Reset MouseHandler upon refreshing (#47)

* fix(framework): MouseHandler hack * feat(framework): Make reflection elements static and use log instead of exception * refactor(framework): Move hack into util class --------- Co-authored-by: Adrian Kunz <[email protected]>
fujaba · Feb 23, 2024 · 4396f76 · 4396f76
1 parent 692356f
commit 4396f76
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diff --git a/framework/src/main/java/org/fulib/fx/FulibFxApp.java b/framework/src/main/java/org/fulib/fx/FulibFxApp.java
@@ -16,6 +16,7 @@
 import org.fulib.fx.dagger.DaggerFrameworkComponent;
 import org.fulib.fx.dagger.FrameworkComponent;
 import org.fulib.fx.util.ControllerUtil;
+import org.fulib.fx.util.ReflectionUtil;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.MustBeInvokedByOverriders;
 import org.jetbrains.annotations.NotNull;
@@ -324,7 +325,8 @@ public void refresh() {
         Map<String, Object> params = this.component.router().current().getValue(); // Use the same parameters as before
         this.component.controllerManager().init(currentMainController, params, true); // Re-initialize the controller
         Parent parent = this.component.controllerManager().render(currentMainController, params); // Re-render the controller
-        display(parent); // Display the controller
+        ReflectionUtil.resetMouseHandler(stage());
+        display(parent);
     }
 
     /**

diff --git a/framework/src/main/java/org/fulib/fx/util/ReflectionUtil.java b/framework/src/main/java/org/fulib/fx/util/ReflectionUtil.java
@@ -3,24 +3,40 @@
 import javafx.collections.ObservableList;
 import javafx.scene.Node;
 import javafx.scene.Parent;
+import javafx.scene.Scene;
+import javafx.stage.Stage;
+import org.fulib.fx.FulibFxApp;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import javax.inject.Provider;
-import java.lang.reflect.Field;
-import java.lang.reflect.Method;
-import java.lang.reflect.ParameterizedType;
-import java.lang.reflect.Type;
+import java.lang.reflect.*;
 
 /**
  * Utility class containing different helper methods for the framework or the user.
+ * Parts of this class are hacky and should be used with caution.
  */
 public class ReflectionUtil {
 
     private ReflectionUtil() {
         // Prevent instantiation
     }
 
+    // Reflection for mouse handler
+    private static Field mouseHandlerField;
+    private static Constructor<?> mouseHandlerCtor;
+
+    static {
+        try {
+            mouseHandlerField = Scene.class.getDeclaredField("mouseHandler");
+            mouseHandlerCtor = Class.forName(Scene.class.getName() + "$MouseHandler").getDeclaredConstructor(Scene.class);
+            mouseHandlerField.setAccessible(true);
+            mouseHandlerCtor.setAccessible(true);
+        } catch (ReflectiveOperationException e) {
+            FulibFxApp.LOGGER.severe("Could not initialize mouse handler reflection. This may cause problems with mouse drag events.");
+        }
+    }
+
     /**
      * Returns the class provided by the given provider field.
      *
@@ -86,4 +102,22 @@ public static Object getInstanceOfProviderField(Field provider, Object instance)
         }
     }
 
+    /**
+     * Resets the mouse handler of the given stage. This method is used to reset the mouse handler of a scene to avoid
+     * problems with mouse drag events. This should be used with caution and is mainly used for refreshing the scene.
+     *
+     * @param stage The stage to reset the mouse handler for
+     */
+    public static void resetMouseHandler(Stage stage) {
+        // NB: This hack avoids problems with mouse drag events.
+        // In particular, the scene's MouseHandler would keep a list of its previous nodes,
+        // which do not have a reference back to the scene and subsequently cause an NPE.
+        try {
+            final Scene scene = stage.getScene();
+            final Object mouseHandler = mouseHandlerCtor.newInstance(scene);
+            mouseHandlerField.set(scene, mouseHandler);
+        } catch (ReflectiveOperationException e) {
+            FulibFxApp.LOGGER.warning("Could not reset mouse handler. This may cause problems with mouse drag events after refreshing the scene.");
+        }
+    }
 }