2 ================================================================================
4 Matt Styles wrote
a tutorial on building SDL
for Android with Visual Studio:
7 The rest of
this README covers the old style build process.
9 ================================================================================
11 ================================================================================
13 Android SDK (version 16 or later)
16 Android NDK r7 or later
19 Minimum API
level supported
by SDL: 10 (Android 2.3.3)
22 ================================================================================
24 ================================================================================
26 - Android applications are Java-based, optionally with parts written
in C
27 - As SDL apps are C-based, we use
a small Java shim that uses JNI to talk to
29 - This means that your application C code must be placed inside an Android
30 Java project, along with some C support code that communicates with Java
31 - This eventually produces
a standard Android .apk package
33 The Android Java code implements an
"Activity" and can be found
in:
34 android-project/
src/org/libsdl/app/SDLActivity.java
36 The Java code loads your game code, the SDL shared library, and
37 dispatches to native functions implemented
in the SDL library:
38 src/core/android/SDL_android.c
40 Your project must include some glue code that starts your
main() routine:
41 src/
main/android/SDL_android_main.c
44 ================================================================================
46 ================================================================================
48 For simple projects you can use the script located at build-scripts/androidbuild.sh
50 There
's two ways of using it:
52 androidbuild.sh com.yourcompany.yourapp < sources.list
53 androidbuild.sh com.yourcompany.yourapp source1.c source2.c ...sourceN.c
55 sources.list should be a text file with a source file name in each line
56 Filenames should be specified relative to the current directory, for example if
57 you are in the build-scripts directory and want to create the testgles.c test, you'll
60 ./androidbuild.sh org.libsdl.testgles ../test/testgles.c
62 One limitation of
this script is that all
sources provided will be aggregated into
63 a single directory, thus all your
source files should have
a unique
name.
65 Once the project is complete the script will tell you where the debug APK is located.
66 If you want to create
a signed release APK, you can use the project created
by this
67 utility to generate it.
69 Finally,
a word of caution: re running androidbuild.sh wipes any changes you may have
70 done in the build directory
for the app!
73 For more complex projects, follow these instructions:
75 1. Copy the android-project directory wherever you want to keep your projects
76 and rename it to the
name of your project.
77 2. Move or symlink
this SDL directory into the
"<project>/jni" directory
78 3. Edit
"<project>/jni/src/Android.mk" to include your
source files
79 4.
Run 'ndk-build' (
a script provided
by the NDK). This compiles the C
source
81 If you want to use the Eclipse IDE, skip to the Eclipse section below.
83 5. Create
"<project>/local.properties" and use that to point to the Android SDK directory,
by writing
a line with the following form:
85 sdk.dir=PATH_TO_ANDROID_SDK
87 6.
Run 'ant debug' in android/project. This compiles the .java and eventually
88 creates
a .apk with the native code embedded
89 7.
'ant debug install' will push the apk to the
device or emulator (
if connected)
91 Here
's an explanation of the files in the Android project, so you can customize them:
94 AndroidManifest.xml - package manifest. Among others, it contains the class name
95 of the main Activity and the package name of the application.
96 build.properties - empty
97 build.xml - build description file, used by ant. The actual application name
99 default.properties - holds the target ABI for the application, android-10 and up
100 project.properties - holds the target ABI for the application, android-10 and up
101 local.properties - holds the SDK path, you should change this to the path to your SDK
102 jni/ - directory holding native code
103 jni/Android.mk - Android makefile that can call recursively the Android.mk files
104 in all subdirectories
105 jni/SDL/ - (symlink to) directory holding the SDL library files
106 jni/SDL/Android.mk - Android makefile for creating the SDL shared library
107 jni/src/ - directory holding your C/C++ source
108 jni/src/Android.mk - Android makefile that you should customize to include your
109 source code and any library references
110 res/ - directory holding resources for your application
111 res/drawable-* - directories holding icons for different phone hardware. Could be
112 one dir called "drawable".
113 res/layout/main.xml - Usually contains a file main.xml, which declares the screen layout.
114 We don't need it because we use the SDL video
output.
117 src/org/libsdl/app/SDLActivity.java - the Java
class handling the initialization and binding
118 to SDL. Be very careful changing this, as the SDL library relies
119 on this implementation.
122 ================================================================================
123 Build an app with
static linking of libSDL
124 ================================================================================
126 This build uses the Android NDK module system.
129 1. Copy the android-project directory wherever you want to keep your projects
130 and rename it to the
name of your project.
