From 4a2a45dde3659418be419ee5773ec8ac7f6b08b1 Mon Sep 17 00:00:00 2001
From: assiduous <assiduous@diligentgraphics.com>
Date: Mon, 27 Apr 2020 16:03:37 -0700
Subject: Updated Android native app to better handle orientation changes

---
 NativeApp/include/Android/AndroidAppBase.hpp | 23 +++---------------
 NativeApp/src/Android/AndroidAppBase.cpp     | 35 +++++++++++++++++++++-------
 2 files changed, 29 insertions(+), 29 deletions(-)

(limited to 'NativeApp')

diff --git a/NativeApp/include/Android/AndroidAppBase.hpp b/NativeApp/include/Android/AndroidAppBase.hpp
index 21cd937..403c62d 100644
--- a/NativeApp/include/Android/AndroidAppBase.hpp
+++ b/NativeApp/include/Android/AndroidAppBase.hpp
@@ -42,31 +42,16 @@ public:
     void           SetState(android_app* state, const char* native_activity_class_name);
     void           InitSensors();
     void           ProcessSensors(int32_t id);
-    void           DrawFrame();
+    virtual void   DrawFrame();
     bool           IsReady();
     virtual void   TrimMemory()  = 0;
     virtual void   TermDisplay() = 0;
     static int32_t HandleInput(android_app* app, AInputEvent* event);
     static void    HandleCmd(android_app* app, int32_t cmd);
 
-    bool CheckWindowSizeChanged()
-    {
-        auto new_window_width  = ANativeWindow_getWidth(app_->window);
-        auto new_window_height = ANativeWindow_getHeight(app_->window);
-        if (new_window_width != window_width_ || new_window_height != window_height_)
-        {
-            window_width_  = new_window_width;
-            window_height_ = new_window_height;
-            return true;
-        }
-        else
-            return false;
-    }
-
 protected:
     virtual void Initialize()
     {
-        CheckWindowSizeChanged();
     }
 
     virtual int Resume(ANativeWindow* window) = 0;
@@ -100,10 +85,8 @@ private:
     void ShowUI();
     void UpdateFPS(float fFPS);
 
-    bool    initialized_resources_ = false;
-    bool    has_focus_             = false;
-    int32_t window_width_          = 0;
-    int32_t window_height_         = 0;
+    bool initialized_resources_ = false;
+    bool has_focus_             = false;
 
     ASensorManager*    sensor_manager_       = nullptr;
     const ASensor*     accelerometer_sensor_ = nullptr;
diff --git a/NativeApp/src/Android/AndroidAppBase.cpp b/NativeApp/src/Android/AndroidAppBase.cpp
index bc79470..3af8116 100644
--- a/NativeApp/src/Android/AndroidAppBase.cpp
+++ b/NativeApp/src/Android/AndroidAppBase.cpp
@@ -72,12 +72,6 @@ void AndroidAppBase::InitSensors()
 //
 void AndroidAppBase::DrawFrame()
 {
-    // APP_CMD_CONFIG_CHANGED event is generated seveal frames
-    // before the screen is actually resized. The only robust way
-    // to detect window resize is to check it very frame
-    if (CheckWindowSizeChanged())
-        WindowResize(window_width_, window_height_);
-
     float fFPS;
     if (monitor_.Update(fFPS))
     {
@@ -135,11 +129,34 @@ void AndroidAppBase::HandleCmd(struct android_app* app, int32_t cmd)
             break;
 
         case APP_CMD_CONFIG_CHANGED:
+        {
+            // This callback is not reliable for handling orientation changes. Depending on the
+            // device, it may be called before or after the surface has been actually resized.
+            break;
+        }
+
+        // Note that as of NDK r21b (21.1.6352462), APP_CMD_WINDOW_RESIZED event is never generated
+        // by android_native_app_glue.
+        // Also note that modifying android_native_app_glue to handle onNativeWindowResized
+        // callback (as suggested in https://android-developers.googleblog.com/2020/02/handling-device-orientation-efficiently.html)
+        // does not work either - the callback is only called once after the window has been created.
         case APP_CMD_WINDOW_RESIZED:
-            // This does not work as the screen resizes few frames
-            // after the event has been received
-            // eng->WindowResize(0,0);
+        {
+            auto new_window_width  = ANativeWindow_getWidth(app->window);
+            auto new_window_height = ANativeWindow_getHeight(app->window);
+            eng->WindowResize(new_window_width, new_window_height);
             break;
+        }
+
+        // Note that as of NDK r21b (21.1.6352462), APP_CMD_CONTENT_RECT_CHANGED event is never
+        // generated by android_native_app_glue
+        case APP_CMD_CONTENT_RECT_CHANGED:
+        {
+            auto new_window_width  = app->contentRect.right - app->contentRect.left;
+            auto new_window_height = app->contentRect.bottom - app->contentRect.top;
+            eng->WindowResize(new_window_width, new_window_height);
+            break;
+        }
 
         case APP_CMD_TERM_WINDOW:
             // The window is being hidden or closed, clean it up.
-- 
cgit v1.2.3