Added support for the third stylus button on Android

android-project/app/src/main/java/org/libsdl/app/SDLControllerManager.java

@@ -755,6 +755,9 @@ class SDLGenericMotionListener_API14 implements View.OnGenericMotionListener {
 
                         // BUTTON_STYLUS_PRIMARY is 2^5, so shift by 4, and apply SDL_PEN_INPUT_DOWN/SDL_PEN_INPUT_ERASER_TIP
                         int buttons = (event.getButtonState() >> 4) | (1 << (toolType == MotionEvent.TOOL_TYPE_STYLUS ? 0 : 30));
+                        if ((event.getButtonState() & MotionEvent.BUTTON_TERTIARY) != 0) {
+                            buttons |= 0x08;
+                        }
 
                         SDLActivity.onNativePen(event.getPointerId(i), getPenDeviceType(event.getDevice()), buttons, action, x, y, p);
                         consumed = true;

android-project/app/src/main/java/org/libsdl/app/SDLSurface.java

@@ -280,6 +280,9 @@ public class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
 
                 // BUTTON_STYLUS_PRIMARY is 2^5, so shift by 4, and apply SDL_PEN_INPUT_DOWN/SDL_PEN_INPUT_ERASER_TIP
                 int buttonState = (event.getButtonState() >> 4) | (1 << (toolType == MotionEvent.TOOL_TYPE_STYLUS ? 0 : 30));
+                if ((event.getButtonState() & MotionEvent.BUTTON_TERTIARY) != 0) {
+                    buttonState |= 0x08;
+                }
 
                 SDLActivity.onNativePen(pointerId, SDLActivity.getMotionListener().getPenDeviceType(event.getDevice()), buttonState, action, x, y, p);
             } else { // MotionEvent.TOOL_TYPE_FINGER or MotionEvent.TOOL_TYPE_UNKNOWN

src/video/android/SDL_androidpen.c

@@ -66,12 +66,12 @@ void Android_OnPen(SDL_Window *window, int pen_id_in, SDL_PenDeviceType device_t
     SDL_PenInputFlags current = SDL_GetPenStatus(pen, NULL, 0);
     int diff = current ^ button;
     if (diff != 0) {
-        // Android only exposes BUTTON_STYLUS_PRIMARY and BUTTON_STYLUS_SECONDARY
-        if (diff & SDL_PEN_INPUT_BUTTON_1)
-            SDL_SendPenButton(0, pen, window, 1, (button & SDL_PEN_INPUT_BUTTON_1) != 0);
-
-        if (diff & SDL_PEN_INPUT_BUTTON_2)
-            SDL_SendPenButton(0, pen, window, 2, (button & SDL_PEN_INPUT_BUTTON_2) != 0);
+        for (Uint8 i = 1; i <= 5; ++i) {
+            Uint8 mask = (1 << i);
+            if (diff & mask) {
+                SDL_SendPenButton(0, pen, window, i, (button & mask) != 0);
+            }
+        }
     }
 
     // button contains DOWN/ERASER_TIP on DOWN/UP regardless of pressed state, use action to distinguish