NdkBuildFlags

Added in 8.0.0

@Incubating
interface NdkBuildFlags

DSL object for per-variant ndk-build options, such as ndk-build arguments and compiler flags.

To learn more about the ndk-build toolchain, read the official NDK documentation about Building Your Project.

Summary

Public functions
Unit
abiFilters(vararg abiFilters: String)

Specifies the Application Binary Interfaces (ABI) that Gradle should build outputs for.
Unit
arguments(vararg arguments: String)

Specifies arguments for ndk-build.
Unit
cFlags(vararg cFlags: String)

Specifies flags for the C compiler.
Unit
cppFlags(vararg cppFlags: String)

Specifies flags for the C++ compiler.
Unit
targets(vararg targets: String)

Specifies the library and executable targets from your ndk-build project that Gradle should build.

Public properties
MutableSet<String>

Specifies the Application Binary Interfaces (ABI) that Gradle should build outputs for.
MutableList<String>

Specifies arguments for ndk-build.
MutableList<String>

Specifies flags for the C compiler.
MutableList<String>

Specifies flags for the C++ compiler.
MutableSet<String>

Specifies the library and executable targets from your ndk-build project that Gradle should build.

Public functions

abiFilters

Added in 8.0.0
fun abiFilters(vararg abiFilters: String): Unit

Specifies the Application Binary Interfaces (ABI) that Gradle should build outputs for. The ABIs that Gradle packages into your APK are determined by android.defaultConfig.ndk.abiFilter

In most cases, you need to specify ABIs using only android.defaultConfig.ndk.abiFilter, because it tells Gradle which ABIs to both build and package into your APK. However, if you want to control what Gradle should build, independently of what you want it to package into your APK, configure this property with the ABIs you want Gradle to build.

To further reduce the size of your APK, consider configuring multiple APKs based on ABI—instead of creating one large APK with all versions of your native libraries, Gradle creates a separate APK for each ABI you want to support and only packages the files each ABI needs.

By default, this property is null.

since 2.2.0

arguments

Added in 8.0.0
fun arguments(vararg arguments: String): Unit

Specifies arguments for ndk-build.

The properties you can configure are the same as those available in your Android.mk and Application.mk scripts.

See the ndk-build script.

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor you configure.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Set number of jobs used for each ndk-build invocation.
                arguments += "-j16"
            }
        }
    }
}

By default, this property is null.

since 2.2.0

cFlags

Added in 8.0.0
fun cFlags(vararg cFlags: String): Unit

Specifies flags for the C compiler.

The following sample enables format macro constants:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Sets an optional flag for the C compiler.
                cFlags "-D__STDC_FORMAT_MACROS"
            }
        }
    }
}

By default, this property is null.

since 2.2.0

cppFlags

Added in 8.0.0
fun cppFlags(vararg cppFlags: String): Unit

Specifies flags for the C++ compiler.

The following sample enables RTTI (RunTime Type Information) support and C++ exceptions:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Sets optional flags for the C++ compiler.
                cppFlags "-fexceptions", "-frtti"
            }
        }
    }
}

By default, this property is null.

since 2.2.0

targets

Added in 8.0.0
fun targets(vararg targets: String): Unit

Specifies the library and executable targets from your ndk-build project that Gradle should build.

For example, if your ndk-build project defines multiple libraries and executables, you can tell Gradle to build only a subset of those outputs as follows:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // The following tells Gradle to build only the "libexample-one.so" and
                // "my-executible-two" targets from the linked ndk-build project. If you don't
                // configure this property, Gradle builds all executables and shared object
                // libraries that you define in your ndk-build project. However, by default,
                // Gradle packages only the shared libraries in your APK.
                targets "libexample-one.so",
                        // You need to configure this executable and its sources in your
                        // Android.mk file like you would any other library, except you must
                        // specify "include $(BUILD_EXECUTABLE)". Building executables from
                        // your native sources is optional, and building native libraries to
                        // package into your APK satisfies most project requirements.
                        "my-executible-demo"
            }
        }
    }
}

If you don't configure this property, Gradle builds all executables and shared object libraries that you define in your ndk-build project. However, by default, Gradle packages only the shared libraries in your APK.

since 2.2.0

Public properties

abiFilters

Added in 8.0.0
val abiFilters: MutableSet<String>

Specifies the Application Binary Interfaces (ABI) that Gradle should build outputs for. The ABIs that Gradle packages into your APK are determined by android.defaultConfig.ndk.abiFilter

In most cases, you need to specify ABIs using only android.defaultConfig.ndk.abiFilter, because it tells Gradle which ABIs to both build and package into your APK. However, if you want to control what Gradle should build, independently of what you want it to package into your APK, configure this property with the ABIs you want Gradle to build.

To further reduce the size of your APK, consider configuring multiple APKs based on ABI—instead of creating one large APK with all versions of your native libraries, Gradle creates a separate APK for each ABI you want to support and only packages the files each ABI needs.

By default, this property is null.

since 2.2.0

arguments

Added in 8.0.0
val arguments: MutableList<String>

Specifies arguments for ndk-build.

The properties you can configure are the same as those available in your Android.mk and Application.mk scripts. The following sample specifies the Application.mk for the ndk-build project:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor you configure.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Passes an optional argument to ndk-build.
                arguments "NDK_MODULE_PATH+=../../third_party/modules"
            }
        }
    }
}

By default, this property is null.

since 2.2.0

cFlags

Added in 8.0.0
val cFlags: MutableList<String>

Specifies flags for the C compiler.

The following sample enables format macro constants:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Sets an optional flag for the C compiler.
                cFlags "-D__STDC_FORMAT_MACROS"
            }
        }
    }
}

By default, this property is null.

since 2.2.0

cppFlags

Added in 8.0.0
val cppFlags: MutableList<String>

Specifies flags for the C++ compiler.

The following sample enables RTTI (RunTime Type Information) support and C++ exceptions:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Sets optional flags for the C++ compiler.
                cppFlags "-fexceptions", "-frtti"
            }
        }
    }
}

By default, this property is null.

since 2.2.0

targets

Added in 8.0.0
val targets: MutableSet<String>

Specifies the library and executable targets from your ndk-build project that Gradle should build.

For example, if your ndk-build project defines multiple libraries and executables, you can tell Gradle to build only a subset of those outputs as follows:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // The following tells Gradle to build only the "libexample-one.so" and
                // "my-executible-two" targets from the linked ndk-build project. If you don't
                // configure this property, Gradle builds all executables and shared object
                // libraries that you define in your ndk-build project. However, by default,
                // Gradle packages only the shared libraries in your APK.
                targets "libexample-one.so",
                        // You need to configure this executable and its sources in your
                        // Android.mk file like you would any other library, except you must
                        // specify "include $(BUILD_EXECUTABLE)". Building executables from
                        // your native sources is optional, and building native libraries to
                        // package into your APK satisfies most project requirements.
                        "my-executible-demo"
            }
        }
    }
}

If you don't configure this property, Gradle builds all executables and shared object libraries that you define in your ndk-build project. However, by default, Gradle packages only the shared libraries in your APK.

since 2.2.0