README.android
author Sam Lantinga <slouken@libsdl.org>
Wed, 12 Jan 2011 12:40:11 -0800
changeset 4976 3811132c584f
parent 4975 6fbc7044f343
child 6273 2fa7e0540f95
permissions -rw-r--r--
Added information about starting a command shell on the device
     1 ================================================================================
     2 Simple DirectMedia Layer for Android
     3 ================================================================================
     4 
     5 Requirements:
     6 
     7 Android SDK
     8 http://developer.android.com/sdk/index.html
     9 
    10 Android NDK r4 or later
    11 http://developer.android.com/sdk/ndk/index.html
    12 
    13 
    14 ================================================================================
    15  How the port works
    16 ================================================================================
    17 
    18 - Android applications are Java-based, optionally with parts written in C
    19 - As SDL apps are C-based, we use a small Java shim that uses JNI to talk to 
    20 the SDL library
    21 - This means that your application C code must be placed inside an android 
    22 Java project, along with some C support code that communicates with Java
    23 - This eventually produces a standard Android .apk package
    24 
    25 The Android Java code implements an "activity" and can be found in:
    26 android-project/src/org/libsdl/app/SDLActivity.java
    27 
    28 The Java code loads your game code, the SDL shared library, and
    29 dispatches to native functions implemented in the SDL library:
    30 src/SDL_android.cpp
    31 
    32 Your project must include some glue code that starts your main() routine:
    33 src/main/android/SDL_android_main.cpp
    34 
    35 
    36 ================================================================================
    37  Building an app
    38 ================================================================================
    39 
    40 Instructions:
    41 1. Copy the android-project directory wherever you want to keep your projects and rename it to the name of your project.
    42 2. Move this SDL directory into the <project>/jni directory
    43 3. Place your application source files in the <project>/jni/src directory
    44 4. Edit <project>/jni/src/Android.mk to include your source files
    45 5. Run 'ndk-build' (a script provided by the NDK). This compiles the C source
    46 
    47 If you want to use the Eclipse IDE, skip to the Eclipse section below.
    48 
    49 6. Edit <project>/local.properties to point to the Android SDK directory
    50 7. Run 'ant debug' in android/project. This compiles the .java and eventually 
    51 creates a .apk with the native code embedded
    52 8. 'ant install' will push the apk to the device or emulator (if connected)
    53 
    54 Here's an explanation of the files in the Android project, so you can customize them:
    55 
    56 android-project/
    57 	AndroidManifest.xml	- package manifest, do not modify
    58 	build.properties	- empty
    59 	build.xml		- build description file, used by ant
    60 	default.properties	- holds the ABI for the application, currently android-4 which corresponds to the Android 1.6 system image
    61 	local.properties	- holds the SDK path, you should change this to the path to your SDK
    62 	jni/			- directory holding native code
    63 	jni/Android.mk		- Android makefile that includes all subdirectories
    64 	jni/SDL/		- directory holding the SDL library files
    65 	jni/SDL/Android.mk	- Android makefile for creating the SDL shared library
    66 	jni/src/		- directory holding your C/C++ source
    67 	jni/src/Android.mk	- Android makefile that you should customize to include your source code and any library references
    68 	res/			- directory holding resources for your application
    69 	res/drawable-*		- directories holding icons for different phone hardware
    70 	res/layout/main.xml	- place holder for the main screen layout, overridden by the SDL video output
    71 	res/values/strings.xml	- strings used in your application, including the application name shown on the phone.
    72 	src/org/libsdl/app/SDLActivity.java	- the Java class handling the initialization and binding to SDL.  Be very careful changing this, as the SDL library relies on this implementation.
    73 
    74 
    75 ================================================================================
    76  Additional documentation
    77 ================================================================================
    78 
    79 The documentation in the NDK docs directory is very helpful in understanding the build process and how to work with native code on the Android platform.
