feat(android): add tapjacking prevention features

- Added boolean property "filterTouchesWhenObscured" to all Ti.UI.View dervied types.
- Added event "touchfiltered" event to Ti.UI.Button.
- Added boolean property "obscured" to all touch related events.
  * Will only be true if "filterTouchesWhenObscured" is false.

Fixes TIMOB-28080

android/modules/ui/src/java/ti/modules/titanium/ui/widget/TiUIButton.java

@@ -27,6 +27,7 @@
 import android.graphics.drawable.Drawable;
 import android.text.TextUtils;
 import android.view.Gravity;
+import android.view.MotionEvent;
 import androidx.appcompat.widget.AppCompatButton;
 
 public class TiUIButton extends TiUIView
@@ -45,6 +46,16 @@ public TiUIButton(final TiViewProxy proxy)
 		super(proxy);
 		Log.d(TAG, "Creating a button", Log.DEBUG_MODE);
 		AppCompatButton btn = new AppCompatButton(proxy.getActivity()) {
+			@Override
+			public boolean onFilterTouchEventForSecurity(MotionEvent event)
+			{
+				boolean isTouchAllowed = super.onFilterTouchEventForSecurity(event);
+				if (!isTouchAllowed) {
+					fireEvent(TiC.EVENT_TOUCH_FILTERED, dictFromEvent(event));
+				}
+				return isTouchAllowed;
+			}
+
 			@Override
 			protected void onLayout(boolean changed, int left, int top, int right, int bottom)
 			{

android/titanium/src/java/org/appcelerator/titanium/TiC.java

@@ -370,6 +370,11 @@ public class TiC
 	 */
 	public static final String EVENT_PROPERTY_MESSAGE = "message";
 
+	/**
+	 * @module.api
+	 */
+	public static final String EVENT_PROPERTY_OBSCURED = "obscured";
+
 	/**
 	 * @module.api
 	 */
@@ -684,6 +689,11 @@ public class TiC
 	 */
 	public static final String EVENT_TOUCH_END = "touchend";
 
+	/**
+	 * @module.api
+	 */
+	public static final String EVENT_TOUCH_FILTERED = "touchfiltered";
+
 	/**
 	 * @module.api
 	 */
@@ -1687,6 +1697,11 @@ public class TiC
 	 */
 	public static final String PROPERTY_FILTER_CASE_INSENSITIVE = "filterCaseInsensitive";
 
+	/**
+	 * @module.api
+	 */
+	public static final String PROPERTY_FILTER_TOUCHES_WHEN_OBSCURED = "filterTouchesWhenObscured";
+
 	/**
 	 * @module.api
 	 */

android/titanium/src/java/org/appcelerator/titanium/proxy/TiViewProxy.java

@@ -79,6 +79,7 @@
 	// others
 	TiC.PROPERTY_FOCUSABLE,
 	TiC.PROPERTY_TOUCH_ENABLED,
+	TiC.PROPERTY_FILTER_TOUCHES_WHEN_OBSCURED,
 	TiC.PROPERTY_VISIBLE,
 	TiC.PROPERTY_ENABLED,
 	TiC.PROPERTY_OPACITY,
@@ -126,6 +127,7 @@ public TiViewProxy()
 		pendingAnimationLock = new Object();
 
 		defaultValues.put(TiC.PROPERTY_TOUCH_ENABLED, true);
+		defaultValues.put(TiC.PROPERTY_FILTER_TOUCHES_WHEN_OBSCURED, false);
 		defaultValues.put(TiC.PROPERTY_SOUND_EFFECTS_ENABLED, true);
 		defaultValues.put(TiC.PROPERTY_BACKGROUND_REPEAT, false);
 		defaultValues.put(TiC.PROPERTY_VISIBLE, true);

android/titanium/src/java/org/appcelerator/titanium/view/TiUIView.java

@@ -758,6 +758,8 @@ public void propertyChanged(String key, Object oldValue, Object newValue, KrollP
 		} else if (key.equals(TiC.PROPERTY_TOUCH_ENABLED)) {
 			nativeView.setEnabled(TiConvert.toBoolean(newValue));
 			doSetClickable(TiConvert.toBoolean(newValue));
+		} else if (key.equals(TiC.PROPERTY_FILTER_TOUCHES_WHEN_OBSCURED)) {
+			setFilterTouchesWhenObscured(TiConvert.toBoolean(newValue, false));
 		} else if (key.equals(TiC.PROPERTY_VISIBLE)) {
 			newValue = (newValue == null) ? false : newValue;
 			this.setVisibility(TiConvert.toBoolean(newValue) ? View.VISIBLE : View.INVISIBLE);
@@ -987,6 +989,11 @@ public void processProperties(KrollDict d)
 			applyTouchFeedback((colorString != null) ? TiConvert.toColor(colorString) : null);
 		}
 
+		if (d.containsKey(TiC.PROPERTY_FILTER_TOUCHES_WHEN_OBSCURED) && !nativeViewNull) {
+			setFilterTouchesWhenObscured(
+				TiConvert.toBoolean(d.get(TiC.PROPERTY_FILTER_TOUCHES_WHEN_OBSCURED), false));
+		}
+
 		if (d.containsKey(TiC.PROPERTY_HIDDEN_BEHAVIOR) && !nativeViewNull) {
 			Object hidden = d.get(TiC.PROPERTY_HIDDEN_BEHAVIOR);
 			if (hidden != null) {
@@ -1516,6 +1523,43 @@ private void handleBorderProperty(String property, Object value)
 		motionEvents.put(MotionEvent.ACTION_CANCEL, TiC.EVENT_TOUCH_CANCEL);
 	}
 
