001/* 002Copyright 2006 Jerry Huxtable 003 004Licensed under the Apache License, Version 2.0 (the "License"); 005you may not use this file except in compliance with the License. 006You may obtain a copy of the License at 007 008 http://www.apache.org/licenses/LICENSE-2.0 009 010Unless required by applicable law or agreed to in writing, software 011distributed under the License is distributed on an "AS IS" BASIS, 012WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013See the License for the specific language governing permissions and 014limitations under the License. 015*/ 016 017package com.jhlabs.composite; 018 019import java.awt.*; 020import java.awt.image.*; 021 022public final class OverlayComposite extends RGBComposite { 023 024 public OverlayComposite( float alpha ) { 025 super( alpha ); 026 } 027 028 public CompositeContext createContext( ColorModel srcColorModel, ColorModel dstColorModel, RenderingHints hints ) { 029 return new Context( extraAlpha, srcColorModel, dstColorModel ); 030 } 031 032 static class Context extends RGBCompositeContext { 033 public Context( float alpha, ColorModel srcColorModel, ColorModel dstColorModel ) { 034 super( alpha, srcColorModel, dstColorModel ); 035 } 036 037 public void composeRGB( int[] src, int[] dst, float alpha ) { 038 int w = src.length; 039 040 for ( int i = 0; i < w; i += 4 ) { 041 int sr = src[i]; 042 int dir = dst[i]; 043 int sg = src[i+1]; 044 int dig = dst[i+1]; 045 int sb = src[i+2]; 046 int dib = dst[i+2]; 047 int sa = src[i+3]; 048 int dia = dst[i+3]; 049 int dor, dog, dob; 050 051 int t; 052 if ( dir < 128 ) { 053 t = dir * sr + 0x80; 054 dor = 2 * (((t >> 8) + t) >> 8); 055 } else { 056 t = (255-dir) * (255-sr) + 0x80; 057 dor = 2 * (255 - ( ((t >> 8) + t) >> 8 )); 058 } 059 if ( dig < 128 ) { 060 t = dig * sg + 0x80; 061 dog = 2 * (((t >> 8) + t) >> 8); 062 } else { 063 t = (255-dig) * (255-sg) + 0x80; 064 dog = 2 * (255 - ( ((t >> 8) + t) >> 8 )); 065 } 066 if ( dib < 128 ) { 067 t = dib * sb + 0x80; 068 dob = 2 * (((t >> 8) + t) >> 8); 069 } else { 070 t = (255-dib) * (255-sb) + 0x80; 071 dob = 2 * (255 - ( ((t >> 8) + t) >> 8 )); 072 } 073 074 float a = alpha*sa/255f; 075 float ac = 1-a; 076 077 dst[i] = (int)(a*dor + ac*dir); 078 dst[i+1] = (int)(a*dog + ac*dig); 079 dst[i+2] = (int)(a*dob + ac*dib); 080 dst[i+3] = (int)(sa*alpha + dia*ac); 081 } 082 } 083 } 084 085}