Android: Probe for virtual keyboard height

Knowing the real virtual keyboard height will be easier for us to
decide if we pan or resize the current view.
The virtual keyboard is re-shown if current virtual keyboard height
is different from previous one.

Task-number: QTBUG-43739
Change-Id: I1bb41a70cced4c1d0e5f05a6c554831459b7a917
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

src/android/jar/src/org/qtproject/qt5/android/QtActivityDelegate.java

@@ -42,6 +42,7 @@ import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.res.Configuration;
 import android.graphics.drawable.ColorDrawable;
+import android.graphics.Rect;
 import android.net.LocalServerSocket;
 import android.net.LocalSocket;
 import android.os.Build;
@@ -67,7 +68,6 @@ import android.view.ViewGroup;
 import android.view.WindowManager;
 import android.view.inputmethod.InputMethodManager;
 import android.view.ViewTreeObserver;
-import android.graphics.Rect;
 
 import java.io.BufferedReader;
 import java.io.DataOutputStream;
@@ -125,6 +125,9 @@ public class QtActivityDelegate
     private boolean m_keyboardIsVisible = false;
     public boolean m_backKeyPressedSent = false;
     private long m_showHideTimeStamp = System.nanoTime();
+    private int m_portraitKeyboardHeight = 0;
+    private int m_landscapeKeyboardHeight = 0;
+    private int m_probeKeyboardHeightDelay = 50; // ms
 
     public void setFullScreen(boolean enterFullScreen)
     {
@@ -247,19 +250,26 @@ public class QtActivityDelegate
         }, 5);
     }
 
-    public void showSoftwareKeyboard(int x, int y, int width, int height, int inputHints, int enterKeyType)
+    public void showSoftwareKeyboard(final int x, final int y, final int width, final int height, final int inputHints, final int enterKeyType)
     {
         if (m_imm == null)
             return;
 
+        DisplayMetrics metrics = new DisplayMetrics();
+        m_activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
+
+        // If the screen is in portrait mode than we estimate that keyboard height will not be higher than 2/5 of the screen.
+        // else than we estimate that keyboard height will not be higher than 2/3 of the screen
+        final int visibleHeight;
+        if (metrics.widthPixels < metrics.heightPixels)
+            visibleHeight = m_portraitKeyboardHeight != 0 ? m_portraitKeyboardHeight : metrics.heightPixels * 3 / 5;
+        else
+            visibleHeight = m_landscapeKeyboardHeight != 0 ? m_landscapeKeyboardHeight : metrics.heightPixels / 3;
+
         if (m_softInputMode != 0) {
             m_activity.getWindow().setSoftInputMode(m_softInputMode);
-            // softInputIsHidden is true if SOFT_INPUT_STATE_HIDDEN or SOFT_INPUT_STATE_ALWAYS_HIDDEN is set.
-            final boolean softInputIsHidden = (m_softInputMode & WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN) != 0;
-            if (softInputIsHidden)
-               return;
         } else {
-            if (height > m_layout.getHeight() * 2 / 3)
+            if (height > visibleHeight)
                 m_activity.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_UNCHANGED | WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
             else
                 m_activity.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_UNCHANGED | WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);
@@ -366,6 +376,38 @@ public class QtActivityDelegate
                                 //FALLTHROUGH
                             case InputMethodManager.RESULT_UNCHANGED_SHOWN:
                                 setKeyboardVisibility(true, System.nanoTime());
+                                if (m_softInputMode == 0) {
+                                    // probe for real keyboard height
+                                    m_layout.postDelayed(new Runnable() {
+                                            @Override
+                                            public void run() {
+                                                if (!m_keyboardIsVisible)
+                                                    return;
+                                                DisplayMetrics metrics = new DisplayMetrics();
+                                                m_activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
+                                                Rect r = new Rect();
+                                                m_activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(r);
+                                                if (metrics.heightPixels != r.bottom) {
+                                                    if (metrics.widthPixels > metrics.heightPixels) { // landscape
+                                                        if (m_landscapeKeyboardHeight != r.bottom) {
+                                                            m_landscapeKeyboardHeight = r.bottom;
+                                                            showSoftwareKeyboard(x, y, width, height, inputHints, enterKeyType);
+                                                        }
+                                                    } else {
+                                                        if (m_portraitKeyboardHeight != r.bottom) {
+                                                            m_portraitKeyboardHeight = r.bottom;
+                                                            showSoftwareKeyboard(x, y, width, height, inputHints, enterKeyType);
+                                                        }
+                                                    }
+                                                } else {
+                                                    // no luck ?
+                                                    // maybe the delay was too short, so let's make it longer
+                                                    if (m_probeKeyboardHeightDelay < 1000)
+                                                        m_probeKeyboardHeightDelay *= 2;
+                                                }
+                                            }
+                                        }, m_probeKeyboardHeightDelay);
+                                    }
                                 break;
                             case InputMethodManager.RESULT_HIDDEN:
                             case InputMethodManager.RESULT_UNCHANGED_HIDDEN: