| /* |
| * Copyright (c) 2006, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.awt; |
| |
| import java.awt.MultipleGradientPaint.CycleMethod; |
| import java.awt.MultipleGradientPaint.ColorSpaceType; |
| import java.awt.geom.AffineTransform; |
| import java.awt.geom.Point2D; |
| import java.awt.geom.Rectangle2D; |
| import java.awt.image.ColorModel; |
| |
| /** |
| * Provides the actual implementation for the LinearGradientPaint. |
| * This is where the pixel processing is done. |
| * |
| * @see java.awt.LinearGradientPaint |
| * @see java.awt.PaintContext |
| * @see java.awt.Paint |
| * @author Nicholas Talian, Vincent Hardy, Jim Graham, Jerry Evans |
| */ |
| final class LinearGradientPaintContext extends MultipleGradientPaintContext { |
| |
| /** |
| * The following invariants are used to process the gradient value from |
| * a device space coordinate, (X, Y): |
| * g(X, Y) = dgdX*X + dgdY*Y + gc |
| */ |
| private float dgdX, dgdY, gc; |
| |
| /** |
| * Constructor for LinearGradientPaintContext. |
| * |
| * @param paint the {@code LinearGradientPaint} from which this context |
| * is created |
| * @param cm {@code ColorModel} that receives |
| * the {@code Paint} data. This is used only as a hint. |
| * @param deviceBounds the device space bounding box of the |
| * graphics primitive being rendered |
| * @param userBounds the user space bounding box of the |
| * graphics primitive being rendered |
| * @param t the {@code AffineTransform} from user |
| * space into device space (gradientTransform should be |
| * concatenated with this) |
| * @param hints the hints that the context object uses to choose |
| * between rendering alternatives |
| * @param start gradient start point, in user space |
| * @param end gradient end point, in user space |
| * @param fractions the fractions specifying the gradient distribution |
| * @param colors the gradient colors |
| * @param cycleMethod either NO_CYCLE, REFLECT, or REPEAT |
| * @param colorSpace which colorspace to use for interpolation, |
| * either SRGB or LINEAR_RGB |
| */ |
| LinearGradientPaintContext(LinearGradientPaint paint, |
| ColorModel cm, |
| Rectangle deviceBounds, |
| Rectangle2D userBounds, |
| AffineTransform t, |
| RenderingHints hints, |
| Point2D start, |
| Point2D end, |
| float[] fractions, |
| Color[] colors, |
| CycleMethod cycleMethod, |
| ColorSpaceType colorSpace) |
| { |
| super(paint, cm, deviceBounds, userBounds, t, hints, fractions, |
| colors, cycleMethod, colorSpace); |
| |
| // A given point in the raster should take on the same color as its |
| // projection onto the gradient vector. |
| // Thus, we want the projection of the current position vector |
| // onto the gradient vector, then normalized with respect to the |
| // length of the gradient vector, giving a value which can be mapped |
| // into the range 0-1. |
| // projection = |
| // currentVector dot gradientVector / length(gradientVector) |
| // normalized = projection / length(gradientVector) |
| |
| float startx = (float)start.getX(); |
| float starty = (float)start.getY(); |
| float endx = (float)end.getX(); |
| float endy = (float)end.getY(); |
| |
| float dx = endx - startx; // change in x from start to end |
| float dy = endy - starty; // change in y from start to end |
| float dSq = dx*dx + dy*dy; // total distance squared |
| |
| // avoid repeated calculations by doing these divides once |
| float constX = dx/dSq; |
| float constY = dy/dSq; |
| |
| // incremental change along gradient for +x |
| dgdX = a00*constX + a10*constY; |
| // incremental change along gradient for +y |
| dgdY = a01*constX + a11*constY; |
| |
| // constant, incorporates the translation components from the matrix |
| gc = (a02-startx)*constX + (a12-starty)*constY; |
| } |
| |
| /** |
| * Return a Raster containing the colors generated for the graphics |
| * operation. This is where the area is filled with colors distributed |
| * linearly. |
| * |
| * @param x,y,w,h the area in device space for which colors are |
| * generated. |
| */ |
| protected void fillRaster(int[] pixels, int off, int adjust, |
| int x, int y, int w, int h) |
| { |
| // current value for row gradients |
| float g = 0; |
| |
| // used to end iteration on rows |
| int rowLimit = off + w; |
| |
| // constant which can be pulled out of the inner loop |
| float initConst = (dgdX*x) + gc; |
| |
| for (int i = 0; i < h; i++) { // for every row |
| |
| // initialize current value to be start |
| g = initConst + dgdY*(y+i); |
| |
| while (off < rowLimit) { // for every pixel in this row |
| // get the color |
| pixels[off++] = indexIntoGradientsArrays(g); |
| |
| // incremental change in g |
| g += dgdX; |
| } |
| |
| // change in off from row to row |
| off += adjust; |
| |
| //rowlimit is width + offset |
| rowLimit = off + w; |
| } |
| } |
| } |