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 "filters.h"
18 #include <math.h>
19
20 #ifdef __cplusplus
21 extern "C" {
22 #endif
23
24
25 #define PI_F 3.141592653589f
26
27 class ImageRGBA {
28 public:
ImageRGBA(unsigned char * image,int width,int height)29 ImageRGBA(unsigned char* image, int width, int height)
30 : image_(image), width_(width), height_(height) {
31 width_step_ = width * 4;
32 }
33
Width() const34 int Width() const {
35 return width_;
36 }
37
Height() const38 int Height() const {
39 return height_;
40 }
41
42 // Pixel accessor.
operator ()(int x,int y)43 unsigned char* operator()(int x, int y) {
44 return image_ + y * width_step_ + x * 4;
45 }
operator ()(int x,int y) const46 const unsigned char* operator()(int x, int y) const {
47 return image_ + y * width_step_ + x * 4;
48 }
49
50 private:
51 unsigned char* image_;
52 int width_;
53 int height_;
54 int width_step_;
55 };
56
57 // Interpolate a pixel in a 3 channel image.
InterpolatePixel(const ImageRGBA & image,float x,float y,unsigned char * dest)58 inline void InterpolatePixel(const ImageRGBA &image, float x, float y,
59 unsigned char* dest) {
60 // Get pointers and scale factors for the source pixels.
61 float ax = x - floor(x);
62 float ay = y - floor(y);
63 float axn = 1.0f - ax;
64 float ayn = 1.0f - ay;
65 const unsigned char *p = image(x, y);
66 const unsigned char *p2 = image(x, y + 1);
67
68 // Interpolate each image color plane.
69 dest[0] = static_cast<unsigned char>(axn * ayn * p[0] + ax * ayn * p[4] +
70 ax * ay * p2[4] + axn * ay * p2[0] + 0.5f);
71 p++;
72 p2++;
73
74 dest[1] = static_cast<unsigned char>(axn * ayn * p[0] + ax * ayn * p[4] +
75 ax * ay * p2[4] + axn * ay * p2[0] + 0.5f);
76 p++;
77 p2++;
78
79 dest[2] = static_cast<unsigned char>(axn * ayn * p[0] + ax * ayn * p[4] +
80 ax * ay * p2[4] + axn * ay * p2[0] + 0.5f);
81 p++;
82 p2++;
83 dest[3] = 0xFF;
84 }
85
86 // Wrap circular coordinates around the globe
wrap(float value,float dimension)87 inline float wrap(float value, float dimension) {
88 return value - (dimension * floor(value/dimension));
89 }
90
StereographicProjection(float scale,float angle,unsigned char * input_image,int input_width,int input_height,unsigned char * output_image,int output_width,int output_height)91 void StereographicProjection(float scale, float angle, unsigned char* input_image,
92 int input_width, int input_height,
93 unsigned char* output_image, int output_width,
94 int output_height) {
95 ImageRGBA input(input_image, input_width, input_height);
96 ImageRGBA output(output_image, output_width, output_height);
97
98 const float image_scale = output_width * scale;
99
100 for (int x = 0; x < output_width; x++) {
101 // Center and scale x
102 float xf = (x - output_width / 2.0f) / image_scale;
103
104 for (int y = 0; y < output_height; y++) {
105 // Center and scale y
106 float yf = (y - output_height / 2.0f) / image_scale;
107
108 // Convert to polar
109 float r = hypotf(xf, yf);
110 float theta = angle+atan2(yf, xf);
111 if (theta>PI_F) theta-=2*PI_F;
112
113 // Project onto plane
114 float phi = 2 * atan(1 / r);
115 // (theta stays the same)
116
117 // Map to panorama image
118 float px = (theta / (2 * PI_F)) * input_width;
119 float py = (phi / PI_F) * input_height;
120
121 // Wrap around the globe
122 px = wrap(px, input_width);
123 py = wrap(py, input_height);
124
125 // Write the interpolated pixel
126 InterpolatePixel(input, px, py, output(x, y));
127 }
128 }
129 }
130
131
JNIFUNCF(ImageFilterTinyPlanet,nativeApplyFilter,jobject bitmap_in,jint width,jint height,jobject bitmap_out,jint output_size,jfloat scale,jfloat angle)132 void JNIFUNCF(ImageFilterTinyPlanet, nativeApplyFilter, jobject bitmap_in, jint width, jint height, jobject bitmap_out, jint output_size, jfloat scale,jfloat angle)
133 {
134 char* source = 0;
135 char* destination = 0;
136 AndroidBitmap_lockPixels(env, bitmap_in, (void**) &source);
137 AndroidBitmap_lockPixels(env, bitmap_out, (void**) &destination);
138 unsigned char * rgb_in = (unsigned char * )source;
139 unsigned char * rgb_out = (unsigned char * )destination;
140
141 StereographicProjection(scale,angle, rgb_in, width, height, rgb_out, output_size, output_size);
142 AndroidBitmap_unlockPixels(env, bitmap_in);
143 AndroidBitmap_unlockPixels(env, bitmap_out);
144 }
145
146 #ifdef __cplusplus
147 }
148 #endif
149
150
151