feat(android): expose secondary-screen touch events

mobile/android/love/src/jni/love/src/common/android.cpp

@@ -1003,4 +1003,33 @@ void love_android_secondary_enable(int on)
 	env->DeleteLocalRef(activity);
 }
 
+extern "C" __attribute__((visibility("default")))
+const char *love_android_poll_secondary_touch()
+{
+	static thread_local std::string event;
+	event.clear();
+	JNIEnv *env = (JNIEnv*) SDL_AndroidGetJNIEnv();
+	jclass activity = env->FindClass("org/love2d/android/GameActivity");
+	jmethodID method = env->GetStaticMethodID(activity, "pollSecondaryDisplayTouch",
+		"()Ljava/lang/String;");
+	if (!method)
+		env->ExceptionClear();
+	else
+	{
+		jstring value = (jstring) env->CallStaticObjectMethod(activity, method);
+		if (value)
+		{
+			const char *utf = env->GetStringUTFChars(value, nullptr);
+			if (utf)
+			{
+				event = utf;
+				env->ReleaseStringUTFChars(value, utf);
+			}
+			env->DeleteLocalRef(value);
+		}
+	}
+	env->DeleteLocalRef(activity);
+	return event.empty() ? nullptr : event.c_str();
+}
+
 #endif // LOVE_ANDROID

mobile/android/love/src/main/java/org/love2d/android/GameActivity.java

@@ -1325,6 +1325,9 @@ public class GameActivity extends SDLActivity {
     // in src/jni/love/src/common/android.cpp.
     private static volatile SecondaryPresentation secondaryPresentation;
     private static volatile boolean secondaryEnabled = false;
+    private static final int MAX_SECONDARY_TOUCHES = 32;
+    private static final java.util.ArrayDeque<String> secondaryTouches =
+        new java.util.ArrayDeque<>();
 
     @Keep
     public static void setSecondaryEnabled(final boolean on) {
@@ -1377,6 +1380,7 @@ public class GameActivity extends SDLActivity {
     private static void teardownSecondaryDisplay() {
         SecondaryPresentation p = secondaryPresentation;
         secondaryPresentation = null;
+        synchronized (secondaryTouches) { secondaryTouches.clear(); }
         if (p != null) {
             try { p.dismiss(); } catch (Throwable t) {}
         }
@@ -1395,6 +1399,13 @@ public class GameActivity extends SDLActivity {
         }
     }
 
+    @Keep
+    public static String pollSecondaryDisplayTouch() {
+        synchronized (secondaryTouches) {
+            return secondaryTouches.pollFirst();
+        }
+    }
+
     private static class SecondaryPresentation extends android.app.Presentation {
         private final FrameView frameView;
 
@@ -1461,6 +1472,7 @@ public class GameActivity extends SDLActivity {
         private final android.graphics.Paint paint = new android.graphics.Paint();
         private final Object lock = new Object();
         private int fw, fh;
+        private int activePointer = -1;
 
         FrameView(Context context) {
             super(context);
@@ -1482,6 +1494,52 @@ public class GameActivity extends SDLActivity {
             postInvalidate();
         }
 
+        private void enqueueTouch(String event) {
+            synchronized (secondaryTouches) {
+                if (secondaryTouches.size() >= MAX_SECONDARY_TOUCHES) {
+                    secondaryTouches.clear();
+                    secondaryTouches.addLast("cancel,0,0");
+                } else {
+                    secondaryTouches.addLast(event);
+                }
+            }
+        }
+
+        private int logicalX(float x) {
+            return Math.min(fw - 1, Math.max(0,
+                (int) ((x - dst.left) * fw / dst.width())));
+        }
+
+        private int logicalY(float y) {
+            return Math.min(fh - 1, Math.max(0,
+                (int) ((y - dst.top) * fh / dst.height())));
+        }
+
+        @Override
+        public boolean onTouchEvent(android.view.MotionEvent event) {
+            synchronized (lock) {
+                int action = event.getActionMasked();
+                if (action == android.view.MotionEvent.ACTION_DOWN && fw > 0
+                        && dst.contains((int) event.getX(), (int) event.getY())) {
+                    activePointer = event.getPointerId(0);
+                    enqueueTouch("down," + logicalX(event.getX()) + ","
+                        + logicalY(event.getY()));
+                } else if (action == android.view.MotionEvent.ACTION_UP
+                        && activePointer >= 0) {
+                    int index = event.findPointerIndex(activePointer);
+                    if (index >= 0 && fw > 0) {
+                        enqueueTouch("up," + logicalX(event.getX(index)) + ","
+                            + logicalY(event.getY(index)));
+                    }
+                    activePointer = -1;
+                } else if (action == android.view.MotionEvent.ACTION_CANCEL) {
+                    activePointer = -1;
+                    enqueueTouch("cancel,0,0");
+                }
+            }
+            return true;
+        }
+
         @Override
         protected void onDraw(android.graphics.Canvas canvas) {
             synchronized (lock) {