131 2. Rename
"<project>/jni/src/Android_static.mk" to
"<project>/jni/src/Android.mk"
132 (overwrite the existing
one)
133 3. Edit
"<project>/jni/src/Android.mk" to include your
source files
134 4. create and export an environment
variable named NDK_MODULE_PATH that
points
135 to the parent directory of
this SDL directory.
e.g.:
137 export NDK_MODULE_PATH=
"$PWD"/..
139 5. Edit
"<project>/src/org/libsdl/app/SDLActivity.java" and
remove the call to
140 System.loadLibrary(
"SDL2").
141 6.
Run 'ndk-build' (
a script provided
by the NDK). This compiles the C
source
144 ================================================================================
145 Customizing your application
name
146 ================================================================================
148 To customize your application
name, edit AndroidManifest.xml and replace
149 "org.libsdl.app" with an identifier
for your product package.
151 Then create
a Java
class extending SDLActivity and place it
in a directory
152 under
src matching your package,
e.g.
154 src/com/gamemaker/game/MyGame.java
156 Here
's an example of a minimal class file:
158 --- MyGame.java --------------------------
159 package com.gamemaker.game;
161 import org.libsdl.app.SDLActivity;
167 public class MyGame extends SDLActivity { }
169 ------------------------------------------
171 Then replace "SDLActivity" in AndroidManifest.xml with the name of your
172 class, .e.g. "MyGame"
174 ================================================================================
175 Customizing your application icon
176 ================================================================================
178 Conceptually changing your icon is just replacing the "ic_launcher.png" files in
179 the drawable directories under the res directory. There are four directories for
180 different screen sizes. These can be replaced with one dir called "drawable",
181 containing an icon file "ic_launcher.png" with dimensions 48x48 or 72x72.
183 You may need to change the name of your icon in AndroidManifest.xml to match
186 ================================================================================
188 ================================================================================
190 Any files you put in the "assets" directory of your android-project directory
191 will get bundled into the application package and you can load them using the
192 standard functions in SDL_rwops.h.
194 There are also a few Android specific functions that allow you to get other
195 useful paths for saving and loading data:
196 * SDL_AndroidGetInternalStoragePath()
197 * SDL_AndroidGetExternalStorageState()
198 * SDL_AndroidGetExternalStoragePath()
200 See SDL_system.h for more details on these functions.
202 The asset packaging system will, by default, compress certain file extensions.
203 SDL includes two asset file access mechanisms, the preferred one is the so
204 called "File Descriptor" method, which is faster and doesn'
t involve the Dalvik
205 GC, but given
this method does not work on compressed assets, there is also the
206 "Input Stream" method, which is automatically used as
a fall back
by SDL. You
207 may want to keep
this fact
in mind when building your APK, specially when large
209 For more information on which extensions
get compressed
by default and how to
210 disable
this behaviour, see
for example:
214 ================================================================================
215 Pause / Resume behaviour
216 ================================================================================
218 If SDL is compiled with SDL_ANDROID_BLOCK_ON_PAUSE defined (the
default),
219 the
event loop will block itself when the app is
paused (ie, when the user
220 returns to the
main Android dashboard). Blocking is better
in terms of battery
221 use, and it allows your app to spring back to life instantaneously after resume
222 (versus polling
for a resume
message).
224 Upon resume, SDL will attempt to restore the GL
context automatically.
225 In modern
devices (Android 3.0 and up)
this will most likely succeed and your
226 app can
continue to operate as it was.
228 However, there
's a chance (on older hardware, or on systems under heavy load),
229 where the GL context can not be restored. In that case you have to listen for
230 a specific message, (which is not yet implemented!) and restore your textures
231 manually or quit the app (which is actually the kind of behaviour you'll see
232 under iOS,
if the OS can not restore your GL
context it will just kill your app)
234 ================================================================================
235 Threads and the Java VM
236 ================================================================================
238 For
a quick tour on how Linux native
threads interoperate with the Java VM, take
241 If you want to use
threads in your SDL app, it
's strongly recommended that you
242 do so by creating them using SDL functions. This way, the required attach/detach
243 handling is managed by SDL automagically. If you have threads created by other
244 means and they make calls to SDL functions, make sure that you call
245 Android_JNI_SetupThread() before doing anything else otherwise SDL will attach
246 your thread automatically anyway (when you make an SDL call), but it'll never
249 ================================================================================
251 ================================================================================
253 You can use STL
in your project
by creating an Application.mk file
in the jni
254 folder and adding the following line:
256 APP_STL := stlport_static
258 For more information check out CPLUSPLUS-SUPPORT.html
in the NDK documentation.
