/*

* Copyright (c) 2002 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:

*

*/

package javax.microedition.lcdui.game;

import javax.microedition.lcdui.Graphics;

import java.util.Vector;

public class LayerManager

{

    private Vector iLayers;

    private int iViewX;

    private int iViewY;

    private int iViewWidth  = Integer.MAX_VALUE;

    private int iViewHeight = Integer.MAX_VALUE;

    public LayerManager()

    {

        iLayers = new Vector();

    }

    public void append(Layer aLayer)

    {

        remove(aLayer);

        iLayers.addElement(aLayer);

    }

    public void insert(Layer aLayer,int aIndex)

    {

        if (aLayer == null)

        {

            throw new NullPointerException();

        }

        int indexLimit = iLayers.size();

        if (aIndex<0 || aIndex>indexLimit)

        {

            throw new IndexOutOfBoundsException();

        }

        indexLimit--;

        if (aIndex>indexLimit && iLayers.contains(aLayer))

        {

            throw new IndexOutOfBoundsException();

        }

        remove(aLayer);

        iLayers.insertElementAt(aLayer,aIndex);

    }

    public void remove(Layer aLayer)

    {

        if (aLayer == null)

        {

            throw new NullPointerException();

        }

        iLayers.removeElement(aLayer);

    }

    public Layer getLayerAt(int aIndex)

    {

        return (Layer)iLayers.elementAt(aIndex);

    }

    public int getSize()

    {

        return iLayers.size();

    }

    public void setViewWindow(int aX,int aY,int aWidth,int aHeight)

    {

        if (aWidth<0 || aHeight<0)

        {

            throw new IllegalArgumentException("Width or height is less than 0");

        }

        iViewX=aX;

        iViewY=aY;

        iViewWidth=aWidth;

        iViewHeight=aHeight;

    }

    public void paint(Graphics aGraphics,int aX,int aY)

    {

        // save Graphics clip and translate

        final int clipX = aGraphics.getClipX();

        final int clipY = aGraphics.getClipY();

        final int clipWidth = aGraphics.getClipWidth();

        final int clipHeight = aGraphics.getClipHeight();

        final int transX = aGraphics.getTranslateX();

        final int transY = aGraphics.getTranslateY();

        // intersect Graphics clip region with View Window

            aGraphics.clipRect(aX,aY,iViewWidth,iViewHeight);

        // translate the graphics object so the point (aX,aY) corresponds to

        // the location of the viewWindow in the coordinate system of the LayerManager.

        aGraphics.translate(-iViewX,-iViewY);

        // paint visible Layers

        final int size = iLayers.size();

        for (int i=size-1; i>=0; i--)

        {

            final Layer layer = getLayerAt(i);

            if (layerVisible(aGraphics,layer,aX,aY))

            {

                aGraphics.translate(aX,aY);

                layer.paint(aGraphics);

                aGraphics.translate(-aX,-aY);

            }

        }

        // restore Graphics translation

        // because translation is concatenated, we need to translate back to 0,0 first

        aGraphics.translate(-aGraphics.getTranslateX(), -aGraphics.getTranslateY());

        // now back to original translation, per spec

        aGraphics.translate(transX,transY);

        // restore Graphics clip - must do after restore translation

        aGraphics.setClip(clipX,clipY,clipWidth,clipHeight);

    }

    /**

     * Check if Layer is visible in Graphics clip region.

     */

    private boolean layerVisible(Graphics aGraphics, Layer aLayer, int aX, int aY)

    {

        final int clipTlX = aGraphics.getClipX();

        final int clipTlY = aGraphics.getClipY();

        final int clipBrX = clipTlX + aGraphics.getClipWidth();

        final int clipBrY = clipTlY + aGraphics.getClipHeight();

        final int layerTlX = aLayer.getX() + aX;

        final int layerTlY = aLayer.getY() + aY;

        final int layerBrX = layerTlX + aLayer.getWidth();

        final int layerBrY = layerTlY + aLayer.getHeight();

        return(!(clipBrX<=layerTlX || clipBrY<=layerTlY || clipTlX>=layerBrX || clipTlY>=layerBrY));

    }

}