|
1 | | -# Android |
| 1 | +# Android Demo App |
2 | 2 |
|
3 | | -## Demo applications and tutorials |
| 3 | +Please refer to [pytorch-labs/executorch-examples](https://github.com/pytorch-labs/executorch-examples/tree/main/dl3/android/DeepLabV3Demo) for the Android demo app based on [ExecuTorch](https://github.com/pytorch/executorch). |
4 | 4 |
|
5 | | -Demo applications with code walk-through can be find in [this github repo](https://github.com/pytorch/android-demo-app). |
6 | | - |
7 | | -## Publishing |
8 | | - |
9 | | -##### Release |
10 | | -Release artifacts are published to jcenter: |
11 | | - |
12 | | -```groovy |
13 | | -repositories { |
14 | | - jcenter() |
15 | | -} |
16 | | -
|
17 | | -# lite interpreter build |
18 | | -dependencies { |
19 | | - implementation 'org.pytorch:pytorch_android_lite:1.10.0' |
20 | | - implementation 'org.pytorch:pytorch_android_torchvision_lite:1.10.0' |
21 | | -} |
22 | | -
|
23 | | -# full jit build |
24 | | -dependencies { |
25 | | - implementation 'org.pytorch:pytorch_android:1.10.0' |
26 | | - implementation 'org.pytorch:pytorch_android_torchvision:1.10.0' |
27 | | -} |
28 | | -``` |
29 | | - |
30 | | -##### Nightly |
31 | | - |
32 | | -Nightly(snapshots) builds are published every night from `master` branch to [nexus sonatype snapshots repository](https://oss.sonatype.org/#nexus-search;quick~pytorch_android) |
33 | | - |
34 | | -To use them repository must be specified explicitly: |
35 | | -```groovy |
36 | | -repositories { |
37 | | - maven { |
38 | | - url "https://oss.sonatype.org/content/repositories/snapshots" |
39 | | - } |
40 | | -} |
41 | | -
|
42 | | -# lite interpreter build |
43 | | -dependencies { |
44 | | - ... |
45 | | - implementation 'org.pytorch:pytorch_android_lite:1.12.0-SNAPSHOT' |
46 | | - implementation 'org.pytorch:pytorch_android_torchvision_lite:1.12.0-SNAPSHOT' |
47 | | - ... |
48 | | -} |
49 | | -
|
50 | | -# full jit build |
51 | | -dependencies { |
52 | | - ... |
53 | | - implementation 'org.pytorch:pytorch_android:1.12.0-SNAPSHOT' |
54 | | - implementation 'org.pytorch:pytorch_android_torchvision:1.12.0-SNAPSHOT' |
55 | | - ... |
56 | | -} |
57 | | -``` |
58 | | -The current nightly(snapshots) version is the value of `VERSION_NAME` in `gradle.properties` in current folder, at this moment it is `1.8.0-SNAPSHOT`. |
59 | | - |
60 | | -## Building PyTorch Android from Source |
61 | | - |
62 | | -In some cases you might want to use a local build of pytorch android, for example you may build custom libtorch binary with another set of operators or to make local changes. |
63 | | - |
64 | | -For this you can use `./scripts/build_pytorch_android.sh` script. |
65 | | -```bash |
66 | | -git clone https://github.com/pytorch/pytorch.git |
67 | | -cd pytorch |
68 | | -git submodule update --init --recursive |
69 | | -bash ./scripts/build_pytorch_android.sh |
70 | | -``` |
71 | | - |
72 | | -The workflow contains several steps: |
73 | | - |
74 | | -1\. Build libtorch for android for all 4 android abis (armeabi-v7a, arm64-v8a, x86, x86_64) |
75 | | - |
76 | | -2\. Create symbolic links to the results of those builds: |
77 | | -`android/pytorch_android/src/main/jniLibs/${abi}` to the directory with output libraries |
78 | | -`android/pytorch_android/src/main/cpp/libtorch_include/${abi}` to the directory with headers. These directories are used to build `libpytorch.so` library that will be loaded on android device. |
79 | | - |