260 ================================================================================
261 Additional documentation
262 ================================================================================
264 The documentation
in the NDK docs directory is very helpful
in understanding the
265 build process and how to work with native code on the Android platform.
267 The best place to
start is with docs/OVERVIEW.TXT
270 ================================================================================
272 ================================================================================
274 First make sure that you
've installed Eclipse and the Android extensions as described here:
275 https://developer.android.com/tools/sdk/eclipse-adt.html
277 Once you've copied the SDL android project and customized it, you can create an Eclipse project from it:
278 * File -> New -> Other
279 * Select the Android -> Android Project wizard and click Next
280 * Enter the name you
'd like your project to have
281 * Select "Create project from existing source" and browse for your project directory
282 * Make sure the Build Target is set to Android 3.1 (API 12)
286 ================================================================================
288 ================================================================================
290 There are some good tips and tricks for getting the most out of the
291 emulator here: https://developer.android.com/tools/devices/emulator.html
293 Especially useful is the info on setting up OpenGL ES 2.0 emulation.
295 Notice that this software emulator is incredibly slow and needs a lot of disk space.
296 Using a real device works better.
298 ================================================================================
300 ================================================================================
302 You can create and run an emulator from the Eclipse IDE:
303 * Window -> Android SDK and AVD Manager
305 You can see if adb can see any devices with the following command:
309 You can see the output of log messages on the default device with:
313 You can push files to the device with:
315 adb push local_file remote_path_and_file
317 You can push files to the SD Card at /sdcard, for example:
319 adb push moose.dat /sdcard/moose.dat
321 You can see the files on the SD card with a shell command:
323 adb shell ls /sdcard/
325 You can start a command shell on the default device with:
329 You can remove the library files of your project (and not the SDL lib files) with:
333 You can do a build with the following command:
337 You can see the complete command line that ndk-build is using by passing V=1 on the command line:
341 If your application crashes in native code, you can use addr2line to convert the
342 addresses in the stack trace to lines in your code.
344 For example, if your crash looks like this:
346 I/DEBUG ( 31): signal 11 (SIGSEGV), code 2 (SEGV_ACCERR), fault addr 400085d0
347 I/DEBUG ( 31): r0 00000000 r1 00001000 r2 00000003 r3 400085d4
348 I/DEBUG ( 31): r4 400085d0 r5 40008000 r6 afd41504 r7 436c6a7c
349 I/DEBUG ( 31): r8 436c6b30 r9 435c6fb0 10 435c6f9c fp 4168d82c
350 I/DEBUG ( 31): ip 8346aff0 sp 436c6a60 lr afd1c8ff pc afd1c902 cpsr 60000030
351 I/DEBUG ( 31): #00 pc 0001c902 /system/lib/libc.so
352 I/DEBUG ( 31): #01 pc 0001ccf6 /system/lib/libc.so
353 I/DEBUG ( 31): #02 pc 000014bc /data/data/org.libsdl.app/lib/libmain.so
354 I/DEBUG ( 31): #03 pc 00001506 /data/data/org.libsdl.app/lib/libmain.so
356 You can see that there's a crash
in the C library being called from the
main code.
357 I run addr2line with the debug version of my code:
359 arm-eabi-addr2line -C -
f -
e obj/local/armeabi/libmain.so
361 and then paste
in the number after
"pc" in the call stack, from the line that
I care about:
364 I get output from addr2line showing that it
's in the quit function, in testspriteminimal.c, on line 23.
366 You can add logging to your code to help show what's happening:
368 #include <android/log.h>
370 __android_log_print(ANDROID_LOG_INFO,
"foo",
"Something happened! x = %d",
x);
372 If you need to build without optimization turned on, you can create
a file called
373 "Application.mk" in the jni directory, with the following line
in it:
378 ================================================================================
380 ================================================================================
382 The best (and slowest) way to debug
memory issues on Android is valgrind.
383 Valgrind has support
for Android out of the
box, just grab code
using:
387 ... and follow the instructions
in the file README.android to build it.
