Only use system gesture insets for exclusion rects with root ime view

- Instead of using the whole IME frame, we should only exclude the
  left and right regions for excluding the back gesture (the intention
  of the original change), otherwise the full IME frame will exclude
  the bottom gesture area which is respected by Launcher to prevent
  quickswitch.

Bug: 171501996
Test: Dump exclusion rects received by SysUI with normal IME (only edges)
      floating IME (no exclusion requested) and extract mode (only edges)


Change-Id: Id8e01d56190f8fafdc2da1cf95203e597acdb970
Merged-In: Id8e01d56190f8fafdc2da1cf95203e597acdb970
(cherry picked from commit 72e6319254769db69414f952c15dfaeeb14fc69a)
diff --git a/core/java/android/inputmethodservice/InputMethodService.java b/core/java/android/inputmethodservice/InputMethodService.java
index 4f0c84e..1e78153 100644
--- a/core/java/android/inputmethodservice/InputMethodService.java
+++ b/core/java/android/inputmethodservice/InputMethodService.java
@@ -71,6 +71,7 @@
 import android.view.Window;
 import android.view.WindowInsets;
 import android.view.WindowInsets.Side;
+import android.view.WindowInsets.Type;
 import android.view.WindowManager;
 import android.view.animation.AnimationUtils;
 import android.view.inputmethod.CompletionInfo;
@@ -104,7 +105,7 @@
 import java.io.PrintWriter;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
-import java.util.Collections;
+import java.util.ArrayList;
 
 /**
  * InputMethodService provides a standard implementation of an InputMethod,
@@ -850,10 +851,19 @@
 
     /** Set region of the keyboard to be avoided from back gesture */
     private void setImeExclusionRect(int visibleTopInsets) {
-        View inputFrameRootView = mInputFrame.getRootView();
-        Rect r = new Rect(0, visibleTopInsets, inputFrameRootView.getWidth(),
-                inputFrameRootView.getHeight());
-        inputFrameRootView.setSystemGestureExclusionRects(Collections.singletonList(r));
+        View rootView = mInputFrame.getRootView();
+        android.graphics.Insets systemGesture =
+                rootView.getRootWindowInsets().getInsetsIgnoringVisibility(Type.systemGestures());
+        ArrayList<Rect> exclusionRects = new ArrayList<>();
+        exclusionRects.add(new Rect(0,
+                visibleTopInsets,
+                systemGesture.left,
+                rootView.getHeight()));
+        exclusionRects.add(new Rect(rootView.getWidth() - systemGesture.right,
+                visibleTopInsets,
+                rootView.getWidth(),
+                rootView.getHeight()));
+        rootView.setSystemGestureExclusionRects(exclusionRects);
     }
 
     /**