Android: hook into pre draw and attach listener to deliver safe area

Instead of relying only on setOnApplyWindowInsetsListener() and
trying to guess when to try and deliver root decor insets in case
the setOnApplyWindowInsetsListener() doesn't deliver the view's
insets early on, a cleaner way is to hook into
addOnAttachStateChangeListener() and OnPreDrawListener() listeners.
With this approach we guarantee that at least in one of those
cases, especially OnPreDrawListener(), we would be guaranteed
to get the insets when the view is attached. With this approach
we only need to get once such event and from there forward
we rely still on setOnApplyWindowInsetsListener().

Fixes: QTBUG-135808
Pick-to: 6.9 6.10
Change-Id: I05bf3009eb9a33f104d01d29e7f02d780900fc66
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/android/jar/src/org/qtproject/qt/android/QtWindow.java

@@ -15,8 +15,8 @@ import android.view.MotionEvent;
 import android.view.Surface;
 import android.view.View;
 import android.view.ViewGroup;
+import android.view.ViewTreeObserver;
 import android.view.WindowInsets;
-
 import android.os.Build;
 
 import java.util.HashMap;
@@ -30,6 +30,7 @@ class QtWindow extends QtLayout implements QtSurfaceInterface {
     private GestureDetector m_gestureDetector;
     private final QtEditText m_editText;
     private final QtInputConnection.QtInputConnectionListener m_inputConnectionListener;
+    private boolean m_firstSafeMarginsDelivered = false;
 
     private static native void setSurface(int windowId, Surface surface);
     private static native void safeAreaMarginsChanged(Insets insets, int id);
@@ -75,46 +76,71 @@ class QtWindow extends QtLayout implements QtSurfaceInterface {
                 });
             m_gestureDetector.setIsLongpressEnabled(true);
         });
+
+        registerSafeAreaMarginsListener();
     }
 
-    @UsedFromNativeCode
-    void registerSafeAreaMarginsListner(boolean isTopLevel, boolean isSameWindowAndScreenSize)
+    void registerSafeAreaMarginsListener()
     {
         if (!(getContext() instanceof QtActivityBase))
             return;
 
         setOnApplyWindowInsetsListener((view, insets) -> {
-            Insets safeInsets = getSafeInsets(view, insets);
+            WindowInsets windowInsets = view.onApplyWindowInsets(insets);
+            Insets safeInsets = getSafeInsets(this, windowInsets);
             safeAreaMarginsChanged(safeInsets, getId());
-            return getConsumedInsets(insets);
+            m_firstSafeMarginsDelivered = true;
+
+            return windowInsets;
         });
 
-        // NOTE: if the window size fits the screen geometry (i.e. edge-to-edge case),
-        // assume this window is the main window and initialize its safe margins with
-        // the insets of the decor view.
-        if (isTopLevel && isSameWindowAndScreenSize) {
-            QtNative.runAction(() -> {
-                // NOTE: The callback onApplyWindowInsetsListener() is not being triggered during
-                // startup, so this is a Workaround to get the safe area margins at startup.
-                // Initially, set the root view insets to the current window, then if the insets
-                // change later, we can rely on setOnApplyWindowInsetsListener() being called.
-                View decorView = ((Activity) getContext()).getWindow().getDecorView();
-                WindowInsets rootInsets = decorView.getRootWindowInsets();
-                Insets rootSafeInsets = getSafeInsets(decorView, rootInsets);
-                safeAreaMarginsChanged(rootSafeInsets, getId());
+        // If the window is attached, try to directly deliver root insets
+        if (isAttachedToWindow()) {
+            WindowInsets insets = getRootWindowInsets();
+            if (insets != null) {
+                safeAreaMarginsChanged(getSafeInsets(this, insets), getId());
+                m_firstSafeMarginsDelivered = true;
+            }
+        } else { // Otherwise request it upon attachement
+            addOnAttachStateChangeListener(new View.OnAttachStateChangeListener() {
+                @Override
+                public void onViewAttachedToWindow(View view) {
+                    view.removeOnAttachStateChangeListener(this);
+                    view.requestApplyInsets();
+                }
+
+                @Override
+                public void onViewDetachedFromWindow(View view) {}
             });
         }
 
-        QtNative.runAction(() -> requestApplyInsets());
-    }
+        // Further, tag into pre draw to deliver safe area margins early on
+        if (!m_firstSafeMarginsDelivered) {
+            ViewTreeObserver.OnPreDrawListener listener = new ViewTreeObserver.OnPreDrawListener() {
+                @Override
+                public boolean onPreDraw() {
+                    if (m_firstSafeMarginsDelivered) {
+                        getViewTreeObserver().removeOnPreDrawListener(this);
+                        return true;
+                    }
 
-    @SuppressWarnings("deprecation")
-    WindowInsets getConsumedInsets(WindowInsets insets)
-    {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R)
-            return WindowInsets.CONSUMED;
-        else
-            return insets.consumeSystemWindowInsets();
+                    if (isAttachedToWindow()) {
+                        WindowInsets insets = getRootWindowInsets();
+                        if (insets != null) {
+                            getViewTreeObserver().removeOnPreDrawListener(this);
+                            safeAreaMarginsChanged(getSafeInsets(QtWindow.this, insets), getId());
+                            m_firstSafeMarginsDelivered = true;
+                            return true;
+                        }
+                    }
+
+                    requestApplyInsets();
+
+                    return true;
+                }
+            };
+            getViewTreeObserver().addOnPreDrawListener(listener);
+        }
     }
 
     @SuppressWarnings("deprecation")

src/plugins/platforms/android/qandroidplatformwindow.cpp

@@ -97,11 +97,6 @@ void QAndroidPlatformWindow::initialize()
     }
     qCDebug(lcQpaWindow) << "Window" << m_nativeViewId << "using surface container type"
                          << static_cast<int>(m_surfaceContainerType);
-
-    const bool isSameWindowAndScreenSize = geometry().size() == screen()->geometry().size();
-    m_nativeQtWindow.callMethod("registerSafeAreaMarginsListner",
-                                window->isTopLevel(), isSameWindowAndScreenSize);
-
 }
 
 QAndroidPlatformWindow::~QAndroidPlatformWindow()