Java example source code file (PiscesTileGenerator.java)

This example Java source code file (PiscesTileGenerator.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

aatilegenerator, concurrenthashmap, piscescache, piscestilegenerator, runtimeexception, string, threading, threads, tile_size, tile_size\*tile_size\*maxalpha, util

The PiscesTileGenerator.java Java example source code

/*
 * Copyright (c) 2007, 2011, 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 sun.java2d.pisces;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import sun.java2d.pipe.AATileGenerator;

final class PiscesTileGenerator implements AATileGenerator {
    public static final int TILE_SIZE = PiscesCache.TILE_SIZE;

    // perhaps we should be using weak references here, but right now
    // that's not necessary. The way the renderer is, this map will
    // never contain more than one element - the one with key 64, since
    // we only do 8x8 supersampling.
    private static final Map<Integer, byte[]> alphaMapsCache = new
                   ConcurrentHashMap<Integer, byte[]>();

    PiscesCache cache;
    int x, y;
    final int maxalpha;
    private final int maxTileAlphaSum;

    // The alpha map used by this object (taken out of our map cache) to convert
    // pixel coverage counts gotten from PiscesCache (which are in the range
    // [0, maxalpha]) into alpha values, which are in [0,256).
    byte alphaMap[];

    public PiscesTileGenerator(Renderer r, int maxalpha) {
        this.cache = r.getCache();
        this.x = cache.bboxX0;
        this.y = cache.bboxY0;
        this.alphaMap = getAlphaMap(maxalpha);
        this.maxalpha = maxalpha;
        this.maxTileAlphaSum = TILE_SIZE*TILE_SIZE*maxalpha;
    }

    private static byte[] buildAlphaMap(int maxalpha) {
        byte[] alMap = new byte[maxalpha+1];
        int halfmaxalpha = maxalpha>>2;
        for (int i = 0; i <= maxalpha; i++) {
            alMap[i] = (byte) ((i * 255 + halfmaxalpha) / maxalpha);
        }
        return alMap;
    }

    public static byte[] getAlphaMap(int maxalpha) {
        if (!alphaMapsCache.containsKey(maxalpha)) {
            alphaMapsCache.put(maxalpha, buildAlphaMap(maxalpha));
        }
        return alphaMapsCache.get(maxalpha);
    }

    public void getBbox(int bbox[]) {
        bbox[0] = cache.bboxX0;
        bbox[1] = cache.bboxY0;
        bbox[2] = cache.bboxX1;
        bbox[3] = cache.bboxY1;
        //System.out.println("bbox["+bbox[0]+", "+bbox[1]+" => "+bbox[2]+", "+bbox[3]+"]");
    }

    /**
     * Gets the width of the tiles that the generator batches output into.
     * @return the width of the standard alpha tile
     */
    public int getTileWidth() {
        return TILE_SIZE;
    }

    /**
     * Gets the height of the tiles that the generator batches output into.
     * @return the height of the standard alpha tile
     */
    public int getTileHeight() {
        return TILE_SIZE;
    }

    /**
     * Gets the typical alpha value that will characterize the current
     * tile.
     * The answer may be 0x00 to indicate that the current tile has
     * no coverage in any of its pixels, or it may be 0xff to indicate
     * that the current tile is completely covered by the path, or any
     * other value to indicate non-trivial coverage cases.
     * @return 0x00 for no coverage, 0xff for total coverage, or any other
     *         value for partial coverage of the tile
     */
    public int getTypicalAlpha() {
        int al = cache.alphaSumInTile(x, y);
        // Note: if we have a filled rectangle that doesn't end on a tile
        // border, we could still return 0xff, even though al!=maxTileAlphaSum
        // This is because if we return 0xff, our users will fill a rectangle
        // starting at x,y that has width = Math.min(TILE_SIZE, bboxX1-x),
        // and height min(TILE_SIZE,bboxY1-y), which is what should happen.
        // However, to support this, we would have to use 2 Math.min's
        // and 2 multiplications per tile, instead of just 2 multiplications
        // to compute maxTileAlphaSum. The savings offered would probably
        // not be worth it, considering how rare this case is.
        // Note: I have not tested this, so in the future if it is determined
        // that it is worth it, it should be implemented. Perhaps this method's
        // interface should be changed to take arguments the width and height
        // of the current tile. This would eliminate the 2 Math.min calls that
        // would be needed here, since our caller needs to compute these 2
        // values anyway.
        return (al == 0x00 ? 0x00 :
            (al == maxTileAlphaSum ? 0xff : 0x80));
    }

