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/*
Copyright 2006 Jerry Huxtable
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.jhlabs.image;
import java.awt.*;
import java.awt.image.*;
/**
* An abstract superclass for filters which distort images in some way. The subclass only needs to override
* two methods to provide the mapping between source and destination pixels.
*/
public abstract class TransformFilter extends AbstractBufferedImageOp {
public final static int ZERO = 0;
public final static int CLAMP = 1;
public final static int WRAP = 2;
public final static int NEAREST_NEIGHBOUR = 0;
public final static int BILINEAR = 1;
protected int edgeAction = ZERO;
protected int interpolation = BILINEAR;
protected Rectangle transformedSpace;
protected Rectangle originalSpace;
public void setEdgeAction(int edgeAction) {
this.edgeAction = edgeAction;
}
public int getEdgeAction() {
return edgeAction;
}
public void setInterpolation(int interpolation) {
this.interpolation = interpolation;
}
public int getInterpolation() {
return interpolation;
}
protected abstract void transformInverse(int x, int y, float[] out);
protected void transformSpace(Rectangle rect) {
}
public BufferedImage filter( BufferedImage src, BufferedImage dst ) {
int width = src.getWidth();
int height = src.getHeight();
int type = src.getType();
WritableRaster srcRaster = src.getRaster();
originalSpace = new Rectangle(0, 0, width, height);
transformedSpace = new Rectangle(0, 0, width, height);
transformSpace(transformedSpace);
if ( dst == null ) {
ColorModel dstCM = src.getColorModel();
dst = new BufferedImage(dstCM, dstCM.createCompatibleWritableRaster(transformedSpace.width, transformedSpace.height), dstCM.isAlphaPremultiplied(), null);
}
WritableRaster dstRaster = dst.getRaster();
int[] inPixels = getRGB( src, 0, 0, width, height, null );
if ( interpolation == NEAREST_NEIGHBOUR )
return filterPixelsNN( dst, width, height, inPixels, transformedSpace );
int srcWidth = width;
int srcHeight = height;
int srcWidth1 = width-1;
int srcHeight1 = height-1;
int outWidth = transformedSpace.width;
int outHeight = transformedSpace.height;
int outX, outY;
int index = 0;
int[] outPixels = new int[outWidth];
outX = transformedSpace.x;
outY = transformedSpace.y;
float[] out = new float[2];
for (int y = 0; y < outHeight; y++) {
for (int x = 0; x < outWidth; x++) {
transformInverse(outX+x, outY+y, out);
int srcX = (int)Math.floor( out[0] );
int srcY = (int)Math.floor( out[1] );
float xWeight = out[0]-srcX;
float yWeight = out[1]-srcY;
int nw, ne, sw, se;
if ( srcX >= 0 && srcX < srcWidth1 && srcY >= 0 && srcY < srcHeight1) {
// Easy case, all corners are in the image
int i = srcWidth*srcY + srcX;
nw = inPixels[i];
ne = inPixels[i+1];
sw = inPixels[i+srcWidth];
se = inPixels[i+srcWidth+1];
} else {
// Some of the corners are off the image
nw = getPixel( inPixels, srcX, srcY, srcWidth, srcHeight );
ne = getPixel( inPixels, srcX+1, srcY, srcWidth, srcHeight );
sw = getPixel( inPixels, srcX, srcY+1, srcWidth, srcHeight );
se = getPixel( inPixels, srcX+1, srcY+1, srcWidth, srcHeight );
}
outPixels[x] = ImageMath.bilinearInterpolate(xWeight, yWeight, nw, ne, sw, se);
}
setRGB( dst, 0, y, transformedSpace.width, 1, outPixels );
}
return dst;
}
final private int getPixel( int[] pixels, int x, int y, int width, int height ) {
if (x < 0 || x >= width || y < 0 || y >= height) {
switch (edgeAction) {
case ZERO:
default:
return 0;
case WRAP:
return pixels[(ImageMath.mod(y, height) * width) + ImageMath.mod(x, width)];
case CLAMP:
return pixels[(ImageMath.clamp(y, 0, height-1) * width) + ImageMath.clamp(x, 0, width-1)];
}
}
return pixels[ y*width+x ];
}
protected BufferedImage filterPixelsNN( BufferedImage dst, int width, int height, int[] inPixels, Rectangle transformedSpace ) {
int srcWidth = width;
int srcHeight = height;
int outWidth = transformedSpace.width;
int outHeight = transformedSpace.height;
int outX, outY, srcX, srcY;
int[] outPixels = new int[outWidth];
outX = transformedSpace.x;
outY = transformedSpace.y;
int[] rgb = new int[4];
float[] out = new float[2];
for (int y = 0; y < outHeight; y++) {
for (int x = 0; x < outWidth; x++) {
transformInverse(outX+x, outY+y, out);
srcX = (int)out[0];
srcY = (int)out[1];
// int casting rounds towards zero, so we check out[0] < 0, not srcX < 0
if (out[0] < 0 || srcX >= srcWidth || out[1] < 0 || srcY >= srcHeight) {
int p;
switch (edgeAction) {
case ZERO:
default:
p = 0;
break;
case WRAP:
p = inPixels[(ImageMath.mod(srcY, srcHeight) * srcWidth) + ImageMath.mod(srcX, srcWidth)];
break;
case CLAMP:
p = inPixels[(ImageMath.clamp(srcY, 0, srcHeight-1) * srcWidth) + ImageMath.clamp(srcX, 0, srcWidth-1)];
break;
}
outPixels[x] = p;
} else {
int i = srcWidth*srcY + srcX;
rgb[0] = inPixels[i];
outPixels[x] = inPixels[i];
}
}
setRGB( dst, 0, y, transformedSpace.width, 1, outPixels );
}
return dst;
}
}
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