Add SDL Pinch events (#9445)

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

@@ -1084,6 +1084,9 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
     public static native boolean nativeAllowRecreateActivity();
     public static native int nativeCheckSDLThreadCounter();
     public static native void onNativeFileDialog(int requestCode, String[] filelist, int filter);
+    public static native void onNativePinchStart();
+    public static native void onNativePinchUpdate(float scale);
+    public static native void onNativePinchEnd();
 
     /**
      * This method is called by SDL using JNI.

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

@@ -23,6 +23,7 @@ import android.view.View;
 import android.view.WindowInsets;
 import android.view.WindowManager;
 
+import android.view.ScaleGestureDetector;
 
 /**
     SDLSurface. This is what we draw on, so we need to know when it's created
@@ -31,7 +32,8 @@ import android.view.WindowManager;
     Because of this, that's where we set up the SDL thread
 */
 public class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
-    View.OnApplyWindowInsetsListener, View.OnKeyListener, View.OnTouchListener, SensorEventListener  {
+    View.OnApplyWindowInsetsListener, View.OnKeyListener, View.OnTouchListener,
+    SensorEventListener, ScaleGestureDetector.OnScaleGestureListener {
 
     // Sensors
     protected SensorManager mSensorManager;
@@ -43,11 +45,16 @@ public class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
     // Is SurfaceView ready for rendering
     protected boolean mIsSurfaceReady;
 
+    // Pinch events
+    private final ScaleGestureDetector scaleGestureDetector;
+
     // Startup
     protected SDLSurface(Context context) {
         super(context);
         getHolder().addCallback(this);
 
+        scaleGestureDetector = new ScaleGestureDetector(context, this);
+
         setFocusable(true);
         setFocusableInTouchMode(true);
         requestFocus();
@@ -294,6 +301,8 @@ public class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
                 break;
         } while (++i < pointerCount);
 
+        scaleGestureDetector.onTouchEvent(event);
+
         return true;
     }
 
@@ -415,4 +424,23 @@ public class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
 
         return false;
     }
+
+    @Override
+    public boolean onScale(ScaleGestureDetector detector) {
+        float scale = detector.getScaleFactor();
+        SDLActivity.onNativePinchUpdate(scale);
+        return true;
+    }
+
+    @Override
+    public boolean onScaleBegin(ScaleGestureDetector detector) {
+        SDLActivity.onNativePinchStart();
+        return true;
+    }
+
+    @Override
+    public void onScaleEnd(ScaleGestureDetector detector) {
+        SDLActivity.onNativePinchEnd();
+    }
+
 }