yes!

6 files changed, 173 insertions, 23 deletions

diff --git a/src/main/java/io/github/cottonmc/cotton/gui/client/CottonClientScreen.java b/src/main/java/io/github/cottonmc/cotton/gui/client/CottonClientScreen.java
index cb80707..674fd77 100644
--- a/src/main/java/io/github/cottonmc/cotton/gui/client/CottonClientScreen.java
+++ b/src/main/java/io/github/cottonmc/cotton/gui/client/CottonClientScreen.java
@@ -36,6 +36,8 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 
 	@Nullable
 	protected WWidget lastResponder = null;
+
+	private final MouseInputHandler<CottonClientScreen> mouseInputHandler = new MouseInputHandler<>(this);
 	
 	public CottonClientScreen(GuiDescription description) {
 		this(new LiteralText(""), description);
@@ -46,7 +48,8 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 		this.description = description;
 		description.getRootPanel().validate(description);
 	}
-	
+
+	@Override
 	public GuiDescription getDescription() {
 		return description;
 	}
@@ -176,7 +179,7 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 		int containerX = (int)mouseX-left;
 		int containerY = (int)mouseY-top;
 		if (containerX<0 || containerY<0 || containerX>=width || containerY>=height) return true;
-		MouseInputHandler.onMouseDown(description, this, containerX, containerY, mouseButton);
+		mouseInputHandler.onMouseDown(containerX, containerY, mouseButton);
 
 		return true;
 	}
@@ -187,7 +190,7 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 		super.mouseReleased(mouseX, mouseY, mouseButton);
 		int containerX = (int)mouseX-left;
 		int containerY = (int)mouseY-top;
-		MouseInputHandler.onMouseUp(description, this, containerX, containerY, mouseButton);
+		mouseInputHandler.onMouseUp(containerX, containerY, mouseButton);
 		
 		return true;
 	}
@@ -199,7 +202,7 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 		
 		int containerX = (int)mouseX-left;
 		int containerY = (int)mouseY-top;
-		MouseInputHandler.onMouseDrag(description, this, containerX, containerY, mouseButton, deltaX, deltaY);
+		mouseInputHandler.onMouseDrag(containerX, containerY, mouseButton, deltaX, deltaY);
 
 		return true;
 	}
@@ -210,7 +213,7 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 		
 		int containerX = (int)mouseX-left;
 		int containerY = (int)mouseY-top;
-		MouseInputHandler.onMouseScroll(description, containerX, containerY, amount);
+		mouseInputHandler.onMouseScroll(containerX, containerY, amount);
 
 		return true;
 	}
@@ -221,7 +224,7 @@ public class CottonClientScreen extends Screen implements CottonScreenImpl {
 
 		int containerX = (int)mouseX-left;
 		int containerY = (int)mouseY-top;
-		MouseInputHandler.onMouseMove(description, containerX, containerY);
+		mouseInputHandler.onMouseMove(containerX, containerY);
 	}
 
 	@Override
diff --git a/src/main/java/io/github/cottonmc/cotton/gui/client/CottonInventoryScreen.java b/src/main/java/io/github/cottonmc/cotton/gui/client/CottonInventoryScreen.java
index 87d9453..01a5092 100644
--- a/src/main/java/io/github/cottonmc/cotton/gui/client/CottonInventoryScreen.java
+++ b/src/main/java/io/github/cottonmc/cotton/gui/client/CottonInventoryScreen.java
@@ -8,12 +8,14 @@ import net.minecraft.text.LiteralText;
 import net.minecraft.text.Style;
 import net.minecraft.text.Text;
 
+import io.github.cottonmc.cotton.gui.GuiDescription;
 import io.github.cottonmc.cotton.gui.SyncedGuiDescription;
 import io.github.cottonmc.cotton.gui.impl.VisualLogger;
 import io.github.cottonmc.cotton.gui.impl.client.CottonScreenImpl;
 import io.github.cottonmc.cotton.gui.impl.client.MouseInputHandler;
 import io.github.cottonmc.cotton.gui.widget.WPanel;
 import io.github.cottonmc.cotton.gui.widget.WWidget;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.Nullable;
 import org.lwjgl.glfw.GLFW;
 import org.lwjgl.opengl.GL11;
@@ -26,6 +28,7 @@ import org.lwjgl.opengl.GL11;
 public class CottonInventoryScreen<T extends SyncedGuiDescription> extends HandledScreen<T> implements CottonScreenImpl {
 	protected SyncedGuiDescription description;
 	@Nullable protected WWidget lastResponder = null;
+	private final MouseInputHandler<CottonInventoryScreen<T>> mouseInputHandler = new MouseInputHandler<>(this);
 
