Android: Implement QInputMethod::keyboardRectangle

We can use getWindowVisibleDisplayFrame to know the height on the
keyboard, and we can use getLocationOnScreen to find out how much
the view is scrolled. Since onPreDraw is always called when the
view is scrolled or when the keyboard appears or disapear, we can
call the native functions from there.

This is not working for floating keyboards.

[ChangeLog][Android] Implemented QInputMethod::keyboardRectangle

Task-number: QTBUG-40731
Change-Id: I7848eb34fece410b29a06bf0bbb2313112fffa68
Reviewed-by: Samuel Nevala <samuel.nevala@intopalo.com>
Reviewed-by: BogDan Vatra <bogdan@kdab.com>

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

@@ -66,6 +66,8 @@ import android.view.ViewConfiguration;
 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;
@@ -859,6 +861,25 @@ public class QtActivityDelegate
 
         QtNative.handleOrientationChanged(rotation, m_nativeOrientation);
         m_currentRotation = rotation;
+
+        m_layout.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
+            @Override
+            public boolean onPreDraw() {
+                if (!m_keyboardIsVisible)
+                    return true;
+
+                Rect r = new Rect();
+                m_activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(r);
+                DisplayMetrics metrics = new DisplayMetrics();
+                m_activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
+                final int kbHeight = metrics.heightPixels - r.bottom;
+                final int[] location = new int[2];
+                m_layout.getLocationOnScreen(location);
+                QtNative.keyboardGeometryChanged(location[0], r.bottom - location[1],
+                                                 r.width(), kbHeight);
+                return true;
+            }
+        });
     }
 
     public void initializeAccessibility()

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

@@ -677,6 +677,7 @@ public class QtNative
     public static native void keyDown(int key, int unicode, int modifier, boolean autoRepeat);
     public static native void keyUp(int key, int unicode, int modifier, boolean autoRepeat);
     public static native void keyboardVisibilityChanged(boolean visibility);
+    public static native void keyboardGeometryChanged(int x, int y, int width, int height);
     // keyboard methods
 
     // dispatch events methods

src/gui/kernel/qinputmethod.cpp

@@ -147,6 +147,9 @@ QRectF QInputMethod::cursorRectangle() const
 /*!
     \property QInputMethod::keyboardRectangle
     \brief Virtual keyboard's geometry in window coordinates.
+
+    This might be an empty rectangle if it is not possible to know the geometry
+    of the keyboard. This is the case for a floating keyboard on android.
 */
 QRectF QInputMethod::keyboardRectangle() const
 {

src/plugins/platforms/android/androidjniinput.cpp

@@ -51,6 +51,7 @@ namespace QtAndroidInput
 
     static bool m_ignoreMouseEvents = false;
     static bool m_softwareKeyboardVisible = false;
+    static QRect m_softwareKeyboardRect;
 
     static QList<QWindowSystemInterface::TouchPoint> m_touchPoints;
 
@@ -108,6 +109,11 @@ namespace QtAndroidInput
         return m_softwareKeyboardVisible;
     }
 
+    QRect softwareKeyboardRect()
+    {
+        return m_softwareKeyboardRect;
+    }
+
 
     static void mouseDown(JNIEnv */*env*/, jobject /*thiz*/, jint /*winId*/, jint x, jint y)
     {
@@ -734,14 +740,35 @@ namespace QtAndroidInput
     static void keyboardVisibilityChanged(JNIEnv */*env*/, jobject /*thiz*/, jboolean visibility)
     {
         m_softwareKeyboardVisible = visibility;
+        if (!visibility)
+            m_softwareKeyboardRect = QRect();
+
         QAndroidInputContext *inputContext = QAndroidInputContext::androidInputContext();
-        if (inputContext && qGuiApp)
+        if (inputContext && qGuiApp) {
             inputContext->emitInputPanelVisibleChanged();
+            if (!visibility)
+                inputContext->emitKeyboardRectChanged();
+        }
 #ifdef QT_DEBUG_ANDROID_IM_PROTOCOL
         qDebug() << "@@@ KEYBOARDVISIBILITYCHANGED" << inputContext;
 #endif
     }
 
+    static void keyboardGeometryChanged(JNIEnv */*env*/, jobject /*thiz*/, jint x, jint y, jint w, jint h)
+    {
+        QRect r = QRect(x, y, w, h);
+        if (r == m_softwareKeyboardRect)
+            return;
+        m_softwareKeyboardRect = r;
+        QAndroidInputContext *inputContext = QAndroidInputContext::androidInputContext();
+        if (inputContext && qGuiApp)
+            inputContext->emitKeyboardRectChanged();
+
+#ifdef QT_DEBUG_ANDROID_IM_PROTOCOL
+        qDebug() << "@@@ KEYBOARDRECTCHANGED" << m_softwareKeyboardRect;
+#endif
+    }
+
     static JNINativeMethod methods[] = {
         {"touchBegin","(I)V",(void*)touchBegin},
         {"touchAdd","(IIIZIIFF)V",(void*)touchAdd},
@@ -753,7 +780,8 @@ namespace QtAndroidInput
         {"tabletEvent", "(IIJIIIFFF)V", (void *)tabletEvent},
         {"keyDown", "(IIIZ)V", (void *)keyDown},
         {"keyUp", "(IIIZ)V", (void *)keyUp},
-        {"keyboardVisibilityChanged", "(Z)V", (void *)keyboardVisibilityChanged}
+        {"keyboardVisibilityChanged", "(Z)V", (void *)keyboardVisibilityChanged},
+        {"keyboardGeometryChanged", "(IIII)V", (void *)keyboardGeometryChanged}
     };
 
     bool registerNatives(JNIEnv *env)

src/plugins/platforms/android/androidjniinput.h

@@ -35,6 +35,7 @@
 #define ANDROIDJNIINPUT_H
 #include <jni.h>
 #include <QtCore/qglobal.h>
+#include <QtCore/QRect>
 
 QT_BEGIN_NAMESPACE
 
@@ -45,6 +46,7 @@ namespace QtAndroidInput
     void resetSoftwareKeyboard();
     void hideSoftwareKeyboard();
     bool isSoftwareKeyboardVisible();
+    QRect softwareKeyboardRect();
     void updateSelection(int selStart, int selEnd, int candidatesStart, int candidatesEnd);
     // Software keyboard support
 

src/plugins/platforms/android/qandroidinputcontext.cpp

@@ -512,7 +512,7 @@ void QAndroidInputContext::invokeAction(QInputMethod::Action action, int cursorP
 
 QRectF QAndroidInputContext::keyboardRect() const
 {
-    return QPlatformInputContext::keyboardRect();
+    return QtAndroidInput::softwareKeyboardRect();
 }
 
 bool QAndroidInputContext::isAnimating() const