389 One thing
I needed to
do on Mac OS X was change the
path to the toolchain,
390 and add ranlib to the environment variables:
391 export RANLIB=$NDKROOT/toolchains/arm-linux-androideabi-4.4.3/prebuilt/darwin-x86/bin/arm-linux-androideabi-ranlib
393 Once valgrind is built, you can create
a wrapper script to launch your
394 application with it, changing org.libsdl.app to your
package identifier:
396 --- start_valgrind_app -------------------
398 export TMPDIR=/data/data/org.libsdl.app
399 exec /data/local/Inst/bin/valgrind --log-file=/sdcard/valgrind.log --error-limit=no $*
400 ------------------------------------------
402 Then push it to the device:
404 adb push start_valgrind_app /data/local
406 and make it executable:
408 adb shell chmod 755 /data/local/start_valgrind_app
410 and tell Android to use the script to launch your application:
412 adb shell setprop wrap.org.libsdl.app "logwrapper /data/local/start_valgrind_app"
414 If the setprop command says "could not set property", it's likely that
415 your package name is too long and you should make it shorter by changing
416 AndroidManifest.xml and the path to your class file in android-project/src
418 You can then launch your application normally and waaaaaaaiiittt for it.
419 You can monitor the startup process with the logcat command above, and
420 when it's done (or even while it's running) you can grab the valgrind
423 adb pull /sdcard/valgrind.log
425 When you're done instrumenting with valgrind, you can disable the wrapper:
427 adb shell setprop wrap.org.libsdl.app ""
429 ================================================================================
431 ================================================================================
433 If you are developing on a compatible Tegra-based tablet, NVidia provides
434 Tegra Graphics Debugger at their website. Because SDL2 dynamically loads EGL
435 and GLES libraries, you must follow their instructions for installing the
436 interposer library on a rooted device. The non-rooted instructions are not
437 compatible with applications that use SDL2 for video.
439 The Tegra Graphics Debugger is available from NVidia here:
442 ================================================================================
443 Why is API level 10 the minimum required?
444 ================================================================================
446 API level 10 is the minimum required level at runtime (that is, on the device)
447 because SDL requires some functionality for running not
448 available on older devices. Since the incorporation of joystick support into SDL,
449 the minimum SDK required to *build* SDL is version 12. Devices running API levels
450 10-11 are still supported, only with the joystick functionality disabled.
452 Support for native OpenGL ES and ES2 applications was introduced in the NDK for
453 API level 4 and 8. EGL was made a stable API in the NDK for API level 9, which
454 has since then been obsoleted, with the recommendation to developers to bump the
455 required API level to 10.
456 As of this writing, according to https:
457 about 90% of the Android devices accessing Google Play support API level 10 or
460 ================================================================================
461 A note regarding the use of the "dirty rectangles" rendering technique
462 ================================================================================
464 If your app uses a variation of the "dirty rectangles" rendering technique,
465 where you only update a portion of the screen on each frame, you may notice a
466 variety of visual glitches on Android, that are not present on other platforms.
467 This is caused by SDL's use of EGL as the support system to handle OpenGL ES/ES2
468 contexts, in particular the use of the eglSwapBuffers function. As stated in the
469 documentation for the function "The contents of ancillary buffers are always
470 undefined after calling eglSwapBuffers".
471 Setting the EGL_SWAP_BEHAVIOR attribute of the surface to EGL_BUFFER_PRESERVED
472 is not possible for SDL as it requires EGL 1.4, available only on the API level
473 17+, so the only workaround available on this platform is to redraw the entire
478 ================================================================================
480 ================================================================================
482 - The number of buttons reported for each joystick is hardcoded to be 36, which
483 is the current maximum number of buttons Android can report.
SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char const char SDL_SCANF_FORMAT_STRING const char return SDL_ThreadFunction const char void return Uint32 return Uint32 SDL_AssertionHandler void SDL_SpinLock SDL_atomic_t int int return SDL_atomic_t return void void void return void return int return SDL_AudioSpec SDL_AudioSpec return int int return return int SDL_RWops int SDL_AudioSpec Uint8 Uint32 * e
GLint GLint GLint GLint GLint x
GLuint GLsizei const GLchar * message
static screen_context_t context
GLuint const GLchar * name
GLfixed GLfixed GLint GLint GLfixed points
static SDL_AudioDeviceID device
GLenum GLsizei GLsizei GLint * values
GLsizei const GLint * box
GLsizei GLsizei GLchar * source
GLsizei GLenum GLsizei GLsizei GLuint memory
static SDL_Thread * threads[6]
GLsizei const GLchar *const * path
GLboolean GLboolean GLboolean GLboolean a
GLsizei const GLchar *const * strings