AbstractLayer.java

/**
 * Copyright 2010 The ForPlay Authors
 * 
 * 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 forplay.core;

import forplay.core.Layer;

/**
 * Base {@link Layer} implementation shared among platforms (to avoid reinventing the transform
 * logic).
 */
public abstract class AbstractLayer implements Layer {

  protected static enum Flag {
    DESTROYED(1 << 0),
    VISIBLE(1 << 1),
    SHOWN(1 << 2); // used by HtmlLayerDom

    public final int bitmask;

    Flag(int bitmask) {
      this.bitmask = bitmask;
    }
  }

  private GroupLayer parent;

  protected Transform transform;
  protected float originX, originY;
  protected float alpha;
  protected float depth;
  protected int flags;

  protected AbstractLayer() {
    transform = new Transform();
    alpha = 1;
    setFlag(Flag.VISIBLE, true);
  }

  @Override
  public void destroy() {
    if (parent() != null) {
      parent().remove(this);
    }
    setFlag(Flag.DESTROYED, true);
  }

  @Override
  public boolean destroyed() {
    return isSet(Flag.DESTROYED);
  }

  @Override
  public boolean visible() {
    return isSet(Flag.VISIBLE);
  }

  @Override
  public void setVisible(boolean visible) {
    setFlag(Flag.VISIBLE, visible);
  }

  @Override
  public float alpha() {
    return alpha;
  }

  @Override
  public void setAlpha(float alpha) {
    if (alpha < 0) {
      this.alpha = 0;
    } else if (alpha > 1) {
      this.alpha = 1;
    } else {
      this.alpha = alpha;
    }
  }

  @Override
  public float originX () {
    return originX;
  }

  @Override
  public float originY () {
    return originY;
  }

  @Override
  public void setOrigin(float x, float y) {
    this.originX = x;
    this.originY = y;
  }

  @Override
  public float depth() {
    return depth;
  }

  @Override
  public void setDepth(float depth) {
    float oldDepth = this.depth;
    if (depth != oldDepth) {
      this.depth = depth;
      if (parent != null) {
        ((ParentLayer)parent).depthChanged(this, oldDepth);
      }
    }
  }

  @Override
  public void setRotation(float angle) {
    transform.setRotation(angle);
  }

  @Override
  public void setScale(float s) {
    Asserts.checkArgument(s != 0, "Scale must be non-zero");
    transform.setScale(s);
  }

  @Override
  public void setScale(float x, float y) {
    Asserts.checkArgument(x != 0 && y != 0, "Scale must be non-zero (got x=%s, y=%s)", x, y);
    transform.setScale(x, y);
  }

  @Override
  public void setTranslation(float x, float y) {
    transform.setTranslation(x, y);
  }

  @Override
  public Transform transform() {
    return transform;
  }

  @Override
  public GroupLayer parent() {
    return parent;
  }

  public void onAdd() {
    Asserts.checkState(!destroyed(), "Illegal to use destroyed layers");
  }

  public void onRemove() {
  }

  public void setParent(GroupLayer parent) {
    this.parent = parent;
  }

  protected boolean isSet(Flag flag) {
    return (flags & flag.bitmask) != 0;
  }

  protected void setFlag(Flag flag, boolean active) {
    if (active) {
      flags |= flag.bitmask;
    } else {
      flags &= ~flag.bitmask;
    }
  }
}