Gradient effects
//package edu.purdue.touch.util;
import java.awt.Color;
/**
*
* <p>
* There are a number of defined gradient types (look at the static fields), but
* you can create any gradient you like by using either of the following
* functions:
* <ul>
* <li>public static Color[] createMultiGradient(Color[] colors, int numSteps)</li>
* <li>public static Color[] createGradient(Color one, Color two, int numSteps)</li>
* </ul>
* You can then assign an arbitrary Color[] object to the HeatMap as follows:
*
* <pre>
* myHeatMap.updateGradient(Gradient.createMultiGradient(new Color[] { Color.red,
* Color.white, Color.blue }, 256));
* </pre>
*
* </p>
*
* <hr />
* <p>
* <strong>Copyright:</strong> Copyright (c) 2007, 2008
* </p>
*
* <p>
* HeatMap is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option) any later
* version.
* </p>
*
* <p>
* HeatMap is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
* </p>
*
* <p>
* You should have received a copy of the GNU General Public License along with
* HeatMap; if not, write to the Free Software Foundation, Inc., 51 Franklin St,
* Fifth Floor, Boston, MA 02110-1301 USA
* </p>
*
* @author Matthew Beckler (matthew@mbeckler.org)
* @author Josh Hayes-Sheen (grey@grevian.org), Converted to use BufferedImage.
* @author J. Keller (jpaulkeller@gmail.com), Added transparency (alpha)
* support, data ordering bug fix.
* @version 1.6
*/
public class Gradient {
/**
* Produces a gradient using the University of Minnesota's school colors,
* from maroon (low) to gold (high)
*/
public final static Color[] GRADIENT_MAROON_TO_GOLD = createGradient(
new Color(0xA0, 0x00, 0x00), new Color(0xFF, 0xFF, 0x00), 500);
/**
* Produces a gradient from blue (low) to red (high)
*/
public final static Color[] GRADIENT_BLUE_TO_RED = createGradient(
Color.BLUE, Color.RED, 500);
/**
* Produces a gradient from black (low) to white (high)
*/
public final static Color[] GRADIENT_BLACK_TO_WHITE = createGradient(
Color.BLACK, Color.WHITE, 500);
/**
* Produces a gradient from red (low) to green (high)
*/
public final static Color[] GRADIENT_RED_TO_GREEN = createGradient(
Color.RED, Color.GREEN, 500);
/**
* Produces a gradient through green, yellow, orange, red
*/
public final static Color[] GRADIENT_GREEN_YELLOW_ORANGE_RED = createMultiGradient(
new Color[] { Color.green, Color.yellow, Color.orange, Color.red },
500);
/**
* Produces a gradient through the rainbow: violet, blue, green, yellow,
* orange, red
*/
public final static Color[] GRADIENT_RAINBOW = createMultiGradient(
new Color[] { new Color(181, 32, 255), Color.blue, Color.green,
Color.yellow, Color.orange, Color.red }, 500);
/**
* Produces a gradient for hot things (black, red, orange, yellow, white)
*/
public final static Color[] GRADIENT_HOT = createMultiGradient(new Color[] {
Color.black, new Color(87, 0, 0), Color.red, Color.orange,
Color.yellow, Color.white }, 500);
/**
* Produces a different gradient for hot things (black, brown, orange,
* white)
*/
public final static Color[] GRADIENT_HEAT = createMultiGradient(
new Color[] { Color.black, new Color(105, 0, 0),
new Color(192, 23, 0), new Color(255, 150, 38), Color.white },
500);
/**
* Produces a gradient through red, orange, yellow
*/
public final static Color[] GRADIENT_ROY = createMultiGradient(new Color[] {
Color.red, Color.orange, Color.yellow }, 500);
/**
* Creates an array of Color objects for use as a gradient, using a linear
* interpolation between the two specified colors.
*
* @param one
* Color used for the bottom of the gradient
* @param two
* Color used for the top of the gradient
* @param numSteps
* The number of steps in the gradient. 250 is a good number.
*/
public static Color[] createGradient(final Color one, final Color two,
final int numSteps) {
int r1 = one.getRed();
int g1 = one.getGreen();
int b1 = one.getBlue();
int a1 = one.getAlpha();
int r2 = two.getRed();
int g2 = two.getGreen();
int b2 = two.getBlue();
int a2 = two.getAlpha();
int newR = 0;
int newG = 0;
int newB = 0;
int newA = 0;
Color[] gradient = new Color[numSteps];
double iNorm;
for (int i = 0; i < numSteps; i++) {
iNorm = i / (double) numSteps; // a normalized [0:1] variable
newR = (int) (r1 + iNorm * (r2 - r1));
newG = (int) (g1 + iNorm * (g2 - g1));
newB = (int) (b1 + iNorm * (b2 - b1));
newA = (int) (a1 + iNorm * (a2 - a1));
gradient[i] = new Color(newR, newG, newB, newA);
}
return gradient;
}
/**
* Creates an array of Color objects for use as a gradient, using an array
* of Color objects. It uses a linear interpolation between each pair of
* points. The parameter numSteps defines the total number of colors in the
* returned array, not the number of colors per segment.
*
* @param colors
* An array of Color objects used for the gradient. The Color at
* index 0 will be the lowest color.
* @param numSteps
* The number of steps in the gradient. 250 is a good number.
*/
public static Color[] createMultiGradient(Color[] colors, int numSteps) {
// we assume a linear gradient, with equal spacing between colors
// The final gradient will be made up of n 'sections', where n =
// colors.length - 1
int numSections = colors.length - 1;
int gradientIndex = 0; // points to the next open spot in the final
// gradient
Color[] gradient = new Color[numSteps];
Color[] temp;
if (numSections <= 0) {
throw new IllegalArgumentException(
"You must pass in at least 2 colors in the array!");
}
for (int section = 0; section < numSections; section++) {
// we divide the gradient into (n - 1) sections, and do a regular
// gradient for each
temp = createGradient(colors[section], colors[section + 1],
numSteps / numSections);
for (int i = 0; i < temp.length; i++) {
// copy the sub-gradient into the overall gradient
gradient[gradientIndex++] = temp[i];
}
}
if (gradientIndex < numSteps) {
// The rounding didn't work out in our favor, and there is at least
// one unfilled slot in the gradient[] array.
// We can just copy the final color there
for (/* nothing to initialize */; gradientIndex < numSteps; gradientIndex++) {
gradient[gradientIndex] = colors[colors.length - 1];
}
}
return gradient;
}
}
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