 	/**
 	 * Constructs a new screen without a title.
@@ -83,6 +86,12 @@ public class CottonInventoryScreen<T extends SyncedGuiDescription> extends Handl
 		VisualLogger.reset();
 	}
 
+	@ApiStatus.Internal
+	@Override
+	public GuiDescription getDescription() {
+		return description;
+	}
+
 	@Nullable
 	@Override
 	public WWidget getLastResponder() {
@@ -187,7 +196,7 @@ public class CottonInventoryScreen<T extends SyncedGuiDescription> extends Handl
 		int containerX = (int)mouseX-x;
 		int containerY = (int)mouseY-y;
 		if (containerX<0 || containerY<0 || containerX>=width || containerY>=height) return result;
-		MouseInputHandler.onMouseDown(description, this, containerX, containerY, mouseButton);
+		mouseInputHandler.onMouseDown(containerX, containerY, mouseButton);
 
 		return true;
 	}
@@ -197,7 +206,7 @@ public class CottonInventoryScreen<T extends SyncedGuiDescription> extends Handl
 		super.mouseReleased(mouseX, mouseY, mouseButton);
 		int containerX = (int)mouseX-x;
 		int containerY = (int)mouseY-y;
-		MouseInputHandler.onMouseUp(description, this, containerX, containerY, mouseButton);
+		mouseInputHandler.onMouseUp(containerX, containerY, mouseButton);
 
 		return true;
 	}
@@ -208,7 +217,7 @@ public class CottonInventoryScreen<T extends SyncedGuiDescription> extends Handl
 		
 		int containerX = (int)mouseX-x;
 		int containerY = (int)mouseY-y;
-		MouseInputHandler.onMouseDrag(description, this, containerX, containerY, mouseButton, deltaX, deltaY);
+		mouseInputHandler.onMouseDrag(containerX, containerY, mouseButton, deltaX, deltaY);
 
 		return true;
 	}
@@ -219,7 +228,7 @@ public class CottonInventoryScreen<T extends SyncedGuiDescription> extends Handl
 
 		int containerX = (int)mouseX-x;
 		int containerY = (int)mouseY-y;
-		MouseInputHandler.onMouseScroll(description, containerX, containerY, amount);
+		mouseInputHandler.onMouseScroll(containerX, containerY, amount);
 
 		return true;
 	}
@@ -230,7 +239,7 @@ public class CottonInventoryScreen<T extends SyncedGuiDescription> extends Handl
 
 		int containerX = (int)mouseX-x;
 		int containerY = (int)mouseY-y;
-		MouseInputHandler.onMouseMove(description, containerX, containerY);
+		mouseInputHandler.onMouseMove(containerX, containerY);
 	}
 
 	@Override
diff --git a/src/main/java/io/github/cottonmc/cotton/gui/impl/client/CottonScreenImpl.java b/src/main/java/io/github/cottonmc/cotton/gui/impl/client/CottonScreenImpl.java
index 2ef9632..cd215b3 100644
--- a/src/main/java/io/github/cottonmc/cotton/gui/impl/client/CottonScreenImpl.java
+++ b/src/main/java/io/github/cottonmc/cotton/gui/impl/client/CottonScreenImpl.java
@@ -5,11 +5,14 @@ import net.fabricmc.api.Environment;
 import net.minecraft.client.util.math.MatrixStack;
 import net.minecraft.text.Style;
 
+import io.github.cottonmc.cotton.gui.GuiDescription;
 import io.github.cottonmc.cotton.gui.widget.WWidget;
 import org.jetbrains.annotations.Nullable;
 
 @Environment(EnvType.CLIENT)
 public interface CottonScreenImpl {
+	GuiDescription getDescription();
+
 	@Nullable
 	WWidget getLastResponder();
 
diff --git a/src/main/java/io/github/cottonmc/cotton/gui/impl/client/MouseInputHandler.java b/src/main/java/io/github/cottonmc/cotton/gui/impl/client/MouseInputHandler.java
index 45fc17f..4791c39 100644
--- a/src/main/java/io/github/cottonmc/cotton/gui/impl/client/MouseInputHandler.java
+++ b/src/main/java/io/github/cottonmc/cotton/gui/impl/client/MouseInputHandler.java
@@ -2,7 +2,6 @@ package io.github.cottonmc.cotton.gui.impl.client;
 
 import net.minecraft.client.gui.screen.Screen;
 
