Java tutorial
/******************************************************************************* * 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.Batch; import com.badlogic.gdx.graphics.g2d.BitmapFont; import com.badlogic.gdx.graphics.g2d.BitmapFont.TextBounds; 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.ArraySelection; 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.Array; import com.badlogic.gdx.utils.ObjectSet; /** 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 * @author Nathan Sweet */ public class List<T> extends Widget implements Cullable { private ListStyle style; private final Array<T> items = new Array(); final ArraySelection<T> selection = new ArraySelection(items); private Rectangle cullingArea; private float prefWidth, prefHeight; private float itemHeight; private float textOffsetX, textOffsetY; public List(Skin skin) { this(skin.get(ListStyle.class)); } public List(Skin skin, String styleName) { this(skin.get(styleName, ListStyle.class)); } public List(ListStyle style) { selection.setActor(this); selection.setRequired(true); setStyle(style); setSize(getPrefWidth(), getPrefHeight()); addListener(new InputListener() { public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) { if (pointer == 0 && button != 0) return false; if (selection.isDisabled()) return false; List.this.touchDown(y); return true; } }); } void touchDown(float y) { if (items.size == 0) return; float height = getHeight(); if (style.background != null) { height -= style.background.getTopHeight() + style.background.getBottomHeight(); y -= style.background.getBottomHeight(); } int index = (int) ((height - y) / itemHeight); index = Math.max(0, index); index = Math.min(items.size - 1, index); selection.choose(items.get(index)); } public void setStyle(ListStyle style) { if (style == null) throw new IllegalArgumentException("style cannot be null."); this.style = style; 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; } public void layout() { 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.size; i++) { TextBounds bounds = font.getBounds(items.get(i).toString()); prefWidth = Math.max(bounds.width, prefWidth); } prefWidth += selectedDrawable.getLeftWidth() + selectedDrawable.getRightWidth(); prefHeight = items.size * itemHeight; Drawable background = style.background; if (background != null) { prefWidth += background.getLeftWidth() + background.getRightWidth(); prefHeight += background.getTopHeight() + background.getBottomHeight(); } } @Override public void draw(Batch batch, float parentAlpha) { validate(); 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(), y = getY(), width = getWidth(), height = getHeight(); float itemY = height; Drawable background = style.background; if (background != null) { background.draw(batch, x, y, width, height); float leftWidth = background.getLeftWidth(); x += leftWidth; itemY -= background.getTopHeight(); width -= leftWidth + background.getRightWidth(); } font.setColor(fontColorUnselected.r, fontColorUnselected.g, fontColorUnselected.b, fontColorUnselected.a * parentAlpha); for (int i = 0; i < items.size; i++) { if (cullingArea == null || (itemY - itemHeight <= cullingArea.y + cullingArea.height && itemY >= cullingArea.y)) { T item = items.get(i); boolean selected = selection.contains(item); if (selected) { selectedDrawable.draw(batch, x, y + itemY - itemHeight, width, itemHeight); font.setColor(fontColorSelected.r, fontColorSelected.g, fontColorSelected.b, fontColorSelected.a * parentAlpha); } font.draw(batch, item.toString(), x + textOffsetX, y + itemY - textOffsetY); if (selected) { font.setColor(fontColorUnselected.r, fontColorUnselected.g, fontColorUnselected.b, fontColorUnselected.a * parentAlpha); } } else if (itemY < cullingArea.y) { break; } itemY -= itemHeight; } } public ArraySelection<T> getSelection() { return selection; } /** Returns the first selected item, or null. */ public T getSelected() { return selection.first(); } /** Sets the selection to only the passed item, if it is a possible choice. */ public void setSelected(T item) { if (items.contains(item, false)) selection.set(item); else if (selection.getRequired() && items.size > 0) selection.set(items.first()); else selection.clear(); } /** @return The index of the first selected item. The top item has an index of 0. Nothing selected has an index of -1. */ public int getSelectedIndex() { ObjectSet<T> selected = selection.items(); return selected.size == 0 ? -1 : items.indexOf(selected.first(), false); } /** Sets the selection to only the selected index. */ public void setSelectedIndex(int index) { if (index < -1 || index >= items.size) throw new IllegalArgumentException("index must be >= -1 and < " + items.size + ": " + index); if (index == -1) { selection.clear(); } else { selection.set(items.get(index)); } } public void setItems(T... newItems) { if (newItems == null) throw new IllegalArgumentException("newItems cannot be null."); float oldPrefWidth = getPrefWidth(), oldPrefHeight = getPrefHeight(); items.clear(); items.addAll(newItems); selection.validate(); invalidate(); if (oldPrefWidth != getPrefWidth() || oldPrefHeight != getPrefHeight()) invalidateHierarchy(); } /** Sets the current items, clearing the selection if it is no longer valid. If a selection is * {@link ArraySelection#getRequired()}, the first item is selected. */ public void setItems(Array newItems) { if (newItems == null) throw new IllegalArgumentException("newItems cannot be null."); float oldPrefWidth = getPrefWidth(), oldPrefHeight = getPrefHeight(); items.clear(); items.addAll(newItems); selection.validate(); invalidate(); if (oldPrefWidth != getPrefWidth() || oldPrefHeight != getPrefHeight()) invalidateHierarchy(); } public void clearItems() { if (items.size == 0) return; items.clear(); selection.clear(); invalidateHierarchy(); } public Array<T> getItems() { return items; } public float getItemHeight() { return itemHeight; } public float getPrefWidth() { validate(); return prefWidth; } public float getPrefHeight() { validate(); 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; /** Optional. */ public Drawable background; 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; } } }