+	private void setFilterTouchesWhenObscured(boolean isEnabled)
+	{
+		// Validate.
+		if (this.nativeView == null) {
+			return;
+		}
+
+		// Enable/disable tapjacking filter.
+		this.nativeView.setFilterTouchesWhenObscured(isEnabled);
+
+		// Android 4.4.2 and older has a bug where the above method sets it to the opposite.
+		// Google fixed it in Android 4.4.3, but we can't detect that patch version via API Level.
+		if ((Build.VERSION.SDK_INT < 21) && (isEnabled != this.nativeView.getFilterTouchesWhenObscured())) {
+			this.nativeView.setFilterTouchesWhenObscured(!isEnabled);
+		}
+	}
+
+	/**
+	 * Determines if touch event was obscurred by an overlapping translucent window belonging to another app.
+	 * This is used for security purposes to detect "tapjacking".
+	 * @param event The touch event to be analyzed. Can be null.
+	 * @return Returns true if touch event was obscurred. Returns false if not or if given a null argument.
+	 */
+	private boolean wasObscured(MotionEvent event)
+	{
+		if (event != null) {
+			int flags = event.getFlags();
+			if ((flags & MotionEvent.FLAG_WINDOW_IS_OBSCURED) != 0) {
+				return true;
+			}
+			if ((Build.VERSION.SDK_INT >= 29) && ((flags & MotionEvent.FLAG_WINDOW_IS_PARTIALLY_OBSCURED) != 0)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 	protected KrollDict dictFromEvent(MotionEvent e)
 	{
 		TiDimension xDimension = new TiDimension((double) e.getX(), TiDimension.TYPE_LEFT);
@@ -1525,6 +1569,7 @@ protected KrollDict dictFromEvent(MotionEvent e)
 		data.put(TiC.EVENT_PROPERTY_X, xDimension.getAsDefault(this.nativeView));
 		data.put(TiC.EVENT_PROPERTY_Y, yDimension.getAsDefault(this.nativeView));
 		data.put(TiC.EVENT_PROPERTY_FORCE, (double) e.getPressure());
+		data.put(TiC.EVENT_PROPERTY_OBSCURED, wasObscured(e));
 		data.put(TiC.EVENT_PROPERTY_SIZE, (double) e.getSize());
 		data.put(TiC.EVENT_PROPERTY_SOURCE, proxy);
 		return data;
@@ -1548,6 +1593,11 @@ protected KrollDict dictFromEvent(KrollDict dictToCopy)
 		} else {
 			data.put(TiC.EVENT_PROPERTY_FORCE, (double) 0);
 		}
+		if (dictToCopy.containsKey(TiC.EVENT_PROPERTY_OBSCURED)) {
+			data.put(TiC.EVENT_PROPERTY_OBSCURED, dictToCopy.get(TiC.EVENT_PROPERTY_OBSCURED));
+		} else {
+			data.put(TiC.EVENT_PROPERTY_OBSCURED, false);
+		}
 		if (dictToCopy.containsKey(TiC.EVENT_PROPERTY_SIZE)) {
 			data.put(TiC.EVENT_PROPERTY_SIZE, dictToCopy.get(TiC.EVENT_PROPERTY_SIZE));
 		} else {
@@ -1708,6 +1758,7 @@ public boolean onTouch(View view, MotionEvent event)
 					TiDimension yDimension = new TiDimension((double) event.getY(), TiDimension.TYPE_TOP);
 					lastUpEvent.put(TiC.EVENT_PROPERTY_X, xDimension.getAsDefault(view));
 					lastUpEvent.put(TiC.EVENT_PROPERTY_Y, yDimension.getAsDefault(view));
+					lastUpEvent.put(TiC.EVENT_PROPERTY_OBSCURED, wasObscured(event));
 				}
 
 				if (proxy != null && proxy.hierarchyHasListener(TiC.EVENT_PINCH)) {

apidoc/Titanium/UI/Button.yml

@@ -96,6 +96,36 @@ excludes:
     properties: [children]
     methods: [add, remove, removeAllChildren, replaceAt]
 since: "0.8"
+
+events:
+  - name: touchfiltered
+    summary: Fired when the device detects a swipe gesture against the view.
+    description: |
+        If the button's [filterTouchesWhenObscured](Titanium.UI.View.filterTouchesWhenObscured) property
+        is set `true`, then this event will be fired if the touch event was discarded because another app's
+        overlapping window obscured it.
+
+        This is a security feature to protect an app from "tapjacking", where a malicious app can use a
+        system overlay to intercept touch events in your app or to trick the end-user to tap on UI
+        in your app intended for the overlay.
+
+        You can use this event to display an alert dialog explaining why the button's action has been disabled.
+        Especially if the overlapping window is completely invisible.
+    platforms: [android]
+    since: "9.3.0"
+    properties:
+      - name: x
+        summary: X coordinate of the event from the `source` view's coordinate system.
+        type: Number
+
+      - name: y
+        summary: Y coordinate of the event from the `source` view's coordinate system.
+        type: Number
+
+      - name: obscured
+        type: Boolean
+        summary: Always `true` since the touch event passed through another app's overlapping window.
+
 properties:
   - name: attributedString
     summary: Specify an attributed string for the label.