1/* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#include <math.h> 18#include "filters.h" 19 20unsigned char clamp(int c) 21{ 22 int N = 255; 23 c &= ~(c >> 31); 24 c -= N; 25 c &= (c >> 31); 26 c += N; 27 return (unsigned char) c; 28} 29 30void JNIFUNCF(ImageFilterContrast, nativeApplyFilter, jobject bitmap, jint width, jint height, jfloat bright) 31{ 32 char* destination = 0; 33 AndroidBitmap_lockPixels(env, bitmap, (void**) &destination); 34 unsigned char * rgb = (unsigned char * )destination; 35 int i; 36 int len = width * height * 4; 37 float m = (float)pow(2, bright/100.); 38 float c = 127-m*127; 39 40 for (i = 0; i < len; i+=4) { 41 rgb[RED] = clamp((int)(m*rgb[RED]+c)); 42 rgb[GREEN] = clamp((int)(m*rgb[GREEN]+c)); 43 rgb[BLUE] = clamp((int)(m*rgb[BLUE]+c)); 44 } 45 AndroidBitmap_unlockPixels(env, bitmap); 46} 47 48