-import io.github.cottonmc.cotton.gui.GuiDescription;
 import io.github.cottonmc.cotton.gui.widget.WWidget;
 import io.github.cottonmc.cotton.gui.widget.data.InputResult;
 import org.jetbrains.annotations.Nullable;
@@ -12,10 +11,17 @@ import java.util.function.Function;
 /**
  * The implementation for mouse inputs.
  */
-public final class MouseInputHandler {
-	public static void onMouseDown(GuiDescription description, CottonScreenImpl screen, int containerX, int containerY, int mouseButton) {
+public final class MouseInputHandler<S extends Screen & CottonScreenImpl> {
+	private final S screen;
+	private @Nullable WWidget hovered;
+
+	public MouseInputHandler(S screen) {
+		this.screen = screen;
+	}
+
+	public void onMouseDown(int containerX, int containerY, int mouseButton) {
 		if (screen.getLastResponder() == null) {
-			WWidget lastResponder = description.getRootPanel().hit(containerX, containerY);
+			WWidget lastResponder = screen.getDescription().getRootPanel().hit(containerX, containerY);
 			screen.setLastResponder(lastResponder);
 			if (lastResponder != null) {
 				runTree(
@@ -28,7 +34,7 @@ public final class MouseInputHandler {
 		}
 	}
 
-	public static <S extends Screen & CottonScreenImpl> void onMouseUp(GuiDescription description, S screen, int containerX, int containerY, int mouseButton) {
+	public void onMouseUp(int containerX, int containerY, int mouseButton) {
 		WWidget lastResponder = screen.getLastResponder();
 
 		if (lastResponder != null) {
@@ -48,7 +54,7 @@ public final class MouseInputHandler {
 			}
 		} else {
 			runTree(
-					description.getRootPanel().hit(containerX, containerY),
+					screen.getDescription().getRootPanel().hit(containerX, containerY),
 					widget -> widget.onMouseUp(containerX - widget.getAbsoluteX(), containerY - widget.getAbsoluteY(), mouseButton)
 			);
 		}
@@ -56,7 +62,7 @@ public final class MouseInputHandler {
 		screen.setLastResponder(null);
 	}
 
-	public static <S extends Screen & CottonScreenImpl> void onMouseDrag(GuiDescription description, S screen, int containerX, int containerY, int mouseButton, double deltaX, double deltaY) {
+	public void onMouseDrag(int containerX, int containerY, int mouseButton, double deltaX, double deltaY) {
 		WWidget lastResponder = screen.getLastResponder();
 
 		if (lastResponder != null) {
@@ -68,22 +74,34 @@ public final class MouseInputHandler {
 			if (containerX < 0 || containerY < 0 || containerX >= width || containerY >= height) return;
 
 			runTree(
-					description.getRootPanel().hit(containerX, containerY),
+					screen.getDescription().getRootPanel().hit(containerX, containerY),
 					widget -> widget.onMouseDrag(containerX - widget.getAbsoluteX(), containerY - widget.getAbsoluteY(), mouseButton, deltaX, deltaY)
 			);
 		}
 	}
 
-	public static void onMouseScroll(GuiDescription description, int containerX, int containerY, double amount) {
+	public void onMouseScroll(int containerX, int containerY, double amount) {
 		runTree(
-				description.getRootPanel().hit(containerX, containerY),
+				screen.getDescription().getRootPanel().hit(containerX, containerY),
 				widget -> widget.onMouseScroll(containerX - widget.getAbsoluteX(), containerY - widget.getAbsoluteY(), amount)
 		);
 	}
 
-	public static void onMouseMove(GuiDescription description, int containerX, int containerY) {
+	public void onMouseMove(int containerX, int containerY) {
+		WWidget hit = screen.getDescription().getRootPanel().hit(containerX, containerY);
+
+		// TODO: Some sort of canHover?
+		if (hit != hovered) {
+			if (hovered != null) {
+				hovered.getHovered().set(false);
+			}
+
+			hovered = hit;
+			hit.getHovered().set(true);
+		}
+
 		runTree(
-				description.getRootPanel().hit(containerX, containerY),
+				hit,
 				widget -> widget.onMouseMove(containerX - widget.getAbsoluteX(), containerY - widget.getAbsoluteY())
 		);
 	}
diff --git a/src/main/java/io/github/cottonmc/cotton/gui/widget/WWidget.java b/src/main/java/io/github/cottonmc/cotton/gui/widget/WWidget.java
index 2a6ae5e..30e14d5 100644
--- a/src/main/java/io/github/cottonmc/cotton/gui/widget/WWidget.java
+++ b/src/main/java/io/github/cottonmc/cotton/gui/widget/WWidget.java
@@ -1,5 +1,7 @@
 package io.github.cottonmc.cotton.gui.widget;
 
