/*******************************************************************************
* Breakout Cave Survey Visualizer
*
* Copyright (C) 2014 James Edwards
*
* jedwards8 at fastmail dot fm
*
* This program 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.
*
* This program 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.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*******************************************************************************/
package org.breakout.awt;
import java.awt.Color;
import java.awt.PaintContext;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
import java.awt.geom.Rectangle2D;
import java.awt.image.ColorModel;
import java.awt.image.DataBufferInt;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.SinglePixelPackedSampleModel;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import org.breakout.awt.MultipleGradientPaint.ColorSpaceType;
import org.breakout.awt.MultipleGradientPaint.CycleMethod;
/**
* This is the superclass for all PaintContexts which use a multiple color
* gradient to fill in their raster. It provides the actual color interpolation
* functionality. Subclasses only have to deal with using the gradient to fill
* pixels in a raster.
*
* @author Nicholas Talian, Vincent Hardy, Jim Graham, Jerry Evans
*/
abstract class MultipleGradientPaintContext implements PaintContext {
/** Color model used if gradient colors are all opaque. */
private static ColorModel xrgbmodel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
/** The cached ColorModel. */
protected static ColorModel cachedModel;
/** The cached raster, which is reusable among instances. */
protected static WeakReference<Raster> cached;
/** Color space conversion lookup tables. */
private static final int SRGBtoLinearRGB[] = new int[256];
private static final int LinearRGBtoSRGB[] = new int[256];
static {
// build the tables
for (int k = 0; k < 256; k++) {
SRGBtoLinearRGB[k] = convertSRGBtoLinearRGB(k);
LinearRGBtoSRGB[k] = convertLinearRGBtoSRGB(k);
}
}
/**
* Constant number of max colors between any 2 arbitrary colors. Used for
* creating and indexing gradients arrays.
*/
protected static final int GRADIENT_SIZE = 256;
protected static final int GRADIENT_SIZE_INDEX = GRADIENT_SIZE - 1;
/**
* Maximum length of the fast single-array. If the estimated array size is
* greater than this, switch over to the slow lookup method. No particular
* reason for choosing this number, but it seems to provide satisfactory
* performance for the common case (fast lookup).
*/
private static final int MAX_GRADIENT_ARRAY_SIZE = 5000;
/**
* Helper function to convert a color component in linear RGB space to SRGB
* space. Used to build a static lookup table.
*/
private static int convertLinearRGBtoSRGB(int color) {
float input, output;
input = color / 255.0f;
if (input <= 0.0031308) {
output = input * 12.92f;
} else {
output = 1.055f *
(float) Math.pow(input, 1.0 / 2.4) - 0.055f;
}
return Math.round(output * 255.0f);
}
/**
* Helper function to convert a color component in sRGB space to linear RGB
* space. Used to build a static lookup table.
*/
private static int convertSRGBtoLinearRGB(int color) {
float input, output;
input = color / 255.0f;
if (input <= 0.04045f) {
output = input / 12.92f;
} else {
output = (float) Math.pow((input + 0.055) / 1.055, 2.4);
}
return Math.round(output * 255.0f);
}
/**
* Took this cacheRaster code from GradientPaint. It appears to recycle
* rasters for use by any other instance, as long as they are sufficiently
* large.
*/
private static synchronized Raster getCachedRaster(ColorModel cm,
int w, int h) {
if (cm == cachedModel) {
if (cached != null) {
Raster ras = cached.get();
if (ras != null &&
ras.getWidth() >= w &&
ras.getHeight() >= h) {
cached = null;
return ras;
}
}
}
return cm.createCompatibleWritableRaster(w, h);
}
/**
* Took this cacheRaster code from GradientPaint. It appears to recycle
* rasters for use by any other instance, as long as they are sufficiently
* large.
*/
private static synchronized void putCachedRaster(ColorModel cm,
Raster ras) {
if (cached != null) {
Raster cras = cached.get();
if (cras != null) {
int cw = cras.getWidth();
int ch = cras.getHeight();
int iw = ras.getWidth();
int ih = ras.getHeight();
if (cw >= iw && ch >= ih) {
return;
}
if (cw * ch >= iw * ih) {
return;
}
}
}
cachedModel = cm;
cached = new WeakReference<Raster>(ras);
}
/**
* The PaintContext's ColorModel. This is ARGB if colors are not all opaque,
* otherwise it is RGB.
