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.g2d.NinePatch; import com.badlogic.gdx.graphics.g2d.TextureRegion; 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.Drawable; import com.badlogic.gdx.utils.Pools; /** A slider is a horizontal indicator that allows a user to set a value. The slider has a range (min, max) and a stepping between * each value the slider represents. * <p> * {@link ChangeEvent} is fired when the slider knob is moved. Canceling the event will move the knob to where it was previously. * <p> * The preferred height of a slider is determined by the larger of the knob and background. The preferred width of a slider is * 140, a relatively arbitrary size. * @author mzechner * @author Nathan Sweet */ public class Slider extends ProgressBar { int draggingPointer = -1; public Slider(float min, float max, float stepSize, boolean vertical, Skin skin) { this(min, max, stepSize, vertical, skin.get("default-" + (vertical ? "vertical" : "horizontal"), SliderStyle.class)); } public Slider(float min, float max, float stepSize, boolean vertical, Skin skin, String styleName) { this(min, max, stepSize, vertical, skin.get(styleName, SliderStyle.class)); } /** Creates a new slider. It's width is determined by the given prefWidth parameter, its height is determined by the maximum of * the height of either the slider {@link NinePatch} or slider handle {@link TextureRegion}. The min and max values determine * the range the values of this slider can take on, the stepSize parameter specifies the distance between individual values. * E.g. min could be 4, max could be 10 and stepSize could be 0.2, giving you a total of 30 values, 4.0 4.2, 4.4 and so on. * @param min the minimum value * @param max the maximum value * @param stepSize the step size between values * @param style the {@link SliderStyle} */ public Slider(float min, float max, float stepSize, boolean vertical, SliderStyle style) { super(min, max, stepSize, vertical, style); shiftIgnoresSnap = true; addListener(new InputListener() { public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) { if (disabled) return false; if (draggingPointer != -1) return false; draggingPointer = pointer; calculatePositionAndValue(x, y); return true; } public void touchUp(InputEvent event, float x, float y, int pointer, int button) { if (pointer != draggingPointer) return; draggingPointer = -1; if (!calculatePositionAndValue(x, y)) { // Fire an event on touchUp even if the value didn't change, so listeners can see when a drag ends via isDragging. ChangeEvent changeEvent = Pools.obtain(ChangeEvent.class); fire(changeEvent); Pools.free(changeEvent); } } public void touchDragged(InputEvent event, float x, float y, int pointer) { calculatePositionAndValue(x, y); } }); } public void setStyle(SliderStyle style) { if (style == null) throw new NullPointerException("style cannot be null"); if (!(style instanceof SliderStyle)) throw new IllegalArgumentException("style must be a SliderStyle."); super.setStyle(style); } /** Returns the slider's style. Modifying the returned style may not have an effect until {@link #setStyle(SliderStyle)} is * called. */ public SliderStyle getStyle() { return (SliderStyle) super.getStyle(); } boolean calculatePositionAndValue(float x, float y) { final SliderStyle style = getStyle(); final Drawable knob = (disabled && style.disabledKnob != null) ? style.disabledKnob : style.knob; final Drawable bg = (disabled && style.disabledBackground != null) ? style.disabledBackground : style.background; float value; float oldPosition = position; final float min = getMinValue(); final float max = getMaxValue(); if (vertical) { float height = getHeight() - bg.getTopHeight() - bg.getBottomHeight(); float knobHeight = knob == null ? 0 : knob.getMinHeight(); position = y - bg.getBottomHeight() - knobHeight * 0.5f; value = min + (max - min) * (position / (height - knobHeight)); position = Math.max(0, position); position = Math.min(height - knobHeight, position); } else { float width = getWidth() - bg.getLeftWidth() - bg.getRightWidth(); float knobWidth = knob == null ? 0 : knob.getMinWidth(); position = x - bg.getLeftWidth() - knobWidth * 0.5f; value = min + (max - min) * (position / (width - knobWidth)); position = Math.max(0, position); position = Math.min(width - knobWidth, position); } float oldValue = value; boolean valueSet = setValue(value); if (value == oldValue) position = oldPosition; return valueSet; } /** Returns true if the slider is being dragged. */ public boolean isDragging() { return draggingPointer != -1; } /** The style for a slider, see {@link Slider}. * @author mzechner * @author Nathan Sweet */ static public class SliderStyle extends ProgressBarStyle { public SliderStyle() { } public SliderStyle(Drawable background, Drawable knob) { super(background, knob); } public SliderStyle(SliderStyle style) { super(style); } } }