80 | | -3\. And finally run `gradle` in `android/pytorch_android` directory with task `assembleRelease` |
81 | | - |
82 | | -Script requires that Android SDK, Android NDK and gradle are installed. |
83 | | -They are specified as environment variables: |
84 | | - |
85 | | -`ANDROID_HOME` - path to [Android SDK](https://developer.android.com/studio/command-line/sdkmanager.html) |
86 | | - |
87 | | -`ANDROID_NDK` - path to [Android NDK](https://developer.android.com/studio/projects/install-ndk). It's recommended to use NDK 21.x. |
88 | | - |
89 | | -`GRADLE_HOME` - path to [gradle](https://gradle.org/releases/) |
90 | | - |
91 | | - |
92 | | -After successful build you should see the result as aar file: |
93 | | - |
94 | | -```bash |
95 | | -$ find pytorch_android/build/ -type f -name *aar |
96 | | -pytorch_android/build/outputs/aar/pytorch_android.aar |
97 | | -pytorch_android_torchvision/build/outputs/aar/pytorch_android.aar |
98 | | -``` |
99 | | - |
100 | | -It can be used directly in android projects, as a gradle dependency: |
101 | | -```groovy |
102 | | -allprojects { |
103 | | - repositories { |
104 | | - flatDir { |
105 | | - dirs 'libs' |
106 | | - } |
107 | | - } |
108 | | -} |
109 | | -
|
110 | | -dependencies { |
111 | | - implementation(name:'pytorch_android', ext:'aar') |
112 | | - implementation(name:'pytorch_android_torchvision', ext:'aar') |
113 | | - ... |
114 | | - implementation 'com.facebook.soloader:nativeloader:0.10.5' |
115 | | - implementation 'com.facebook.fbjni:fbjni-java-only:0.2.2' |
116 | | -} |
117 | | -``` |
118 | | -We also have to add all transitive dependencies of our aars. |
119 | | -As `pytorch_android` [depends](https://github.com/pytorch/pytorch/blob/master/android/pytorch_android/build.gradle#L76-L77) on `'com.facebook.soloader:nativeloader:0.10.5'` and `'com.facebook.fbjni:fbjni-java-only:0.2.2'`, we need to add them. |
120 | | -(In case of using maven dependencies they are added automatically from `pom.xml`). |
121 | | - |
122 | | -You can check out [test app example](https://github.com/pytorch/pytorch/blob/master/android/test_app/app/build.gradle) that uses aars directly. |
123 | | - |
124 | | -## Linking to prebuilt libtorch library from gradle dependency |
125 | | - |
126 | | -In some cases, you may want to use libtorch from your android native build. |
127 | | -You can do it without building libtorch android, using native libraries from PyTorch android gradle dependency. |
128 | | -For that, you will need to add the next lines to your gradle build. |
129 | | -```groovy |
130 | | -android { |
131 | | -... |
132 | | - configurations { |
133 | | - extractForNativeBuild |
134 | | - } |
135 | | -... |
136 | | - compileOptions { |
137 | | - externalNativeBuild { |
138 | | - cmake { |
139 | | - arguments "-DANDROID_STL=c++_shared" |
140 | | - } |
141 | | - } |
142 | | - } |
143 | | -... |
144 | | - externalNativeBuild { |
145 | | - cmake { |
146 | | - path "CMakeLists.txt" |
147 | | - } |
148 | | - } |
149 | | -} |
150 | | -
|
151 | | -dependencies { |
152 | | - extractForNativeBuild('org.pytorch:pytorch_android:1.10.0') |
153 | | -} |
154 | | -
|
155 | | -task extractAARForNativeBuild { |
156 | | - doLast { |
157 | | - configurations.extractForNativeBuild.files.each { |
158 | | - def file = it.absoluteFile |
159 | | - copy { |
160 | | - from zipTree(file) |
161 | | - into "$buildDir/$file.name" |
162 | | - include "headers/**" |
163 | | - include "jni/**" |
164 | | - } |
165 | | - } |
166 | | - } |
167 | | -} |
168 | | -
|
