implement View.onInterceptTouchEvent() callback

This is needed to support nested scrolling

A second GtkEventControllerLegacy gets registerd with GTK_PHASE_CAPTURE

src/api-impl-jni/generated_headers/android_view_View.h

@@ -311,6 +311,14 @@ JNIEXPORT void JNICALL Java_android_view_View_setBackgroundColor
 JNIEXPORT void JNICALL Java_android_view_View_native_1setVisibility
   (JNIEnv *, jobject, jlong, jint, jfloat);
 
+/*
+ * Class:     android_view_View
+ * Method:    native_getGlobalVisibleRect
+ * Signature: (JLandroid/graphics/Rect;)Z
+ */
+JNIEXPORT jboolean JNICALL Java_android_view_View_native_1getGlobalVisibleRect
+  (JNIEnv *, jobject, jlong, jobject);
+
 #ifdef __cplusplus
 }
 #endif

src/api-impl-jni/util.c

@@ -118,6 +118,7 @@ void set_up_handle_cache(JNIEnv *env)
 	handle_cache.view.getScrollY = _METHOD(handle_cache.view.class, "getScrollY", "()I");
 	handle_cache.view.performClick = _METHOD(handle_cache.view.class, "performClick", "()Z");
 	handle_cache.view.onTouchEvent = _METHOD(handle_cache.view.class, "onTouchEvent", "(Landroid/view/MotionEvent;)Z");
+	handle_cache.view.onInterceptTouchEvent = _METHOD(handle_cache.view.class, "onInterceptTouchEvent", "(Landroid/view/MotionEvent;)Z");
 	handle_cache.view.layoutInternal = _METHOD(handle_cache.view.class, "layoutInternal", "(II)V");
 	handle_cache.view.measure = _METHOD(handle_cache.view.class, "measure", "(II)V");
 

src/api-impl-jni/util.h

@@ -71,6 +71,7 @@ struct handle_cache {
 		jmethodID getScrollY;
 		jmethodID performClick;
 		jmethodID onTouchEvent;
+		jmethodID onInterceptTouchEvent;
 		jmethodID layoutInternal;
 		jmethodID measure;
 	} view;

src/api-impl-jni/views/android_view_View.c

@@ -1,4 +1,5 @@
 #include <gtk/gtk.h>
+#include <stdio.h>
 
 #include "../defines.h"
 #include "../util.h"
@@ -10,9 +11,9 @@
 
 #define SOURCE_TOUCHSCREEN 0x1002
 
-struct touch_callback_data { JavaVM *jvm; jobject this; jobject on_touch_listener; jclass on_touch_listener_class;};
+struct touch_callback_data { JavaVM *jvm; jobject this; jobject on_touch_listener; jclass on_touch_listener_class; bool intercepted; };
 
-static bool call_ontouch_callback(int action, double x, double y, struct touch_callback_data *d)
+static bool call_ontouch_callback(int action, double x, double y, struct touch_callback_data *d, GtkPropagationPhase phase)
 {
 	bool ret;
 	JNIEnv *env;
@@ -20,8 +21,10 @@ static bool call_ontouch_callback(int action, double x, double y, struct touch_c
 
 	jobject motion_event = (*env)->NewObject(env, handle_cache.motion_event.class, handle_cache.motion_event.constructor, SOURCE_TOUCHSCREEN, action, (float)x, (float)y);
 
-	/* NULL listener means the callback was registered for onTouchEvent */
+	if (phase == GTK_PHASE_CAPTURE && !d->intercepted) {
-	if(d->on_touch_listener)
+		d->intercepted = (*env)->CallBooleanMethod(env, d->this, handle_cache.view.onInterceptTouchEvent, motion_event);
+		ret = d->intercepted;
+	} else if(d->on_touch_listener) /* NULL listener means the callback was registered for onTouchEvent */
 		ret = (*env)->CallBooleanMethod(env, d->on_touch_listener, _METHOD(d->on_touch_listener_class, "onTouch", "(Landroid/view/View;Landroid/view/MotionEvent;)Z"), d->this, motion_event);
 	else
 		ret = (*env)->CallBooleanMethod(env, d->this, _METHOD(d->on_touch_listener_class, "onTouchEvent", "(Landroid/view/MotionEvent;)Z"), motion_event);
@@ -30,6 +33,9 @@ static bool call_ontouch_callback(int action, double x, double y, struct touch_c
 		(*env)->ExceptionDescribe(env);
 
 	(*env)->DeleteLocalRef(env, motion_event);
+
+	if (action == MOTION_EVENT_ACTION_UP)
+		d->intercepted = false;
 	return ret;
 }
 static void gdk_event_get_widget_relative_position(GdkEvent *event, GtkWidget *widget, double *x, double *y)
@@ -49,25 +55,26 @@ static gboolean on_event(GtkEventControllerLegacy *event_controller, GdkEvent *e
 	double y;
 
 	GtkWidget *widget = gtk_event_controller_get_widget(GTK_EVENT_CONTROLLER(event_controller));
+	GtkPropagationPhase phase = gtk_event_controller_get_propagation_phase(GTK_EVENT_CONTROLLER(event_controller));
 