*/
protected ColorModel model;
/** Raster is reused whenever possible. */
protected Raster saved;
/** The method to use when painting out of the gradient bounds. */
protected CycleMethod cycleMethod;
/** The ColorSpace in which to perform the interpolation */
protected ColorSpaceType colorSpace;
/** Elements of the inverse transform matrix. */
protected float a00, a01, a10, a11, a02, a12;
/**
* This boolean specifies wether we are in simple lookup mode, where an
* input value between 0 and 1 may be used to directly index into a single
* array of gradient colors. If this boolean value is false, then we have to
* use a 2-step process where we have to determine which gradient array we
* fall into, then determine the index into that array.
*/
protected boolean isSimpleLookup;
/**
* Size of gradients array for scaling the 0-1 index when looking up colors
* the fast way.
*/
protected int fastGradientArraySize;
/**
* Array which contains the interpolated color values for each interval,
* used by calculateSingleArrayGradient(). It is protected for possible
* direct access by subclasses.
*/
protected int[] gradient;
/**
* Array of gradient arrays, one array for each interval. Used by
* calculateMultipleArrayGradient().
*/
private int[][] gradients;
/** Normalized intervals array. */
private float[] normalizedIntervals;
/** Fractions array. */
private float[] fractions;
/** Used to determine if gradient colors are all opaque. */
private int transparencyTest;
/**
* Constructor for MultipleGradientPaintContext superclass.
*/
protected MultipleGradientPaintContext(MultipleGradientPaint mgp,
ColorModel cm,
Rectangle deviceBounds,
Rectangle2D userBounds,
AffineTransform t,
RenderingHints hints,
float[] fractions,
Color[] colors,
CycleMethod cycleMethod2,
ColorSpaceType colorSpace2) {
if (deviceBounds == null) {
throw new NullPointerException("Device bounds cannot be null");
}
if (userBounds == null) {
throw new NullPointerException("User bounds cannot be null");
}
if (t == null) {
throw new NullPointerException("Transform cannot be null");
}
if (hints == null) {
throw new NullPointerException("RenderingHints cannot be null");
}
// The inverse transform is needed to go from device to user space.
// Get all the components of the inverse transform matrix.
AffineTransform tInv;
try {
// the following assumes that the caller has copied the incoming
// transform and is not concerned about it being modified
t.invert();
tInv = t;
} catch (NoninvertibleTransformException e) {
// just use identity transform in this case; better to show
// (incorrect) results than to throw an exception and/or no-op
tInv = new AffineTransform();
}
double m[] = new double[6];
tInv.getMatrix(m);
a00 = (float) m[0];
a10 = (float) m[1];
a01 = (float) m[2];
a11 = (float) m[3];
a02 = (float) m[4];
a12 = (float) m[5];
// copy some flags
cycleMethod = cycleMethod2;
colorSpace = colorSpace2;
// we can avoid copying this array since we do not modify its values
this.fractions = fractions;
// note that only one of these values can ever be non-null (we either
// store the fast gradient array or the slow one, but never both
// at the same time)
int[] gradient = mgp.gradient != null ? mgp.gradient.get() : null;
int[][] gradients = mgp.gradients != null ? mgp.gradients.get() : null;
if (gradient == null && gradients == null) {
// we need to (re)create the appropriate values
calculateLookupData(colors);
// now cache the calculated values in the
// MultipleGradientPaint instance for future use
mgp.model = model;
mgp.normalizedIntervals = normalizedIntervals;
mgp.isSimpleLookup = isSimpleLookup;
if (isSimpleLookup) {
// only cache the fast array
mgp.fastGradientArraySize = fastGradientArraySize;
mgp.gradient = new SoftReference<int[]>(this.gradient);
} else {
// only cache the slow array
mgp.gradients = new SoftReference<int[][]>(this.gradients);
}
} else {
// use the values cached in the MultipleGradientPaint instance
model = mgp.model;
normalizedIntervals = mgp.normalizedIntervals;
isSimpleLookup = mgp.isSimpleLookup;
this.gradient = gradient;
fastGradientArraySize = mgp.fastGradientArraySize;
this.gradients = gradients;
}
}
/**
* This function is the meat of this class. It calculates an array of
* gradient colors based on an array of fractions and color values at those
* fractions.
