Add event support for attribute value changed as well as modifier cha…

…nges
gurkenlabs · Dec 8, 2024 · 317830b · 317830b
1 parent 39f4240
commit 317830b
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Showing 7 changed files with 171 additions and 55 deletions.
diff --git a/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/Attribute.java b/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/Attribute.java
@@ -1,8 +1,10 @@
 package de.gurkenlabs.litiengine.attributes;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * An attribute is a numerical representation of a property that can be adjusted using {@link AttributeModifier}s.
@@ -11,70 +13,82 @@
  * registered modifications. This is e.g. useful when a property might only be changed for a certain period of time or
  * we need to know the original value of a property.
  * </p>
- * 
+ *
  * <p>
  * <i> An example use-case are player stats that might be affected throughout the game (e.g. via certain skills,
  * upgrades or level-ups). </i>
  * </p>
  *
- * @param <T>
- *          The type of the attribute value.
+ * @param <T> The type of the attribute value.
  */
 public class Attribute<T extends Number> {
-
   private final List<AttributeModifier<T>> modifiers;
+  private final Collection<AttributeValueListener> listeners = ConcurrentHashMap.newKeySet();
+  private final AttributeModifierListener attributeModifierListener = this::evaluateValue;
 
   private T baseValue;
 
+  private T value;
+
   /**
    * Initializes a new instance of the {@code Attribute} class.
    *
-   * @param initialValue
-   *          The initial value
+   * @param initialValue The initial value
    */
   public Attribute(final T initialValue) {
     this.modifiers = new ArrayList<>();
     this.baseValue = initialValue;
+    this.value = this.applyModifiers(this.getBase());
   }
 
   /**
    * Adds the specified modifier to this attribute.
-   * 
-   * @param modifier
-   *          The modifier to be added to this instance.
+   *
+   * @param modifier The modifier to be added to this instance.
    */
   public void addModifier(final AttributeModifier<T> modifier) {
     if (this.getModifiers().contains(modifier)) {
       return;
     }
 
     this.getModifiers().add(modifier);
+    modifier.onChanged(attributeModifierListener);
     Collections.sort(this.getModifiers());
+    this.evaluateValue();
+  }
+
+  public void onValueChanged(AttributeValueListener listener) {
+    this.listeners.add(listener);
+  }
+
+  public void removeListener(AttributeValueListener listener) {
+    this.listeners.add(listener);
   }
 
   /**
    * Removes the specified modifier from this attribute.
-   * 
-   * @param modifier
-   *          The modifier to be removed from this instance.
+   *
+   * @param modifier The modifier to be removed from this instance.
    */
   public void removeModifier(final AttributeModifier<T> modifier) {
     this.getModifiers().remove(modifier);
+    modifier.removeListener(attributeModifierListener);
     Collections.sort(this.getModifiers());
+    this.evaluateValue();
   }
 
   /**
    * Gets the current value of this attribute, respecting all the registered {@code AttributeModifier}s.
-   * 
+   *
    * @return The current value of this attribute.
    */
   public T get() {
-    return this.applyModifiers(this.getBase());
+    return this.value;
   }
 
   /**
    * Gets the raw base value of this attribute without applying any modifications.
-   * 
+   *
    * @return The raw base value of this attribute.
    */
   public T getBase() {
@@ -83,7 +97,7 @@ public T getBase() {
 
   /**
    * Gets all modifiers added to this instance.
-   * 
+   *
    * @return All modifiers added to this instance.
    */
   public List<AttributeModifier<T>> getModifiers() {
@@ -92,9 +106,8 @@ public List<AttributeModifier<T>> getModifiers() {
 
   /**
    * Determines whether the specified modifier instance is added to this attribute instance.
-   * 
-   * @param modifier
-   *          The modifier to check for.
+   *
+   * @param modifier The modifier to check for.
    * @return True if the modifier was added to this attribute instance; otherwise false.
    */
   public boolean isModifierApplied(final AttributeModifier<T> modifier) {
@@ -103,44 +116,48 @@ public boolean isModifierApplied(final AttributeModifier<T> modifier) {
 
