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