android: Use ndk-context instead of ndk-glue to access JVM

This makes webbrowser-rs more compatible with different Android
application frameworks by not imposing that applications must use
ndk-glue.

Fixes: amodm#51

Cargo.toml

@@ -28,8 +28,8 @@ winapi = { version = "0.3", features = ["combaseapi", "objbase", "shellapi", "wi
 widestring = { version = ">= 0.5, <=1.0" }
 
 [target.'cfg(target_os = "android")'.dependencies]
-jni = "0.19"
-ndk-glue = { version = ">= 0.3, <= 0.7" }
+jni = "0.20"
+ndk-context = "0.1"
 
 [target.'cfg(target_os = "ios")'.dependencies]
 raw-window-handle = "0.5.0"
@@ -41,3 +41,6 @@ actix-files = "0.6"
 crossbeam-channel = "0.5"
 tokio = { version = "1", features = ["full"] }
 urlencoding = "2.1"
+
+[target.'cfg(target_os = "android")'.dev-dependencies]
+ndk-glue = { version = ">= 0.3, <= 0.7" }

src/android.rs

@@ -24,9 +24,9 @@ pub fn open_browser_default(url: &str, options: &BrowserOptions) -> Result<()> {
     }
 
     // Create a VM for executing Java calls
-    let native_activity = ndk_glue::native_activity();
-    let vm_ptr = native_activity.vm();
-    let vm = unsafe { jni::JavaVM::from_raw(vm_ptr) }.unwrap();
+    let ctx = ndk_context::android_context();
+    let vm = unsafe { jni::JavaVM::from_raw(ctx.vm() as _).expect("Expected to find JVM via ndk_context crate") };
+    let activity = unsafe { jni::objects::JObject::from_raw(ctx.context() as _) };
     let env = vm.attach_current_thread().map_err(|_| -> Error {
         Error::new(ErrorKind::Other, "Failed to attach current thread")
     })?;
@@ -71,7 +71,7 @@ pub fn open_browser_default(url: &str, options: &BrowserOptions) -> Result<()> {
 
     // Start the intent activity.
     env.call_method(
-        native_activity.activity(),
+        activity,
         "startActivity",
         "(Landroid/content/Intent;)V",
         &[JValue::Object(intent)],