com.badlogic.gdx.scenes.scene2d.ui.WidgetGroup.java Source code

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Here is the source code for com.badlogic.gdx.scenes.scene2d.ui.WidgetGroup.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.ui;

import com.badlogic.gdx.graphics.g2d.Batch;
import com.badlogic.gdx.scenes.scene2d.Actor;
import com.badlogic.gdx.scenes.scene2d.Group;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.Touchable;
import com.badlogic.gdx.scenes.scene2d.utils.Layout;
import com.badlogic.gdx.utils.SnapshotArray;

/** A {@link Group} that participates in layout and provides a minimum, preferred, and maximum size.
 * <p>
 * The default preferred size of a widget group is 0 and this is almost always overridden by a subclass. The default minimum size
 * returns the preferred size, so a subclass may choose to return 0 for minimum size if it wants to allow itself to be sized
 * smaller than the preferred size. The default maximum size is 0, which means no maximum size.
 * <p>
 * See {@link Layout} for details on how a widget group should participate in layout. A widget group's mutator methods should call
 * {@link #invalidate()} or {@link #invalidateHierarchy()} as needed. By default, invalidateHierarchy is called when child widgets
 * are added and removed.
 * @author Nathan Sweet */
public class WidgetGroup extends Group implements Layout {
    private boolean needsLayout = true;
    private boolean fillParent;
    private boolean layoutEnabled = true;

    public float getMinWidth() {
        return getPrefWidth();
    }

    public float getMinHeight() {
        return getPrefHeight();
    }

    public float getPrefWidth() {
        return 0;
    }

    public float getPrefHeight() {
        return 0;
    }

    public float getMaxWidth() {
        return 0;
    }

    public float getMaxHeight() {
        return 0;
    }

    public void setLayoutEnabled(boolean enabled) {
        if (layoutEnabled == enabled)
            return;
        layoutEnabled = enabled;
        setLayoutEnabled(this, enabled);
    }

    private void setLayoutEnabled(Group parent, boolean enabled) {
        SnapshotArray<Actor> children = parent.getChildren();
        for (int i = 0, n = children.size; i < n; i++) {
            Actor actor = children.get(i);
            if (actor instanceof Layout)
                ((Layout) actor).setLayoutEnabled(enabled);
            else if (actor instanceof Group) //
                setLayoutEnabled((Group) actor, enabled);
        }
    }

    public void validate() {
        if (!layoutEnabled)
            return;
        Group parent = getParent();
        if (fillParent && parent != null) {
            Stage stage = getStage();

            float parentWidth, parentHeight;
            if (stage != null && parent == stage.getRoot()) {
                parentWidth = stage.getWidth();
                parentHeight = stage.getHeight();
            } else {
                parentWidth = parent.getWidth();
                parentHeight = parent.getHeight();
            }
            if (getWidth() != parentWidth || getHeight() != parentHeight) {
                setWidth(parentWidth);
                setHeight(parentHeight);
                invalidate();
            }
        }

        if (!needsLayout)
            return;
        needsLayout = false;
        layout();
    }

    /** Returns true if the widget's layout has been {@link #invalidate() invalidated}. */
    public boolean needsLayout() {
        return needsLayout;
    }

    public void invalidate() {
        needsLayout = true;
    }

    public void invalidateHierarchy() {
        invalidate();
        Group parent = getParent();
        if (parent instanceof Layout)
            ((Layout) parent).invalidateHierarchy();
    }

    protected void childrenChanged() {
        invalidateHierarchy();
    }

    protected void sizeChanged() {
        invalidate();
    }

    public void pack() {
        setSize(getPrefWidth(), getPrefHeight());
        validate();
        // Some situations require another layout. Eg, a wrapped label doesn't know its pref height until it knows its width, so it
        // calls invalidateHierarchy() in layout() if its pref height has changed.
        if (needsLayout) {
            setSize(getPrefWidth(), getPrefHeight());
            validate();
        }
    }

    public void setFillParent(boolean fillParent) {
        this.fillParent = fillParent;
    }

    public void layout() {
    }

    /** If this method is overridden, the super method or {@link #validate()} should be called to ensure the widget group is laid
     * out. */
    public void draw(Batch batch, float parentAlpha) {
        validate();
        super.draw(batch, parentAlpha);
    }
}