com.badlogic.gdx.scenes.scene2d.utils.Layout.java Source code

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Here is the source code for com.badlogic.gdx.scenes.scene2d.utils.Layout.java

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/*******************************************************************************
 * 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.utils;

import com.badlogic.gdx.graphics.g2d.Batch;
import com.badlogic.gdx.scenes.scene2d.Actor;
import com.badlogic.gdx.scenes.scene2d.ui.Table;

/** Provides methods for an actor to participate in layout and to provide a minimum, preferred, and maximum size.
 * @author Nathan Sweet */
public interface Layout {
    /** Computes and caches any information needed for drawing and, if this actor has children, positions and sizes each child,
     * calls {@link #invalidate()} any each child whose width or height has changed, and calls {@link #validate()} on each child.
     * This method should almost never be called directly, instead {@link #validate()} should be used. */
    public void layout();

    /** Invalidates this actor's layout, causing {@link #layout()} to happen the next time {@link #validate()} is called. This
     * method should be called when state changes in the actor that requires a layout but does not change the minimum, preferred,
     * maximum, or actual size of the actor (meaning it does not affect the parent actor's layout). */
    public void invalidate();

    /** Invalidates this actor and all its parents, calling {@link #invalidate()} on each. This method should be called when state
     * changes in the actor that affects the minimum, preferred, maximum, or actual size of the actor (meaning it it potentially
     * affects the parent actor's layout). */
    public void invalidateHierarchy();

    /** Ensures the actor has been laid out. Calls {@link #layout()} if {@link #invalidate()} has been called since the last time
     * {@link #validate()} was called, or if the actor otherwise needs to be laid out. This method is usually called in
     * {@link Actor#draw(Batch, float)} before drawing is performed. */
    public void validate();

    /** Sizes this actor to its preferred width and height, then calls {@link #validate()}.
     * <p>
     * Generally this method should not be called in an actor's constructor because it calls {@link #layout()}, which means a
     * subclass would have layout() called before the subclass' constructor. Instead, in constructors simply set the actor's size
     * to {@link #getPrefWidth()} and {@link #getPrefHeight()}. This allows the actor to have a size at construction time for more
     * convenient use with groups that do not layout their children. */
    public void pack();

    /** If true, this actor will be sized to the parent in {@link #validate()}. If the parent is the stage, the actor will be sized
     * to the stage. This method is for convenience only when the widget's parent does not set the size of its children (such as
     * the stage). */
    public void setFillParent(boolean fillParent);

    /** Enables or disables the layout for this actor and all child actors, recursively. When false, {@link #validate()} will not
     * cause a layout to occur. This can be useful when an actor will be manipulated externally, such as with actions. Default is
     * true. */
    public void setLayoutEnabled(boolean enabled);

    public float getMinWidth();

    public float getMinHeight();

    public float getPrefWidth();

    public float getPrefHeight();

    /** Zero indicates no max width. */
    public float getMaxWidth();

    /** Zero indicates no max height. */
    public float getMaxHeight();
}