   /**
    * Adjusts the base value of this attribute once with the specified modifier.
-   * 
-   * @param modifier
-   *          The modifier used to adjust this attribute's base value.
-   * 
+   *
+   * @param modifier The modifier used to adjust this attribute's base value.
    * @see #getBase()
    * @see #setBaseValue(Number)
    */
   public void modifyBaseValue(final AttributeModifier<T> modifier) {
-    this.baseValue = modifier.modify(this.getBase());
+    this.setBaseValue(modifier.modify(this.getBase()));
   }
 
   /**
    * Adjusts the base value of this attribute once with the specified modifier.
    *
-   * @param modification
-   *          The modification type.
-   * @param value
-   *          The modification value to be applied.
+   * @param modification The modification type.
+   * @param value        The modification value to be applied.
    */
   public void modifyBaseValue(final Modification modification, double value) {
-    this.baseValue = new AttributeModifier<T>(modification, value).modify(this.getBase());
+    this.modifyBaseValue(new AttributeModifier<>(modification, value));
   }
 
   /**
    * Sets the base value of this attribute.
-   * 
-   * @param baseValue
-   *          The base value to be set.
+   *
+   * @param baseValue The base value to be set.
    */
   public void setBaseValue(final T baseValue) {
     this.baseValue = baseValue;
+    this.evaluateValue();
+  }
+
+  protected void evaluateValue() {
+    final T previousValue = this.value;
+    this.value = this.applyModifiers(this.getBase());
+
+    if (previousValue != null && !previousValue.equals(this.value)) {
+      this.fireValueChangedEvent();
+    }
   }
 
   /**
    * Apply modifiers.
    *
-   * @param baseValue
-   *          the base value
+   * @param baseValue the base value
    * @return the t
    */
   protected T applyModifiers(final T baseValue) {
@@ -152,6 +169,12 @@ protected T applyModifiers(final T baseValue) {
     return currentValue;
   }
 
+  private void fireValueChangedEvent() {
+    for (var listener : this.listeners) {
+      listener.valueChanged();
+    }
+  }
+
   @Override
   public String toString() {
     return this.get() == null ? null : this.get().toString();

diff --git a/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/AttributeModifier.java b/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/AttributeModifier.java
@@ -1,5 +1,9 @@
 package de.gurkenlabs.litiengine.attributes;
 
+
+import java.util.Collection;
+import java.util.concurrent.ConcurrentHashMap;
+
 /**
  * An attribute modifier allows to modify attributes by the specified Modification and modify value.
  *
@@ -8,6 +12,7 @@
  * @see Attribute#modifyBaseValue(AttributeModifier)
  */
 public class AttributeModifier<T extends Number> implements Comparable<AttributeModifier<T>> {
+  private final Collection<AttributeModifierListener> listeners = ConcurrentHashMap.newKeySet();
   private final Modification modification;
   private double modifyValue;
   private boolean active;
@@ -50,14 +55,12 @@ public boolean equals(Object obj) {
     return super.equals(obj);
   }
 
-  /**
-   * Generates a hash code for this attribute modifier.
-   *
-   * @return The hash code.
-   */
-  @Override
-  public int hashCode() {
-    return super.hashCode();
+  public void onChanged(AttributeModifierListener listener) {
+    this.listeners.add(listener);
+  }
+
+  public void removeListener(AttributeModifierListener listener) {
+    this.listeners.add(listener);
   }
 
   /**
@@ -114,7 +117,12 @@ public T modify(final T modvalue) {
    * @param value The new modify value.
    */
   public void setModifyValue(double value) {
+    var previous = this.modifyValue;
     this.modifyValue = value;
+
+    if (previous != this.modifyValue) {
+      this.fireChangedEvent();
+    }
   }
 
   /**
@@ -123,7 +131,12 @@ public void setModifyValue(double value) {
    * @param active True to activate, false to deactivate.
    */
   public void setActive(boolean active) {
+    var previous = this.active;
     this.active = active;
+
+    if (previous != this.active) {
+      this.fireChangedEvent();
+    }
   }
 