    80 
    81 The best place to start is with docs/OVERVIEW.TXT
    82 
    83 
    84 ================================================================================
    85  Using Eclipse
    86 ================================================================================
    87 
    88 First make sure that you've installed Eclipse and the Android extensions as described here:
    89 	http://developer.android.com/sdk/eclipse-adt.html
    90 
    91 Once you've copied the SDL android project and customized it, you can create an Eclipse project from it:
    92  * File -> New -> Other
    93  * Select the Android -> Android Project wizard and click Next
    94  * Enter the name you'd like your project to have
    95  * Select "Create project from existing source" and browse for your project directory
    96  * Make sure the Build Target is set to Android 1.6
    97  * Click Finish
    98 
    99 
   100 ================================================================================
   101  Loading files and resources
   102 ================================================================================
   103 
   104 NEED CONTENT
   105 
   106 
   107 ================================================================================
   108  Troubleshooting
   109 ================================================================================
   110 
   111 You can create and run an emulator from the Eclipse IDE:
   112  * Window -> Android SDK and AVD Manager
   113 
   114 You can see if adb can see any devices with the following command:
   115 	adb devices
   116 
   117 You can see the output of log messages on the default device with:
   118 	adb logcat
   119 
   120 You can push files to the device with:
   121 	adb push local_file remote_path_and_file
   122 
   123 You can push files to the SD Card at /sdcard, for example:
   124 	adb push moose.dat /sdcard/moose.dat
   125 
   126 You can see the files on the SD card with a shell command:
   127 	adb shell ls /sdcard/
   128 
   129 You can start a command shell on the default device with:
   130 	adb shell
   131 
   132 You can do a clean build with the following commands:
   133 	ndk-build clean
   134 	ndk-build
   135 
   136 You can see the complete command line that ndk-build is using by passing V=1 on the command line:
   137 	ndk-build V=1
   138 
   139 If your application crashes in native code, you can use addr2line to convert the addresses in the stack trace to lines in your code.
   140 
   141 For example, if your crash looks like this:
   142 I/DEBUG   (   31): signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 400085d0
   143 I/DEBUG   (   31):  r0 00000000  r1 00001000  r2 00000003  r3 400085d4
   144 I/DEBUG   (   31):  r4 400085d0  r5 40008000  r6 afd41504  r7 436c6a7c
   145 I/DEBUG   (   31):  r8 436c6b30  r9 435c6fb0  10 435c6f9c  fp 4168d82c
   146 I/DEBUG   (   31):  ip 8346aff0  sp 436c6a60  lr afd1c8ff  pc afd1c902  cpsr 60000030
   147 I/DEBUG   (   31):          #00  pc 0001c902  /system/lib/libc.so
   148 I/DEBUG   (   31):          #01  pc 0001ccf6  /system/lib/libc.so
   149 I/DEBUG   (   31):          #02  pc 000014bc  /data/data/org.libsdl.app/lib/libmain.so
   150 I/DEBUG   (   31):          #03  pc 00001506  /data/data/org.libsdl.app/lib/libmain.so
   151 
   152 You can see that there's a crash in the C library being called from the main code.  I run addr2line with the debug version of my code:
   153 	arm-eabi-addr2line -C -f -e obj/local/armeabi/libmain.so
   154 and then paste in the number after "pc" in the call stack, from the line that I care about:
   155 000014bc
   156 
   157 I get output from addr2line showing that it's in the quit function, in testspriteminimal.c, on line 23.
   158 
   159 You can add logging to your code to help show what's happening:
   160 
   161 #include <android/log.h>
   162 
   163 	__android_log_print(ANDROID_LOG_INFO, "foo", "Something happened! x = %d", x);
   164 
   165 If you need to build without optimization turned on, you can create a file called "Application.mk" in the jni directory, with the following line in it:
   166 APP_OPTIM := debug
   167 
   168 
   169 ================================================================================
   170  Known issues
   171 ================================================================================
   172 
   173 - SDL audio (although it's mostly written, just not working properly yet)
   174 - TODO. I'm sure there's a bunch more stuff I haven't thought of