/*******************************************************************************
* Copyright 2012 Geoscience Australia
*
* 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 au.gov.ga.earthsci.worldwind.common.layers.delegate.filters;
import java.awt.Rectangle;
import com.jhlabs.image.MaximumFilter;
import com.jhlabs.image.PixelUtils;
/**
* Maximum (erode) filter that fixes the {@link MaximumFilter} to support
* transparency.
*
* @author Michael de Hoog (michael.dehoog@ga.gov.au)
*/
public class TransparentMaximumFilter extends MaximumFilter
{
@Override
protected int[] filterPixels(int width, int height, int[] inPixels, Rectangle transformedSpace)
{
int index = 0;
int[] outPixels = new int[width * height];
for (int y = 0; y < height; y++)
{
int yoffset = y * width;
for (int x = 0; x < width; x++)
{
int pixel = inPixels[yoffset + x] & 0xff000000;
for (int dy = -1; dy <= 1; dy++)
{
int iy = y + dy;
int ioffset;
if (0 <= iy && iy < height)
{
ioffset = iy * width;
for (int dx = -1; dx <= 1; dx++)
{
int ix = x + dx;
if (0 <= ix && ix < width)
{
pixel = PixelUtils.combinePixels(pixel, inPixels[ioffset + ix], PixelUtils.MAX);
}
}
}
}
outPixels[index++] = pixel;
}
}
return outPixels;
}
}