    /**
     * Skips the current tile and moves on to the next tile.
     * Either this method, or the getAlpha() method should be called
     * once per tile, but not both.
     */
    public void nextTile() {
        if ((x += TILE_SIZE) >= cache.bboxX1) {
            x = cache.bboxX0;
            y += TILE_SIZE;
        }
    }

    /**
     * Gets the alpha coverage values for the current tile.
     * Either this method, or the nextTile() method should be called
     * once per tile, but not both.
     */
    public void getAlpha(byte tile[], int offset, int rowstride) {
        // Decode run-length encoded alpha mask data
        // The data for row j begins at cache.rowOffsetsRLE[j]
        // and is encoded as a set of 2-byte pairs (val, runLen)
        // terminated by a (0, 0) pair.

        int x0 = this.x;
        int x1 = x0 + TILE_SIZE;
        int y0 = this.y;
        int y1 = y0 + TILE_SIZE;
        if (x1 > cache.bboxX1) x1 = cache.bboxX1;
        if (y1 > cache.bboxY1) y1 = cache.bboxY1;
        y0 -= cache.bboxY0;
        y1 -= cache.bboxY0;

        int idx = offset;
        for (int cy = y0; cy < y1; cy++) {
            int[] row = cache.rowAARLE[cy];
            assert row != null;
            int cx = cache.minTouched(cy);
            if (cx > x1) cx = x1;

            for (int i = x0; i < cx; i++) {
                tile[idx++] = 0x00;
            }

            int pos = 2;
            while (cx < x1 && pos < row[1]) {
                byte val;
                int runLen = 0;
                assert row[1] > 2;
                try {
                    val = alphaMap[row[pos]];
                    runLen = row[pos + 1];
                    assert runLen > 0;
                } catch (RuntimeException e0) {
                    System.out.println("maxalpha = "+maxalpha);
                    System.out.println("tile["+x0+", "+y0+
                                       " => "+x1+", "+y1+"]");
                    System.out.println("cx = "+cx+", cy = "+cy);
                    System.out.println("idx = "+idx+", pos = "+pos);
                    System.out.println("len = "+runLen);
                    System.out.print(cache.toString());
                    e0.printStackTrace();
                    throw e0;
                }

                int rx0 = cx;
                cx += runLen;
                int rx1 = cx;
                if (rx0 < x0) rx0 = x0;
                if (rx1 > x1) rx1 = x1;
                runLen = rx1 - rx0;
                //System.out.println("M["+runLen+"]");
                while (--runLen >= 0) {
                    try {
                        tile[idx++] = val;
                    } catch (RuntimeException e) {
                        System.out.println("maxalpha = "+maxalpha);
                        System.out.println("tile["+x0+", "+y0+
                                           " => "+x1+", "+y1+"]");
                        System.out.println("cx = "+cx+", cy = "+cy);
                        System.out.println("idx = "+idx+", pos = "+pos);
                        System.out.println("rx0 = "+rx0+", rx1 = "+rx1);
                        System.out.println("len = "+runLen);
                        System.out.print(cache.toString());
                        e.printStackTrace();
                        throw e;
                    }
                }
                pos += 2;
            }
            if (cx < x0) { cx = x0; }
            while (cx < x1) {
                tile[idx++] = 0x00;
                cx++;
            }
            /*
            for (int i = idx - (x1-x0); i < idx; i++) {
                System.out.print(hex(tile[i], 2));
            }
            System.out.println();
            */
            idx += (rowstride - (x1-x0));
        }
        nextTile();
    }

    static String hex(int v, int d) {
        String s = Integer.toHexString(v);
        while (s.length() < d) {
            s = "0"+s;
        }
        return s.substring(0, d);
    }

    /**
     * Disposes this tile generator.
     * No further calls will be made on this instance.
     */
    public void dispose() {}
}