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
clamp(int c)20 unsigned 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
JNIFUNCF(ImageFilterContrast,nativeApplyFilter,jobject bitmap,jint width,jint height,jfloat bright)30 void 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