/gdx/src/com/badlogic/gdx/scenes/scene2d/ui/List.java

/*******************************************************************************

 * Copyright 2011 See AUTHORS file.

 * 

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 * 

 *   http://www.apache.org/licenses/LICENSE-2.0

 * 

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 ******************************************************************************/



package com.badlogic.gdx.scenes.scene2d.ui;



import com.badlogic.gdx.graphics.Color;

import com.badlogic.gdx.graphics.g2d.BitmapFont;

import com.badlogic.gdx.graphics.g2d.BitmapFont.TextBounds;

import com.badlogic.gdx.graphics.g2d.SpriteBatch;

import com.badlogic.gdx.math.Rectangle;

import com.badlogic.gdx.scenes.scene2d.InputEvent;

import com.badlogic.gdx.scenes.scene2d.InputListener;

import com.badlogic.gdx.scenes.scene2d.utils.ChangeListener.ChangeEvent;

import com.badlogic.gdx.scenes.scene2d.utils.Cullable;

import com.badlogic.gdx.scenes.scene2d.utils.Drawable;

import com.badlogic.gdx.utils.GdxRuntimeException;

import com.badlogic.gdx.utils.Pools;



/** A list (aka list box) displays textual items and highlights the currently selected item.

 * <p>

 * {@link ChangeEvent} is fired when the list selection changes.

 * <p>

 * The preferred size of the list is determined by the text bounds of the items and the size of the {@link ListStyle#selection}.

 * @author mzechner */

public class List extends Widget implements Cullable {

	private ListStyle style;

	private String[] items;

	private int selectedIndex;

	private Rectangle cullingArea;

	private float prefWidth, prefHeight;

	private float itemHeight;

	private float textOffsetX, textOffsetY;



	public List (Object[] items, Skin skin) {

		this(items, skin.get(ListStyle.class));

	}



	public List (Object[] items, Skin skin, String styleName) {

		this(items, skin.get(styleName, ListStyle.class));

	}



	public List (Object[] items, ListStyle style) {

		setStyle(style);

		setItems(items);

		setWidth(getPrefWidth());

		setHeight(getPrefHeight());



		addListener(new InputListener() {

			public boolean touchDown (InputEvent event, float x, float y, int pointer, int button) {

				if (pointer == 0 && button != 0) return false;

				List.this.touchDown(y);

				return true;

			}

		});

	}



	void touchDown (float y) {

		int oldIndex = selectedIndex;

		selectedIndex = (int)((getHeight() - y) / itemHeight);

		selectedIndex = Math.max(0, selectedIndex);

		selectedIndex = Math.min(items.length - 1, selectedIndex);

		if (oldIndex != selectedIndex) {

			ChangeEvent changeEvent = Pools.obtain(ChangeEvent.class);

			if (fire(changeEvent)) selectedIndex = oldIndex;

			Pools.free(changeEvent);

		}

	}



	public void setStyle (ListStyle style) {

		if (style == null) throw new IllegalArgumentException("style cannot be null.");

		this.style = style;

		if (items != null)

			setItems(items);

		else

			invalidateHierarchy();

	}



	/** Returns the list's style. Modifying the returned style may not have an effect until {@link #setStyle(ListStyle)} is called. */

	public ListStyle getStyle () {

		return style;

	}



	@Override

	public void draw (SpriteBatch batch, float parentAlpha) {

		BitmapFont font = style.font;

		Drawable selectedDrawable = style.selection;

		Color fontColorSelected = style.fontColorSelected;

		Color fontColorUnselected = style.fontColorUnselected;



		Color color = getColor();

		batch.setColor(color.r, color.g, color.b, color.a * parentAlpha);



		float x = getX();

		float y = getY();



		font.setColor(fontColorUnselected.r, fontColorUnselected.g, fontColorUnselected.b, fontColorUnselected.a * parentAlpha);

		float itemY = getHeight();

		for (int i = 0; i < items.length; i++) {

			if (cullingArea == null || (itemY - itemHeight <= cullingArea.y + cullingArea.height && itemY >= cullingArea.y)) {

				if (selectedIndex == i) {

					selectedDrawable.draw(batch, x, y + itemY - itemHeight, prefWidth, itemHeight);

					font.setColor(fontColorSelected.r, fontColorSelected.g, fontColorSelected.b, fontColorSelected.a * parentAlpha);

