Create VScrollable container

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/base/GUI.java

@@ -113,4 +113,6 @@ public interface GUI extends Renderable, Disposable, KeyEventHandler {
    void imagePattern(float x, float y, float width, float height, float angle, float alpha, Image image, Paint target);
 
    void clip(float x, float y, float width, float height);
+
+   void resetClip();
 }

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/component/BaseContainer.java

@@ -8,6 +8,7 @@ import java.util.LinkedList;
 import java.util.List;
 
 import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNull;
 
 public abstract class BaseContainer extends BaseComponent implements Container {
    protected final List<Component> children = new LinkedList<>();
@@ -24,13 +25,13 @@ public abstract class BaseContainer extends BaseComponent implements Container {
 
    @Override
    public void add(Component component) {
-      this.children.add(component);
+      this.children.add(requireNonNull(component));
       component.setParent(this);
    }
 
    @Override
    public void remove(Component component) {
-      this.children.remove(component);
+      this.children.remove(requireNonNull(component));
       component.setParent(null);
    }
 

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/component/SingleChildContainer.java

@@ -0,0 +1,25 @@
+package com.bartlomiejpluta.base.api.game.gui.component;
+
+import com.bartlomiejpluta.base.api.game.context.Context;
+import com.bartlomiejpluta.base.api.game.gui.base.GUI;
+
+public abstract class SingleChildContainer extends BaseContainer {
+   protected Component child;
+
+   protected SingleChildContainer(Context context, GUI gui) {
+      super(context, gui);
+   }
+
+   @Override
+   public void add(Component component) {
+      children.clear();
+      super.add(component);
+      this.child = component;
+   }
+
+   @Override
+   public void remove(Component component) {
+      super.remove(component);
+      this.child = null;
+   }
+}

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/component/VScrollable.java

@@ -0,0 +1,125 @@
+package com.bartlomiejpluta.base.api.game.gui.component;
+
+import com.bartlomiejpluta.base.api.game.context.Context;
+import com.bartlomiejpluta.base.api.game.gui.base.GUI;
+import com.bartlomiejpluta.base.api.game.gui.base.SizeMode;
+import com.bartlomiejpluta.base.api.game.input.Key;
+import com.bartlomiejpluta.base.api.game.input.KeyAction;
+import com.bartlomiejpluta.base.api.game.input.KeyEvent;
+import com.bartlomiejpluta.base.api.game.screen.Screen;
+
+import static com.bartlomiejpluta.base.api.util.math.MathUtil.clamp;
+import static java.lang.Math.*;
+
+public class VScrollable extends SingleChildContainer {
+   private float scroll = 0.0f;
+   private float scrollStep = 0.25f;
+   private float scrollSpeed = 0.1f;
+
+   private float scrollTarget = 0.0f;
+   private float scrollPosition = 0.0f;
+
+   public VScrollable(Context context, GUI gui) {
+      super(context, gui);
+   }
+
+   public float getScroll() {
+      return scroll;
+   }
+
+   public void setScroll(Float scroll) {
+      this.scroll = clamp(scroll, 0, 1);
+   }
+
+   public float getScrollStep() {
+      return scrollStep;
+   }
+
+   public void setScrollStep(Float scrollStep) {
+      this.scrollStep = clamp(scrollStep, 0, 1);
+   }
+
+   public float getScrollSpeed() {
+      return scrollSpeed;
+   }
+
+   public void setScrollSpeed(Float scrollSpeed) {
+      this.scrollSpeed = clamp(scrollSpeed, 0, 1);
+   }
+
+   @Override
+   public void remove(Component component) {
+      throw new UnsupportedOperationException();
+   }
+
+   @Override
+   public void setSizeMode(SizeMode widthMode, SizeMode heightMode) {
+      if (widthMode == SizeMode.AUTO || heightMode == SizeMode.AUTO) {
+         throw new IllegalStateException("Scrollable component size mode must be other than AUTO");
+      }
+
+      super.setSizeMode(widthMode, heightMode);
+   }
+
+   @Override
+   public void setWidthMode(SizeMode mode) {
+      if (mode == SizeMode.AUTO) {
+         throw new IllegalStateException("Scrollable component size mode must be other than AUTO");
+      }
+
+      super.setWidthMode(mode);
+   }
+
+   @Override
+   public void setHeightMode(SizeMode mode) {
+      if (mode == SizeMode.AUTO) {
+         throw new IllegalStateException("Scrollable component size mode must be other than AUTO");
+      }
+
+      super.setHeightMode(mode);
+   }
+
+   @Override
+   protected float getContentWidth() {
+      return child.getMarginLeft() + child.getActualWidth() + child.getMarginRight();
+   }
+
+   @Override
+   protected float getContentHeight() {
+      return child.getMarginTop() + child.getActualHeight() + child.getMarginBottom();
+   }
+
+   @Override
+   public void handleKeyEvent(KeyEvent event) {
+      super.handleKeyEvent(event);
+
+      if (event.isConsumed()) {
+         return;
+      }
+
+      if (event.getKey() == Key.KEY_DOWN && (event.getAction() == KeyAction.PRESS || event.getAction() == KeyAction.REPEAT)) {
+         scroll = min(scroll + scrollStep, 1);
+         scrollTarget = scroll * max(getContentHeight() - getHeight(), 0);
+         event.consume();
+      }
+
+      if (event.getKey() == Key.KEY_UP && (event.getAction() == KeyAction.PRESS || event.getAction() == KeyAction.REPEAT)) {
+         scroll = max(scroll - scrollStep, 0);
+         scrollTarget = scroll * max(getContentHeight() - getHeight(), 0);
+         event.consume();
+      }
+   }
+
+   @Override
+   public void draw(Screen screen, GUI gui) {
+      var remainingDistance = scrollTarget - scrollPosition;
+      if (abs(remainingDistance) > scrollSpeed) {
+         scrollPosition += scrollSpeed * remainingDistance;
+      }
+
+      gui.clip(x, y, getWidth(), getHeight());
+      child.setPosition(x + paddingLeft + child.getMarginLeft(), y + paddingTop + child.getMarginTop() - scrollPosition);
+      child.draw(screen, gui);
+      gui.resetClip();
+   }
+}

api/src/main/java/com/bartlomiejpluta/base/api/util/math/MathUtil.java

@@ -0,0 +1,32 @@
+package com.bartlomiejpluta.base.api.util.math;
+
+import static java.lang.Math.max;
+import static java.lang.Math.min;
+
+public class MathUtil {
+   public static int gcdEuclidean(int a, int b) {
+      int x = a;
+      int y = b;
+      int z;
+
+      while(y != 0) {
+         z = x % y;
+         x = y;
+         y = z;
+      }
+
+      return x;
+   }
+
+   public static int clamp(int value, int min, int max) {
+      return min(max, max(value, min));
+   }
+
+   public static float clamp(float value, float min, float max) {
+      return min(max, max(value, min));
+   }
+
+   public static double clamp(double value, double min, double max) {
+      return min(max, max(value, min));
+   }
+}