 	// TODO: this doesn't work for multitouch
 	switch(gdk_event_get_event_type(event)) {
 		case GDK_BUTTON_PRESS:
 		case GDK_TOUCH_BEGIN:
 			gdk_event_get_widget_relative_position(event, widget, &x, &y);
-			return call_ontouch_callback(MOTION_EVENT_ACTION_DOWN, x, y, d);
+			return call_ontouch_callback(MOTION_EVENT_ACTION_DOWN, x, y, d, phase);
 			break;
 		case GDK_BUTTON_RELEASE:
 		case GDK_TOUCH_END:
 			gdk_event_get_widget_relative_position(event, widget, &x, &y);
-			return call_ontouch_callback(MOTION_EVENT_ACTION_UP, x, y, d);
+			return call_ontouch_callback(MOTION_EVENT_ACTION_UP, x, y, d, phase);
 			break;
 		case GDK_MOTION_NOTIFY:
 			if (!(gdk_event_get_modifier_state(event) & GDK_BUTTON1_MASK))
 				break;
 		case GDK_TOUCH_UPDATE:
 			gdk_event_get_widget_relative_position(event, widget, &x, &y);
-			return call_ontouch_callback(MOTION_EVENT_ACTION_MOVE, x, y, d);
+			return call_ontouch_callback(MOTION_EVENT_ACTION_MOVE, x, y, d, phase);
 			break;
 		default:
 			break;
@@ -130,6 +137,20 @@ void _setOnTouchListener(JNIEnv *env, jobject this, GtkWidget *widget, jobject o
 	g_signal_connect(controller, "event", G_CALLBACK(on_event), callback_data);
 	gtk_widget_add_controller(widget, controller);
 	g_object_set_data(G_OBJECT(widget), "on_touch_listener", controller);
+
+	jmethodID onintercepttouchevent_method = _METHOD(_CLASS(this), "onInterceptTouchEvent", "(Landroid/view/MotionEvent;)Z");
+	if (onintercepttouchevent_method != handle_cache.view.onInterceptTouchEvent) {
+		GtkEventController *old_controller = g_object_get_data(G_OBJECT(widget), "on_intercept_touch_listener");
+		if(old_controller)
+			gtk_widget_remove_controller(widget, old_controller);
+
+		GtkEventController *controller = GTK_EVENT_CONTROLLER(gtk_event_controller_legacy_new());
+		gtk_event_controller_set_propagation_phase(controller, GTK_PHASE_CAPTURE);
+
+		g_signal_connect(controller, "event", G_CALLBACK(on_event), callback_data);
+		gtk_widget_add_controller(widget, controller);
+		g_object_set_data(G_OBJECT(widget), "on_intercept_touch_listener", controller);
+	}
 }
 
 JNIEXPORT void JNICALL Java_android_view_View_setOnTouchListener(JNIEnv *env, jobject this, jobject on_touch_listener)
@@ -418,3 +439,26 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1setBackgroundDrawable(JNIE
 	GdkPaintable *paintable = GDK_PAINTABLE(_PTR(paintable_ptr));
 	wrapper_widget_set_background(WRAPPER_WIDGET(gtk_widget_get_parent(widget)), paintable);
 }
+
+JNIEXPORT jboolean JNICALL Java_android_view_View_native_1getGlobalVisibleRect(JNIEnv *env, jobject this, jlong widget_ptr, jobject rect) {
+	GtkWidget *widget = GTK_WIDGET(_PTR(widget_ptr));
+	graphene_point_t point_in = {0, 0};
+	graphene_point_t point_out;
+	double off_x;
+	double off_y;
+	gboolean ret;
+	GtkWidget *window = GTK_WIDGET(gtk_widget_get_native(widget));
+	gtk_native_get_surface_transform(GTK_NATIVE(window), &off_x, &off_y);
+	ret = gtk_widget_compute_point(widget, window, &point_in, &point_out);
+	if (!ret)
+		return false;
+	_SET_INT_FIELD(rect, "left", point_out.x - off_x);
+	_SET_INT_FIELD(rect, "top", point_out.y - off_y);
+	point_in = (graphene_point_t){gtk_widget_get_width(widget), gtk_widget_get_height(widget)};
+	ret = gtk_widget_compute_point(widget, window, &point_in, &point_out);
+	if (!ret)
+		return false;
+	_SET_INT_FIELD(rect, "right", point_out.x - off_x);
+	_SET_INT_FIELD(rect, "bottom", point_out.y - off_y);
+	return true;
+}

src/api-impl/android/view/MotionEvent.java

@@ -1547,6 +1547,9 @@ public final class MotionEvent extends InputEvent {
 //							 0, 0, xPrecision, yPrecision,
 //							 downTime * NS_PER_MS, eventTime * NS_PER_MS,
 //							 1, pp, pc);
+			ev.action = action;
+			ev.coord_x = x;
+			ev.coord_y = y;
 			return ev;
 		}
 	}
@@ -2693,7 +2696,8 @@ public final class MotionEvent extends InputEvent {
 	 * @see #EDGE_BOTTOM
 	 */
 	public final int getEdgeFlags() {
-		return nativeGetEdgeFlags(mNativePtr);
+		// return nativeGetEdgeFlags(mNativePtr);
+		return 0;
 	}
 
 	/**

src/api-impl/android/view/VelocityTracker.java

@@ -11,6 +11,7 @@ public class VelocityTracker {
 	public void recycle() {}
 
 	public void computeCurrentVelocity(int units, float maxVelocity) {}
+	public void computeCurrentVelocity(int units) {}
 
 	public float getXVelocity(int id) {return 0.f;}
 	public float getYVelocity(int id) {return 0.f;}

src/api-impl/android/view/View.java

@@ -1623,4 +1623,16 @@ public class View extends Object {
 	}
 
 	public void removeOnAttachStateChangeListener(OnAttachStateChangeListener listener) {}
+
+	public boolean onInterceptTouchEvent(MotionEvent event) {return false;}
+
+	public boolean dispatchTouchEvent(MotionEvent event) {return false;}
+
+	public boolean canScrollHorizontally(int direction) {return false;}
+
+	protected native boolean native_getGlobalVisibleRect(long widget, Rect visibleRect);
+
+	public boolean getGlobalVisibleRect(Rect visibleRect) {
+		return native_getGlobalVisibleRect(widget, visibleRect);
+	}
 }