*/
private void calculateLookupData(Color[] colors) {
Color[] normalizedColors;
if (colorSpace == ColorSpaceType.LINEAR_RGB) {
// create a new colors array
normalizedColors = new Color[colors.length];
// convert the colors using the lookup table
for (int i = 0; i < colors.length; i++) {
int argb = colors[i].getRGB();
int a = argb >>> 24;
int r = SRGBtoLinearRGB[argb >> 16 & 0xff];
int g = SRGBtoLinearRGB[argb >> 8 & 0xff];
int b = SRGBtoLinearRGB[argb & 0xff];
normalizedColors[i] = new Color(r, g, b, a);
}
} else {
// we can just use this array by reference since we do not
// modify its values in the case of SRGB
normalizedColors = colors;
}
// this will store the intervals (distances) between gradient stops
normalizedIntervals = new float[fractions.length - 1];
// convert from fractions into intervals
for (int i = 0; i < normalizedIntervals.length; i++) {
// interval distance is equal to the difference in positions
normalizedIntervals[i] = fractions[i + 1] - fractions[i];
}
// initialize to be fully opaque for ANDing with colors
transparencyTest = 0xff000000;
// array of interpolation arrays
gradients = new int[normalizedIntervals.length][];
// find smallest interval
float Imin = 1;
for (int i = 0; i < normalizedIntervals.length; i++) {
Imin = Imin > normalizedIntervals[i] ? normalizedIntervals[i] : Imin;
}
// Estimate the size of the entire gradients array.
// This is to prevent a tiny interval from causing the size of array
// to explode. If the estimated size is too large, break to using
// separate arrays for each interval, and using an indexing scheme at
// look-up time.
int estimatedSize = 0;
for (int i = 0; i < normalizedIntervals.length; i++) {
estimatedSize += normalizedIntervals[i] / Imin * GRADIENT_SIZE;
}
if (estimatedSize > MAX_GRADIENT_ARRAY_SIZE) {
// slow method
calculateMultipleArrayGradient(normalizedColors);
} else {
// fast method
calculateSingleArrayGradient(normalizedColors, Imin);
}
// use the most "economical" model
if (transparencyTest >>> 24 == 0xff) {
model = xrgbmodel;
} else {
model = ColorModel.getRGBdefault();
}
}
/**
* SLOW LOOKUP METHOD
*
* This method calculates the gradient color values for each interval and
* places each into its own 255 size array. The arrays are stored in
* gradients[][]. (255 is used because this is the maximum number of unique
* colors between 2 arbitrary colors in a 24 bit color system.)
*
* This method uses the minimum amount of space (only 255 * number of
* intervals), but it aggravates the lookup procedure, because now we have
* to find out which interval to select, then calculate the index within
* that interval. This causes a significant performance hit, because it
* requires this calculation be done for every point in the rendering loop.
*
* For those of you who are interested, this is a classic example of the
* time-space tradeoff.
*/
private void calculateMultipleArrayGradient(Color[] colors) {
// set the flag so we know later it is a non-simple lookup
isSimpleLookup = false;
// 2 colors to interpolate
int rgb1, rgb2;
// for every interval (transition between 2 colors)
for (int i = 0; i < gradients.length; i++) {
// create an array of the maximum theoretical size for
// each interval
gradients[i] = new int[GRADIENT_SIZE];
// get the the 2 colors
rgb1 = colors[i].getRGB();
rgb2 = colors[i + 1].getRGB();
// fill this array with the colors in between rgb1 and rgb2
interpolate(rgb1, rgb2, gradients[i]);
// if the colors are opaque, transparency should still
// be 0xff000000
transparencyTest &= rgb1;
transparencyTest &= rgb2;
}
// if interpolation occurred in Linear RGB space, convert the
// gradients back to SRGB using the lookup table
if (colorSpace == ColorSpaceType.LINEAR_RGB) {
for (int j = 0; j < gradients.length; j++) {
for (int i = 0; i < gradients[j].length; i++) {
gradients[j][i] = convertEntireColorLinearRGBtoSRGB(gradients[j][i]);
}
}
}
}
/**
* FAST LOOKUP METHOD
*
* This method calculates the gradient color values and places them in a
* single int array, gradient[]. It does this by allocating space for each
* interval based on its size relative to the smallest interval in the
* array. The smallest interval is allocated 255 interpolated values (the
* maximum number of unique in-between colors in a 24 bit color system), and
* all other intervals are allocated size = (255 * the ratio of their size
* to the smallest interval).