				}

				font.draw(batch, items[i], x + textOffsetX, y + itemY - textOffsetY);

				if (selectedIndex == i) {

					font.setColor(fontColorUnselected.r, fontColorUnselected.g, fontColorUnselected.b, fontColorUnselected.a

						* parentAlpha);

				}

			} else if (itemY < cullingArea.y) {

				break;

			}

			itemY -= itemHeight;

		}

	}



	/** @return The index of the currently selected item. The top item has an index of 0. */

	public int getSelectedIndex () {

		return selectedIndex;

	}



	public void setSelectedIndex (int index) {

		if (index < 0 || index >= items.length)

			throw new GdxRuntimeException("index must be >= 0 and < " + items.length + ": " + index);

		selectedIndex = index;

	}



	/** @return The text of the currently selected item or null if the list is empty. */

	public String getSelection () {

		if (items.length == 0) return null;

		return items[selectedIndex];

	}



	/** @return The index of the item that was selected, or -1. */

	public int setSelection (String item) {

		selectedIndex = -1;

		for (int i = 0, n = items.length; i < n; i++) {

			if (items[i].equals(item)) {

				selectedIndex = i;

				break;

			}

		}

		return selectedIndex;

	}



	public void setItems (Object[] objects) {

		if (objects == null) throw new IllegalArgumentException("items cannot be null.");



		if (!(objects instanceof String[])) {

			String[] strings = new String[objects.length];

			for (int i = 0, n = objects.length; i < n; i++)

				strings[i] = String.valueOf(objects[i]);

			items = strings;

		} else

			items = (String[])objects;



		selectedIndex = 0;



		final BitmapFont font = style.font;

		final Drawable selectedDrawable = style.selection;



		itemHeight = font.getCapHeight() - font.getDescent() * 2;

		itemHeight += selectedDrawable.getTopHeight() + selectedDrawable.getBottomHeight();

		textOffsetX = selectedDrawable.getLeftWidth();

		textOffsetY = selectedDrawable.getTopHeight() - font.getDescent();



		prefWidth = 0;

		for (int i = 0; i < items.length; i++) {

			TextBounds bounds = font.getBounds(items[i]);

			prefWidth = Math.max(bounds.width, prefWidth);

		}

		prefWidth += selectedDrawable.getLeftWidth() + selectedDrawable.getRightWidth();

		prefHeight = items.length * itemHeight;



		invalidateHierarchy();

	}



	public String[] getItems () {

		return items;

	}



	public float getPrefWidth () {

		return prefWidth;

	}



	public float getPrefHeight () {

		return prefHeight;

	}



	public void setCullingArea (Rectangle cullingArea) {

		this.cullingArea = cullingArea;

	}



	/** The style for a list, see {@link List}.

	 * @author mzechner

	 * @author Nathan Sweet */

	static public class ListStyle {

		public BitmapFont font;

		public Color fontColorSelected = new Color(1, 1, 1, 1);

		public Color fontColorUnselected = new Color(1, 1, 1, 1);

		public Drawable selection;



		public ListStyle () {

		}



		public ListStyle (BitmapFont font, Color fontColorSelected, Color fontColorUnselected, Drawable selection) {

			this.font = font;

			this.fontColorSelected.set(fontColorSelected);

			this.fontColorUnselected.set(fontColorUnselected);

			this.selection = selection;

		}



		public ListStyle (ListStyle style) {

			this.font = style.font;

			this.fontColorSelected.set(style.fontColorSelected);

			this.fontColorUnselected.set(style.fontColorUnselected);

			this.selection = style.selection;

		}

	}

}