same defaultConfig section.

defaultConfig {
    externalNativeBuild {
        cmake {
            arguments "-Dcdep-dependencies_DIR=../.cdep/modules"
        }
    }
}

After this, Android Studio may prompt you to sync. Don't worry about this yet because we're still making changes. It's okay to sync if you want to get rid of the banner message.

Step 7 -- Modify CMakeLists.txt to add CDep dependencies to native-lib target

Now open CMakeLists.txt and add the following code at the end of the file.

find_package(cdep-dependencies REQUIRED)
add_all_cdep_dependencies(native-lib)

This tells CMake to locate the module glue file and then to add all the dependencies in that file to the native-lib target.

Step 8 -- Modify native-lib.cpp to actually use SQLite

Open up native-lib.cpp in Android Studio and replace the text there with the following

#include <jni.h>
#include <string>
#include <sqlite3.h>

extern "C"
JNIEXPORT jstring JNICALL
Java_com_example_jomof_myapplication_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    sqlite3_initialize();
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

Step 9 -- Build the project

In Android Studio do Build->Rebuild Project. If everything above worked, the project should build with no errors.

Congratulations!

You have a project with a working CDep dependency. Most of the steps above are only needed the first time. To add the next CDep dependency just edit cdep.yml and then re-run cdep from the command-line.