*
* This scheme expedites a speedy retrieval because the colors are
* distributed along the array according to their user-specified
* distribution. All that is needed is a relative index from 0 to 1.
*
* The only problem with this method is that the possibility exists for the
* array size to balloon in the case where there is a disproportionately
* small gradient interval. In this case the other intervals will be
* allocated huge space, but much of that data is redundant. We thus need to
* use the space conserving scheme below.
*
* @param Imin
* the size of the smallest interval
*/
private void calculateSingleArrayGradient(Color[] colors, float Imin) {
// set the flag so we know later it is a simple (fast) lookup
isSimpleLookup = true;
// 2 colors to interpolate
int rgb1, rgb2;
// the eventual size of the single array
int gradientsTot = 1;
// for every interval (transition between 2 colors)
for (int i = 0; i < gradients.length; i++) {
// create an array whose size is based on the ratio to the
// smallest interval
int nGradients = (int) (normalizedIntervals[i] / Imin * 255f);
gradientsTot += nGradients;
gradients[i] = new int[nGradients];
// the 2 colors (keyframes) to interpolate between
rgb1 = colors[i].getRGB();
rgb2 = colors[i + 1].getRGB();
// fill this array with the colors in between rgb1 and rgb2
interpolate(rgb1, rgb2, gradients[i]);
// if the colors are opaque, transparency should still
// be 0xff000000
transparencyTest &= rgb1;
transparencyTest &= rgb2;
}
// put all gradients in a single array
gradient = new int[gradientsTot];
int curOffset = 0;
for (int i = 0; i < gradients.length; i++) {
System.arraycopy(gradients[i], 0, gradient,
curOffset, gradients[i].length);
curOffset += gradients[i].length;
}
gradient[gradient.length - 1] = colors[colors.length - 1].getRGB();
// if interpolation occurred in Linear RGB space, convert the
// gradients back to sRGB using the lookup table
if (colorSpace == ColorSpaceType.LINEAR_RGB) {
for (int i = 0; i < gradient.length; i++) {
gradient[i] = convertEntireColorLinearRGBtoSRGB(gradient[i]);
}
}
fastGradientArraySize = gradient.length - 1;
}
/**
* Yet another helper function. This one extracts the color components of an
* integer RGB triple, converts them from LinearRGB to SRGB, then recompacts
* them into an int.
*/
private int convertEntireColorLinearRGBtoSRGB(int rgb) {
// color components
int a1, r1, g1, b1;
// extract red, green, blue components
a1 = rgb >> 24 & 0xff;
r1 = rgb >> 16 & 0xff;
g1 = rgb >> 8 & 0xff;
b1 = rgb & 0xff;
// use the lookup table
r1 = LinearRGBtoSRGB[r1];
g1 = LinearRGBtoSRGB[g1];
b1 = LinearRGBtoSRGB[b1];
// re-compact the components
return a1 << 24 |
r1 << 16 |
g1 << 8 | b1;
}
/**
* {@inheritDoc}
*/
@Override
public final void dispose() {
if (saved != null) {
putCachedRaster(model, saved);
saved = null;
}
}
protected abstract void fillRaster(int pixels[], int off, int adjust,
int x, int y, int w, int h);
/**
* {@inheritDoc}
*/
@Override
public final ColorModel getColorModel() {
return model;
}
/**
* {@inheritDoc}
*/
@Override
public final Raster getRaster(int x, int y, int w, int h) {
// If working raster is big enough, reuse it. Otherwise,
// build a large enough new one.
