Android: No longer require specification of NDK or Git paths in build.gradle.

Readme.md

@@ -55,21 +55,18 @@ the Android UI. Import the Gradle project located in `./Source/Android`, and the
 Gradle task `assembleDebug` to build, or `installDebug` to install the UI onto a connected device.
 
 In order to launch the app, you must build and include the native Dolphin libraries into the UI project.
-Building native code requires the [Android NDK](https://developer.android.com/tools/sdk/ndk/index.html).
+(Building native code requires the [Android NDK](https://developer.android.com/tools/sdk/ndk/index.html).)
 Android Studio will do this for you if you create `Source/Android/build.properties`, and place the
 following inside:
 
 ```
-gitPath=<git-path>
-ndkPath=<ndk-path>
 toolchain=<toolchain>
 abi=<abi>
 makeArgs=<make-args>
 ```
 
-Replace `<git-path>` with the absolute path to your machine's Git executable, `<ndk-path>` with the absolute
-path to where you installed your NDK, `<make-args>` with any arguments you want to pass to `make`, and the 
-rest depending on which platform the Android device you are targeting uses:
+Replace `<make-args>` with any arguments you want to pass to `make`, and the rest depending on which
+platform the Android device you are targeting uses:
 
 |Platform                 | `<abi>`     | `<toolchain>`             |
 |-------------------------|-------------|---------------------------|

Source/Android/app/build.gradle

@@ -82,8 +82,8 @@ task setupCMake(type: Exec) {
                 "-DANDROID_NATIVE_API_LEVEL=android-18",
                 "-DCMAKE_TOOLCHAIN_FILE=../../../android.toolchain.cmake",
                 "../../../../..",
-                "-DGIT_EXECUTABLE=" + buildProperties.gitPath,
-                "-DANDROID_NDK=" + buildProperties.ndkPath,
+                "-DGIT_EXECUTABLE=" + getGitPath(),
+                "-DANDROID_NDK=" + getNdkPath(),
                 "-DANDROID_TOOLCHAIN_NAME=" + buildProperties.toolchain,
                 "-DANDROID_ABI=" + buildProperties.abi
     } else {
@@ -111,4 +111,46 @@ task compileNative(type: Exec, dependsOn: 'setupCMake') {
         executable 'echo'
         args 'No build.properties found; skipping native build.'
     }
+}
+
+String getGitPath() {
+    try {
+        def stdout = new ByteArrayOutputStream()
+
+        exec {
+            commandLine 'which', 'git'
+            standardOutput = stdout
+        }
+
+        def gitPath = stdout.toString().trim()
+        project.logger.quiet("Gradle: Found git executuable:" + gitPath)
+
+        return gitPath
+    } catch (ignored) {
+        // Shouldn't happen. How did the user get this file without git?
+        project.logger.error("Gradle error: Couldn't find git executable.")
+        return null;
+    }
+}
+
+String getNdkPath() {
+    try {
+        def stdout = new ByteArrayOutputStream()
+
+        exec {
+            // ndk-build.cmd is a file unique to the root directory of android-ndk-r10d.
+            commandLine 'locate', 'ndk-build.cmd'
+            standardOutput = stdout
+        }
+
+        def ndkCmdPath = stdout.toString()
+        def ndkPath = ndkCmdPath.substring(0, ndkCmdPath.lastIndexOf('/'))
+
+        project.logger.quiet("Gradle: Found Android NDK:" + ndkPath)
+
+        return ndkPath
+    } catch (ignored) {
+        project.logger.error("Gradle error: Couldn't find NDK.")
+        return null;
+    }
 }