+import io.github.cottonmc.cotton.gui.widget.data.ObservableProperty;
+
 import net.fabricmc.api.EnvType;
 import net.fabricmc.api.Environment;
 import net.minecraft.client.MinecraftClient;
@@ -41,6 +43,8 @@ public class WWidget {
 	@Nullable
 	protected GuiDescription host;
 
+	private final ObservableProperty<Boolean> hovered = ObservableProperty.of(false).nonnullValues();
+
 	/**
 	 * Sets the location of this widget relative to its parent.
 	 *
@@ -456,6 +460,10 @@ public class WWidget {
 	public void addPainters() {
 	}
 
+	public ObservableProperty<Boolean> getHovered() {
+		return hovered;
+	}
+
 	/**
 	 * Tests if the provided key code is an activation key for widgets.
 	 *
diff --git a/src/main/java/io/github/cottonmc/cotton/gui/widget/data/ObservableProperty.java b/src/main/java/io/github/cottonmc/cotton/gui/widget/data/ObservableProperty.java
new file mode 100644
index 0000000..723cf60
--- /dev/null
+++ b/src/main/java/io/github/cottonmc/cotton/gui/widget/data/ObservableProperty.java
@@ -0,0 +1,109 @@
+package io.github.cottonmc.cotton.gui.widget.data;
+
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.function.Supplier;
+
+public final class ObservableProperty<T> {
+	private Supplier<? extends T> value;
+	private final List<ChangeListener<? super T>> listeners = new ArrayList<>();
+	private boolean allowNull = true;
+
+	private ObservableProperty() {
+	}
+
+	private ObservableProperty(Supplier<? extends T> value) {
+		this.value = value;
+	}
+
+	public static <T> ObservableProperty<T> lateinit() {
+		return new ObservableProperty<>();
+	}
+
+	public static <T> ObservableProperty<T> of(T initialValue) {
+		return new ObservableProperty<>(() -> initialValue);
+	}
+
+	public static <T> ObservableProperty<T> bound(Supplier<? extends T> initialValue) {
+		return new ObservableProperty<>(initialValue);
+	}
+
+	/**
+	 * {@return the value of this property}
+	 * @throws IllegalStateException if not initialized
+	 * @throws NullPointerException if the value is null and null values aren't allowed
+	 */
+	public T get() {
+		if (value == null) {
+			throw new IllegalStateException("Property not initialized!");
+		}
+
+		T ret = value.get();
+		if (ret == null && !allowNull) throw new NullPointerException("Null value for nonnull property!");
+		return ret;
+	}
+
+	/**
+	 * Sets this property to a constant value.
+	 *
+	 * @param value the new value
+	 * @throws NullPointerException if the value is null and nulls aren't allowed
+	 */
+	public void set(T value) {
+		if (value == null && !allowNull) throw new NullPointerException("value");
+		bind(() -> value);
+	}
+
+	/**
+	 * Binds this property to a supplier.
+	 *
+	 * @param value the new value supplier
+	 */
+	public void bind(Supplier<? extends T> value) {
+		Objects.requireNonNull(value, "value");
+		T oldValue = this.value != null ? this.value.get() : null;
+		this.value = value;
+
+		for (ChangeListener<? super T> listener : listeners) {
+			listener.onPropertyChange(this, oldValue, value.get());
+		}
+	}
+
+	/**
+	 * Clears the current value, if any, from this property.
+	 */
+	public void clear() {
+		T oldValue = this.value != null ? this.value.get() : null;
+		value = null;
+
+		for (ChangeListener<? super T> listener : listeners) {
+			listener.onPropertyChange(this, oldValue, null);
+		}
+	}
+
+	/**
+	 * Prevents this property from accepting null values.
+	 *
+	 * @return this property
+	 */
+	public ObservableProperty<T> nonnullValues() {
+		allowNull = false;
+		return this;
+	}
+
+	public void addListener(ChangeListener<? super T> listener) {
+		listeners.add(listener);
+	}
+
+	public void removeListener(ChangeListener<? super T> listener) {
+		listeners.remove(listener);
+	}
+
+	@FunctionalInterface
+	public interface ChangeListener<T> {
+		void onPropertyChange(ObservableProperty<? extends T> property, @Nullable T from, @Nullable T to);
+	}
+}