Add callback for selection in dropdown GUIs

src/main/java/de/johni0702/minecraft/gui/element/advanced/AbstractGuiDropdownMenu.java

@@ -32,6 +32,7 @@ import de.johni0702.minecraft.gui.element.AbstractGuiClickable;
 import de.johni0702.minecraft.gui.element.GuiElement;
 import de.johni0702.minecraft.gui.function.Clickable;
 import de.johni0702.minecraft.gui.layout.VerticalLayout;
+import de.johni0702.minecraft.gui.utils.Consumer;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import net.minecraft.client.gui.FontRenderer;
@@ -53,6 +54,8 @@ public abstract class AbstractGuiDropdownMenu<V, T extends AbstractGuiDropdownMe
     @Getter
     private boolean opened;
 
+    private Consumer<Integer> onSelection;
+
     private GuiPanel dropdown;
 
     private ReadableDimension size;
@@ -136,6 +139,7 @@ public abstract class AbstractGuiDropdownMenu<V, T extends AbstractGuiDropdownMe
     @Override
     public T setSelected(int selected) {
         this.selected = selected;
+        onSelection(selected);
         return getThis();
     }
 
@@ -165,6 +169,18 @@ public abstract class AbstractGuiDropdownMenu<V, T extends AbstractGuiDropdownMe
         return opened ? Collections.<GuiElement>singletonList(dropdown) : Collections.<GuiElement>emptyList();
     }
 
+    @Override
+    public T onSelection(Consumer<Integer> consumer) {
+        this.onSelection = consumer;
+        return getThis();
+    }
+
+    public void onSelection(Integer value) {
+        if (onSelection != null) {
+            onSelection.consume(value);
+        }
+    }
+
     @Override
     public boolean mouseClick(ReadablePoint position, int button) {
         Point pos = new Point(position);

src/main/java/de/johni0702/minecraft/gui/element/advanced/IGuiDropdownMenu.java

@@ -23,6 +23,7 @@
 package de.johni0702.minecraft.gui.element.advanced;
 
 import de.johni0702.minecraft.gui.element.GuiElement;
+import de.johni0702.minecraft.gui.utils.Consumer;
 
 public interface IGuiDropdownMenu<V, T extends IGuiDropdownMenu<V, T>> extends GuiElement<T> {
     T setValues(V... values);
@@ -40,4 +41,6 @@ public interface IGuiDropdownMenu<V, T extends IGuiDropdownMenu<V, T>> extends G
     V[] getValues();
 
     boolean isOpened();
+
+    T onSelection(Consumer<Integer> consumer);
 }