Raster raster = saved;
if (raster == null ||
raster.getWidth() < w || raster.getHeight() < h) {
raster = getCachedRaster(model, w, h);
saved = raster;
}
// Access raster internal int array. Because we use a DirectColorModel,
// we know the DataBuffer is of type DataBufferInt and the SampleModel
// is SinglePixelPackedSampleModel.
// Adjust for initial offset in DataBuffer and also for the scanline
// stride.
DataBufferInt rasterDB = (DataBufferInt) raster.getDataBuffer();
int[] pixels = rasterDB.getBankData()[0];
int off = rasterDB.getOffset();
int scanlineStride = ((SinglePixelPackedSampleModel) raster.getSampleModel()).getScanlineStride();
int adjust = scanlineStride - w;
fillRaster(pixels, off, adjust, x, y, w, h); // delegate to subclass
return raster;
}
/**
* Helper function to index into the gradients array. This is necessary
* because each interval has an array of colors with uniform size 255.
* However, the color intervals are not necessarily of uniform length, so a
* conversion is required.
*
* @param position
* the unmanipulated position, which will be mapped into the
* range 0 to 1
* @returns integer color to display
*/
protected final int indexIntoGradientsArrays(float position) {
// first, manipulate position value depending on the cycle method
if (cycleMethod == CycleMethod.NO_CYCLE) {
if (position > 1) {
// upper bound is 1
position = 1;
} else if (position < 0) {
// lower bound is 0
position = 0;
}
} else if (cycleMethod == CycleMethod.REPEAT) {
// get the fractional part
// (modulo behavior discards integer component)
position = position - (int) position;
// position should now be between -1 and 1
if (position < 0) {
// force it to be in the range 0-1
position = position + 1;
}
} else { // cycleMethod == CycleMethod.REFLECT
if (position < 0) {
// take absolute value
position = -position;
}
// get the integer part
int part = (int) position;
// get the fractional part
position = position - part;
if ((part & 1) == 1) {
// integer part is odd, get reflected color instead
position = 1 - position;
}
}
// now, get the color based on this 0-1 position...
if (isSimpleLookup) {
// easy to compute: just scale index by array size
return gradient[(int) (position * fastGradientArraySize)];
} else {
// more complicated computation, to save space
// for all the gradient interval arrays
for (int i = 0; i < gradients.length; i++) {
if (position < fractions[i + 1]) {
// this is the array we want
float delta = position - fractions[i];
// this is the interval we want
int index = (int) (delta / normalizedIntervals[i]
* GRADIENT_SIZE_INDEX);
return gradients[i][index];
}
}
}
return gradients[gradients.length - 1][GRADIENT_SIZE_INDEX];
}
/**
* Yet another helper function. This one linearly interpolates between 2
* colors, filling up the output array.
*
* @param rgb1
* the start color
* @param rgb2
* the end color
* @param output
* the output array of colors; must not be null
*/
private void interpolate(int rgb1, int rgb2, int[] output) {
// color components
int a1, r1, g1, b1, da, dr, dg, db;
// step between interpolated values
float stepSize = 1.0f / output.length;
// extract color components from packed integer
a1 = rgb1 >> 24 & 0xff;
r1 = rgb1 >> 16 & 0xff;
g1 = rgb1 >> 8 & 0xff;
b1 = rgb1 & 0xff;
// calculate the total change in alpha, red, green, blue
da = (rgb2 >> 24 & 0xff) - a1;
dr = (rgb2 >> 16 & 0xff) - r1;
dg = (rgb2 >> 8 & 0xff) - g1;
db = (rgb2 & 0xff) - b1;
// for each step in the interval calculate the in-between color by
// multiplying the normalized current position by the total color
// change (0.5 is added to prevent truncation round-off error)
for (int i = 0; i < output.length; i++) {
output[i] = (int) (a1 + i * da * stepSize + 0.5) << 24 |
(int) (r1 + i * dr * stepSize + 0.5) << 16 |
(int) (g1 + i * dg * stepSize + 0.5) << 8 |
(int) (b1 + i * db * stepSize + 0.5);
}
}
}