Android: Add APK reading, closing app. Fix JNI env not attached to thread.

src/bundle.nim

@@ -97,5 +97,7 @@ when defined(android):
     export platform.myouAndroidGetJniEnv
     export platform.myouAndroidGetInternalDataPath
     export platform.myouAndroidGetExternalDataPath
+    export platform.myouAndroidAPKFilePointerLength
+    export platform.myouCloseMobileApp
 
 export platform.myouSetKeyboardVisible

src/platform/glfm_wrap.nim

@@ -324,8 +324,17 @@ proc myouAndroidGetJniEnv*(): pointer =
         # Ussing offsets from ANativeActivity
         let vm = cast[ptr ptr array[7, pointer]](activity[1])
         # Using offsets from jni.h
-        let GetEnv = cast[proc(vm: pointer, penv: var pointer, version: int32): int32 {.cdecl, gcsafe.}](vm[][6])
-        discard GetEnv(vm, result, 0x00010006'i32)
+        let getEnv = cast[proc(vm: pointer, penv: var pointer, version: int32): int32 {.cdecl, gcsafe.}](vm[][6])
+        let attachCurrentThread = cast[proc(vm: pointer, penv: ptr pointer, args: pointer): int32 {.cdecl, gcsafe.}](vm[][4])
+        let status = getEnv(vm, result, 0x00010006'i32)
+        if status == -2: # JNI_EDETACHED
+            # Attach thread to VM
+            if attachCurrentThread(vm, result.addr, nil) != 0:
+                echo "could not attach thread to VM"
+                result = nil
+        elif status != 0: # JNI_OK
+            result = nil
+        # TODO: do we ever need to detach a thread from the VM?
 
 proc myouAndroidGetInternalDataPath*(): string =
     when defined(android):
@@ -337,5 +346,39 @@ proc myouAndroidGetExternalDataPath*(): string =
         let activity = cast[ptr array[6, cstring]](window.glfmAndroidGetActivity())
         return $activity[5]
 
+when defined(android):
+    proc AAssetManager_open(asset_manager: pointer, filename: cstring, mode: int32): pointer {.importc,cdecl.}
+    proc AAsset_close(asset: pointer) {.importc,cdecl.}
+    proc AAsset_getBuffer(asset: pointer): pointer {.importc,cdecl.}
+    proc AAsset_getLength64(asset: pointer): int64 {.importc,cdecl.}
+    proc ANativeActivity_finish(activity: pointer) {.importc,cdecl.}
+
+type myouAAssetObj = object
+    asset: pointer
+    p*: pointer
+    len*: int
+
+type myouAAsset* = ref myouAAssetObj
+
+proc `=destroy`(x: var myouAAssetObj) =
+    if x.asset != nil:
+        AAsset_close(x.asset)
+        x.asset = nil
+
+proc myouAndroidAPKFilePointerLength*(path: string): myouAAsset =
+    let activity = cast[ptr array[9, pointer]](window.glfmAndroidGetActivity())
+    # Ussing offsets from ANativeActivity, assuming all pointers are aligned
+    let asset_manager = activity[8]
+    let asset = AAssetManager_open(asset_manager, path.cstring, 3) # 3 = buffer mode
+    if asset == nil:
+        echo "not found in APK: ", path
+        return myouAAsset()
+    let p = AAsset_getBuffer(asset)
+    let len = AAsset_getLength64(asset).int
+    myouAAsset(asset: asset, p: p, len: len)
+
 proc myouSetKeyboardVisible*(show: bool) =
     window.glfmSetKeyboardVisible(show)
+
+proc myouCloseMobileApp*() =
+    ANativeActivity_finish(window.glfmAndroidGetActivity())