13. June 2018

Android Studio NDK could not start mips64el-linux-android-strip

If you’re using Android Studio to build C++ application with NDK you might encounter following error during build:

org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformNativeLibsWithStripDebugSymbolForDebug'.
...
Caused by: java.io.IOException: Cannot run program ".../Android/Sdk/ndk-bundle/toolchains/mips64el-linux-android-4.9/prebuilt/linux-x86_64/bin/mips64el-linux-android-strip": 
error=2, No such file or directory

The problem is caused by the upgrade of NDK in Android Studio to NDK v17. This version has a different structure of tools. It’s not compatible with Android Experimental Plugin v0.11.

The directory which should contain binary of tools contains just file NOTICE-MIPS64:

This mips64el-linux-android-4.9 directory exists to make the NDK compatible with the Android
SDK's Gradle plugin, version 3.0.1 and earlier, which expects the NDK
to have a MIPS64 toolchain directory.

The solution is to download NDK v16 from NDK older releases. Extract it and replace former ndk-bundle directory.

Commands for macOS or Linux users:

cd ~/Android
unzip ~/Downloads/android-ndk-r16b-linux-x86_64.zip
mv ndk-bundle ndk-bundle-v17
mv android-ndk-r16b ndk-bundle

If you’re Windows user the location of NDK is typically in your profile AppData\Local\Android. Do not forget to unblock the ZIP after downloading (right click, Properties, Unblock, Ok)

Commands for Windows users:

cd ~\AppData\Local\Android
unzip ~\Downloads\android-ndk-r16b-windows-x86_64.zip
mv ndk-bundle ndk-bundle-v17
mv android-ndk-r16b ndk-bundle

Start Android Studio. It should prompt you to update NDK. Do not confirm this request, it will replace NDK with v17. You should see the following screen in SDK Manager:

You can find related sample source code at GitHub in sdl2-android-example repository. Further articles about SDL2 and Android are available under the tag SDL2.

10. May 2018

SDL2_gfx for Android – Graphic primitives

In previous article, we were talking about drawing pictures in JPEG format. Let’s look how to draw some graphic primitives like a line. SDL2_gfx is small library which has support for graphic primitives and some surface functions.

The initial steps to add SDL2_gfx to Android project is the same like in case of SDL2_jpeg.

Register library in settings.gradle:

include ':SDL2_gfx'

The library should be stored in SDL2_gfx directory with build.gradle.

Now update our C application.

Here is simple example which draws a line:

thickLineColor(renderer, 0, 300, 300, 300, 20, 0xFF00FFFF);

You can find the source code at GitHub in sdl2-android-example repository. Further articles about SDL2 and android are available under the tag SDL2.

Special thanks for this extension of SDL2 Android example goes to jojomickymack who suggested how to add support for SDL2_gfx to Android project. Thank you.

1. October 2017

Missing Run or Debug action in Android Studio with Gradle project

Imagine the simple situation. You want to open an Android project in Android Studio.

Click File, Open. Find the project and click Ok.

Android Studio will open the project. Gradle seems to be working, but there is no Run or Debug action.

Android Studio does not provide any hint where is the issue.

The solution is simple. One important file is missing: settings.gradle. The file defines which modules should be included during the build.

To fix the issue just create settings.gradle in the root of your project:

include ':app'

Click Sync Gradle and within few moments you should be able to run the application.

If your application contains more modules, you can specify them in a similar way like in sdl2-android-example/settings.gradle.

23. September 2017

SDL2_ttf for Android with TrueType font support

Common library for displaying a text in SDL2 application is SDL2_ttf. The library is a wrapper on FreeType library. It is necessary to add both libraries into a project.

Let’s start with FreeType dependency. Add build.gradle file. Just be aware that there will be many excluded files. The library itself is very huge, and only a fraction of functions is necessary for the application.

...
sources {
      main {
          jni {
              source {
                  srcDir "src"
                  exclude "autofit"
                  exclude "smooth/smooth.c"
...
                   // Including this file in build causes duplications, because it includes directly C files
                   exclude "truetype/truetype.c"
                   exclude "type1"
                   exclude "type42"
                   exclude "winfonts"
              }
          }
      }
}

Adding SDL2_ttf is similar to other libraries like SDL2_jpeg or SDL2_mixer.

SDL2_ttf and FreeType modules should be also registered at settings.gradle:

include ':freetype'
...
include ':SDL2_ttf'

The first step to displaying text on the screen is to initialize the library and load a font:

#include "SDL_ttf.h"
...    
if (TTF_Init() == -1) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "TTF_Init: %s\n", TTF_GetError());
    return 7;
}

The next step is to load a font. The file should be stored in app/src/main/assets.

TTF_Font *font = TTF_OpenFont("blazed.ttf", 32);
if (!font) {
    SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
                 "Unable to load font: %s\n", TTF_GetError());
    return 8;
}

The next step is to render a text:

SDL_Color textColor = { 255, 240, 0, 255 };
SDL_Surface* solid = TTF_RenderText_Solid(font, "SDL2 Android Example", textColor);

SDL_Texture* solidTexture = SDL_CreateTextureFromSurface(renderer, solid);
SDL_RenderCopy(renderer, solidTexture, NULL, &dstrect);
SDL_FreeSurface(solid);

Here is the result:

You can find the source code at GitHub in sdl2-android-example repository. Further articles about SDL2 and Android are available under the tag SDL2.

13. September 2017

SDL2_mixer for Android playing WAV file

In previous articles, we were talking about PNG and JPEG support in SDL2 for Android. Let’s add some sounds to our application.

The initial steps are same as in case of SDL2_image.

Register library in settings.gradle:

include ':SDL2_mixer'

The library should be stored in SDL2_mixer directory with build.gradle that written in style for a library.

Now update our C application.

First of all, it is necessary to initialize the library. Then it is possible to load the sound file.

    if (Mix_OpenAudio(22050, MIX_DEFAULT_FORMAT, 2, 4096) == -1 ) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
                     "Couldn't open mixer: %s", SDL_GetError());
        return 2;
    }
    Mix_Chunk *sample = Mix_LoadWAV("cuckoo.wav");
    if (sample == NULL) {
        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, 
                     "Unable to load wave file\n");
        return 3;
    }

The file WAV should be stored in app/src/main/assets. Just small reminder: this is just a virtual directory, and you won’t be able to access it from other application on Android.

Playing the sound is simple:

Mix_PlayChannel(-1, sample, 0);

The last important thing about SDL2_mixer is that you should close SDL2_mixer when exiting the main. Otherwise, when you relaunch SDLActivity, it won’t be able to play any sound.

Mix_CloseAudio();

You can find the source code at GitHub in sdl2-android-example repository. Further articles about SDL2 and android are available under the tag SDL2.

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