| J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-1998 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | /* |
| 27 | * This file defines some of the standard utility macros and definitions |
| 28 | * used throughout the image conversion package header files. |
| 29 | */ |
| 30 | |
| 31 | #include "img_globals.h" |
| 32 | |
| 33 | #define ALPHASHIFT 24 |
| 34 | #define REDSHIFT 16 |
| 35 | #define GREENSHIFT 8 |
| 36 | #define BLUESHIFT 0 |
| 37 | |
| 38 | /* |
| 39 | * The following mapping is used between coordinates when scaling an |
| 40 | * image: |
| 41 | * |
| 42 | * srcXY = floor(((dstXY + .5) * srcWH) / dstWH) |
| 43 | * = floor((dstXY * srcWH + .5 * srcWH) / dstWH) |
| 44 | * = floor((2 * dstXY * srcWH + srcWH) / (2 * dstWH)) |
| 45 | * |
| 46 | * Since the numerator can always be assumed to be non-negative for |
| 47 | * all values of dstXY >= 0 and srcWH,dstWH >= 1, then the floor |
| 48 | * function can be calculated using the standard C integer division |
| 49 | * operator. |
| 50 | * |
| 51 | * To calculate back from a source range of pixels to the destination |
| 52 | * range of pixels that they will affect, we need to find a srcXY |
| 53 | * that satisfies the following inequality based upon the above mapping |
| 54 | * function: |
| 55 | * |
| 56 | * srcXY <= (2 * dstXY * srcWH + srcWH) / (2 * dstWH) < (srcXY+1) |
| 57 | * 2 * srcXY * dstWH <= 2 * dstXY * srcWH + srcWH < 2 * (srcXY+1) * dstWH |
| 58 | * |
| 59 | * To calculate the lowest dstXY that satisfies these constraints, we use |
| 60 | * the first half of the inequality: |
| 61 | * |
| 62 | * 2 * dstXY * srcWH + srcWH >= 2 * srcXY * dstWH |
| 63 | * 2 * dstXY * srcWH >= 2 * srcXY * dstWH - srcWH |
| 64 | * dstXY >= (2 * srcXY * dstWH - srcWH) / (2 * srcWH) |
| 65 | * dstXY = ceil((2 * srcXY * dstWH - srcWH) / (2 * srcWH)) |
| 66 | * dstXY = floor((2 * srcXY * dstWH - srcWH + 2*srcWH - 1) / (2 * srcWH)) |
| 67 | * dstXY = floor((2 * srcXY * dstWH + srcWH - 1) / (2 * srcWH)) |
| 68 | * |
| 69 | * Since the numerator can be shown to be non-negative, we can calculate |
| 70 | * this with the standard C integer division operator. |
| 71 | * |
| 72 | * To calculate the highest dstXY that satisfies these constraints, we use |
| 73 | * the second half of the inequality: |
| 74 | * |
| 75 | * 2 * dstXY * srcWH + srcWH < 2 * (srcXY+1) * dstWH |
| 76 | * 2 * dstXY * srcWH < 2 * (srcXY+1) * dstWH - srcWH |
| 77 | * dstXY < (2 * (srcXY+1) * dstWH - srcWH) / (2 * srcWH) |
| 78 | * dstXY = ceil((2 * (srcXY+1) * dstWH - srcWH) / (2 * srcWH)) - 1 |
| 79 | * dstXY = floor((2 * (srcXY+1) * dstWH - srcWH + 2 * srcWH - 1) |
| 80 | * / (2 * srcWH)) - 1 |
| 81 | * dstXY = floor((2 * (srcXY+1) * dstWH + srcWH - 1) / (2 * srcWH)) - 1 |
| 82 | * |
| 83 | * Again, the numerator is always non-negative so we can use integer division. |
| 84 | */ |
| 85 | |
| 86 | #define SRC_XY(dstXY, srcWH, dstWH) \ |
| 87 | (((2 * (dstXY) * (srcWH)) + (srcWH)) / (2 * (dstWH))) |
| 88 | |
| 89 | #define DEST_XY_RANGE_START(srcXY, srcWH, dstWH) \ |
| 90 | (((2 * (srcXY) * (dstWH)) + (srcWH) - 1) / (2 * (srcWH))) |
| 91 | |
| 92 | #define DEST_XY_RANGE_END(srcXY, srcWH, dstWH) \ |
| 93 | (((2 * ((srcXY) + 1) * (dstWH)) + (srcWH) - 1) / (2 * (srcWH)) - 1) |
| 94 | |
| 95 | /* |
| 96 | * This union is a utility structure for manipulating pixel pointers |
| 97 | * of variable depths. |
| 98 | */ |
| 99 | typedef union { |
| 100 | void *vp; |
| 101 | unsigned char *bp; |
| 102 | unsigned short *sp; |
| 103 | unsigned int *ip; |
| 104 | } pixptr; |
| 105 | |
| 106 | #define RGBTOGRAY(r, g, b) ((int) (.299 * r + .587 * g + .114 * b)) |
| 107 | |
| 108 | #define ComponentBound(c) \ |
| 109 | (((c) < 0) ? 0 : (((c) > 255) ? 255 : (c))) |
| 110 | |
| 111 | #define paddedwidth(number, boundary) \ |
| 112 | (((number) + ((boundary) - 1)) & (~((boundary) - 1))) |