169 | | -tasks.whenTaskAdded { task -> |
170 | | - if (task.name.contains('externalNativeBuild')) { |
171 | | - task.dependsOn(extractAARForNativeBuild) |
172 | | - } |
173 | | -} |
174 | | -``` |
175 | | - |
176 | | -pytorch_android aar contains headers to link in `headers` folder and native libraries in `jni/$ANDROID_ABI/`. |
177 | | -As PyTorch native libraries use `ANDROID_STL` - we should use `ANDROID_STL=c++_shared` to have only one loaded binary of STL. |
178 | | - |
179 | | -The added task will unpack them to gradle build directory. |
180 | | - |
181 | | -In your native build you can link to them adding these lines to your CMakeLists.txt: |
182 | | - |
183 | | - |
184 | | -```cmake |
185 | | -# Relative path of gradle build directory to CMakeLists.txt |
186 | | -set(build_DIR ${CMAKE_SOURCE_DIR}/build) |
187 | | -
|
188 | | -file(GLOB PYTORCH_INCLUDE_DIRS "${build_DIR}/pytorch_android*.aar/headers") |
189 | | -file(GLOB PYTORCH_LINK_DIRS "${build_DIR}/pytorch_android*.aar/jni/${ANDROID_ABI}") |
190 | | -
|
191 | | -set(BUILD_SUBDIR ${ANDROID_ABI}) |
192 | | -target_include_directories(${PROJECT_NAME} PRIVATE |
193 | | - ${PYTORCH_INCLUDE_DIRS} |
194 | | -) |
195 | | -
|
196 | | -find_library(PYTORCH_LIBRARY pytorch_jni |
197 | | - PATHS ${PYTORCH_LINK_DIRS} |
198 | | - NO_CMAKE_FIND_ROOT_PATH) |
199 | | -
|
200 | | -find_library(FBJNI_LIBRARY fbjni |
201 | | - PATHS ${PYTORCH_LINK_DIRS} |
202 | | - NO_CMAKE_FIND_ROOT_PATH) |
203 | | -
|
204 | | -target_link_libraries(${PROJECT_NAME} |
205 | | - ${PYTORCH_LIBRARY}) |
206 | | - ${FBJNI_LIBRARY}) |
207 | | -
|
208 | | -``` |
209 | | -If your CMakeLists.txt file is located in the same directory as your build.gradle, `set(build_DIR ${CMAKE_SOURCE_DIR}/build)` should work for you. But if you have another location of it, you may need to change it. |
210 | | - |
211 | | -After that, you can use libtorch C++ API from your native code. |
212 | | -```cpp |
213 | | -#include <string> |
214 | | -#include <ATen/NativeFunctions.h> |
215 | | -#include <torch/script.h> |
216 | | -namespace pytorch_testapp_jni { |
217 | | -namespace { |
218 | | - struct JITCallGuard { |
219 | | - c10::InferenceMode guard; |
220 | | - torch::jit::GraphOptimizerEnabledGuard no_optimizer_guard{false}; |
221 | | - }; |
222 | | -} |
223 | | - |
224 | | -void loadAndForwardModel(const std::string& modelPath) { |
225 | | - JITCallGuard guard; |
226 | | - torch::jit::Module module = torch::jit::load(modelPath); |
227 | | - module.eval(); |
228 | | - torch::Tensor t = torch::randn({1, 3, 224, 224}); |
229 | | - c10::IValue t_out = module.forward({t}); |
230 | | -} |
231 | | -} |
232 | | -``` |
233 | | -
|
234 | | -To load torchscript model for mobile we need some special setup which is placed in `struct JITCallGuard` in this example. It may change in future, you can track the latest changes keeping an eye in our [pytorch android jni code]([https://github.com/pytorch/pytorch/blob/master/android/pytorch_android/src/main/cpp/pytorch_jni_jit.cpp#L28) |
235 | | -
|
236 | | -[Example of linking to libtorch from aar](https://github.com/pytorch/pytorch/tree/master/android/test_app) |
237 | | -
|
238 | | -## PyTorch Android API Javadoc |
239 | | -
|
240 | | -You can find more details about the PyTorch Android API in the [Javadoc](https://pytorch.org/javadoc/). |
| 5 | +Please join our [Discord](https://discord.com/channels/1334270993966825602/1349854760299270284) for any questions. |
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