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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.*;
public class PolarFilter extends TransformFilter {
public final static int RECT_TO_POLAR = 0;
public final static int POLAR_TO_RECT = 1;
public final static int INVERT_IN_CIRCLE = 2;
private int type;
private float width, height;
private float centreX, centreY;
private float radius;
public PolarFilter() {
this(RECT_TO_POLAR);
}
public PolarFilter(int type) {
this.type = type;
setEdgeAction(CLAMP);
}
public BufferedImage filter( BufferedImage src, BufferedImage dst ) {
this.width = src.getWidth();
this.height = src.getHeight();
centreX = width/2;
centreY = height/2;
radius = Math.max(centreY, centreX);
return super.filter( src, dst );
}
public void setType(int type) {
this.type = type;
}
public int getType() {
return type;
}
private float sqr(float x) {
return x*x;
}
protected void transformInverse(int x, int y, float[] out) {
float theta, t;
float m, xmax, ymax;
float r = 0;
switch (type) {
case RECT_TO_POLAR:
theta = 0;
if (x >= centreX) {
if (y > centreY) {
theta = ImageMath.PI - (float)Math.atan(((float)(x - centreX))/((float)(y - centreY)));
r = (float)Math.sqrt(sqr (x - centreX) + sqr (y - centreY));
} else if (y < centreY) {
theta = (float)Math.atan (((float)(x - centreX))/((float)(centreY - y)));
r = (float)Math.sqrt (sqr (x - centreX) + sqr (centreY - y));
} else {
theta = ImageMath.HALF_PI;
r = x - centreX;
}
} else if (x < centreX) {
if (y < centreY) {
theta = ImageMath.TWO_PI - (float)Math.atan (((float)(centreX -x))/((float)(centreY - y)));
r = (float)Math.sqrt (sqr (centreX - x) + sqr (centreY - y));
} else if (y > centreY) {
theta = ImageMath.PI + (float)Math.atan (((float)(centreX - x))/((float)(y - centreY)));
r = (float)Math.sqrt (sqr (centreX - x) + sqr (y - centreY));
} else {
theta = 1.5f * ImageMath.PI;
r = centreX - x;
}
}
if (x != centreX)
m = Math.abs (((float)(y - centreY)) / ((float)(x - centreX)));
else
m = 0;
if (m <= ((float)height / (float)width)) {
if (x == centreX) {
xmax = 0;
ymax = centreY;
} else {
xmax = centreX;
ymax = m * xmax;
}
} else {
ymax = centreY;
xmax = ymax / m;
}
out[0] = (width-1) - (width - 1)/ImageMath.TWO_PI * theta;
out[1] = height * r / radius;
break;
case POLAR_TO_RECT:
theta = x / width * ImageMath.TWO_PI;
float theta2;
if (theta >= 1.5f * ImageMath.PI)
theta2 = ImageMath.TWO_PI - theta;
else if (theta >= ImageMath.PI)
theta2 = theta - ImageMath.PI;
else if (theta >= 0.5f * ImageMath.PI)
theta2 = ImageMath.PI - theta;
else
theta2 = theta;
t = (float)Math.tan(theta2);
if (t != 0)
m = 1.0f / t;
else
m = 0;
if (m <= ((float)(height) / (float)(width))) {
if (theta2 == 0) {
xmax = 0;
ymax = centreY;
} else {
xmax = centreX;
ymax = m * xmax;
}
} else {
ymax = centreY;
xmax = ymax / m;
}
r = radius * (float)(y / (float)(height));
float nx = -r * (float)Math.sin(theta2);
float ny = r * (float)Math.cos(theta2);
if (theta >= 1.5f * ImageMath.PI) {
out[0] = (float)centreX - nx;
out[1] = (float)centreY - ny;
} else if (theta >= Math.PI) {
out[0] = (float)centreX - nx;
out[1] = (float)centreY + ny;
} else if (theta >= 0.5 * Math.PI) {
out[0] = (float)centreX + nx;
out[1] = (float)centreY + ny;
} else {
out[0] = (float)centreX + nx;
out[1] = (float)centreY - ny;
}
break;
case INVERT_IN_CIRCLE:
float dx = x-centreX;
float dy = y-centreY;
float distance2 = dx*dx+dy*dy;
out[0] = centreX + centreX*centreX * dx/distance2;
out[1] = centreY + centreY*centreY * dy/distance2;
break;
}
}
public String toString() {
return "Distort/Polar Coordinates...";
}
}
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