   @SuppressWarnings("unchecked")
@@ -144,4 +157,10 @@ private T ensureType(final Double modValue, final T originalValue) {
 
     return null;
   }
+
+  private void fireChangedEvent() {
+    for (var listener : this.listeners) {
+      listener.modifierChanged();
+    }
+  }
 }
diff --git a/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/AttributeModifierListener.java b/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/AttributeModifierListener.java
@@ -0,0 +1,8 @@
+package de.gurkenlabs.litiengine.attributes;
+
+import java.util.EventListener;
+
+@FunctionalInterface
+public interface AttributeModifierListener extends EventListener {
+  void modifierChanged();
+}
diff --git a/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/AttributeValueListener.java b/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/AttributeValueListener.java
@@ -0,0 +1,8 @@
+package de.gurkenlabs.litiengine.attributes;
+
+import java.util.EventListener;
+
+@FunctionalInterface
+public interface AttributeValueListener extends EventListener {
+  void valueChanged();
+}
diff --git a/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/RangeAttribute.java b/litiengine/src/main/java/de/gurkenlabs/litiengine/attributes/RangeAttribute.java
@@ -8,8 +8,9 @@ public class RangeAttribute<T extends Number> extends Attribute<T> {
   private final List<AttributeModifier<T>> minModifiers;
   private final List<AttributeModifier<T>> maxModifiers;
   private T minBaseValue;
-
   private T maxBaseValue;
+  private T minValue;
+  private T maxValue;
 
   /**
    * Initializes a new instance of the {@code RangeAttribute} class.
@@ -28,6 +29,7 @@ public RangeAttribute(final T maxValue, final T minValue, final T baseValue) {
     this.maxModifiers = new CopyOnWriteArrayList<>();
     this.maxBaseValue = maxValue;
     this.minBaseValue = minValue;
+    this.evaluateValue();
   }
 
   public void addMinModifier(final AttributeModifier<T> modifier) {
@@ -37,6 +39,7 @@ public void addMinModifier(final AttributeModifier<T> modifier) {
 
     this.getMinModifiers().add(modifier);
     Collections.sort(this.getMinModifiers());
+    this.evaluateValue();
   }
 
   public void addMaxModifier(final AttributeModifier<T> modifier) {
@@ -46,20 +49,20 @@ public void addMaxModifier(final AttributeModifier<T> modifier) {
 
     this.getMaxModifiers().add(modifier);
     Collections.sort(this.getMaxModifiers());
+    this.evaluateValue();
   }
 
   @Override
   public T get() {
-    final T current = this.applyModifiers(this.getBase());
-    return this.valueInRange(current);
+    return this.valueInRange(super.get());
   }
 
   public T getMin() {
-    return this.applyMinModifiers(this.minBaseValue);
+    return this.minValue;
   }
 
   public T getMax() {
-    return this.applyMaxModifiers(this.maxBaseValue);
+    return this.maxValue;
   }
 
   public float getRelativeCurrentValue() {
@@ -69,10 +72,12 @@ public float getRelativeCurrentValue() {
   @Override
   public void modifyBaseValue(final AttributeModifier<T> modifier) {
     this.setBaseValue(this.valueInRange(modifier.modify(this.getBase())));
+    this.evaluateValue();
   }
 
   public void modifyMaxBaseValue(final AttributeModifier<T> modifier) {
     this.maxBaseValue = modifier.modify(this.maxBaseValue);
+    this.evaluateValue();
   }
 
   public void setToMin() {
@@ -85,10 +90,12 @@ public void setToMax() {
 
   public void setMaxBaseValue(final T maxValue) {
     this.maxBaseValue = maxValue;
+    this.evaluateValue();
   }
 
   public void setMinBaseValue(final T minValue) {
     this.minBaseValue = minValue;
+    this.evaluateValue();
   }
 
   protected List<AttributeModifier<T>> getMinModifiers() {
@@ -117,9 +124,16 @@ protected T applyMaxModifiers(final T maxValue) {
     return currentValue;
   }
 
+  @Override
+  protected void evaluateValue() {
+    super.evaluateValue();
+    this.minValue = this.applyMinModifiers(this.minBaseValue);
+    this.maxValue = this.applyMaxModifiers(this.maxBaseValue);
+  }
+
   private T valueInRange(final T value) {
-    if (value.doubleValue() < this.minBaseValue.doubleValue()) {
-      return this.minBaseValue;
+    if (value.doubleValue() < this.getMin().doubleValue()) {
+      return this.getMin();
     } else if (value.doubleValue() > this.getMax().doubleValue()) {
       return this.getMax();
     }