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 <jni.h>
18#include <math.h>
19#include <android/bitmap.h>
20
21#ifdef __cplusplus
22extern "C" {
23#endif
24
25
26#define PI_F 3.141592653589f
27
28class ImageRGBA {
29 public:
30  ImageRGBA(unsigned char* image, int width, int height)
31   : image_(image), width_(width), height_(height) {
32    width_step_ = width * 4;
33  }
34
35  int Width() const {
36    return width_;
37  }
38
39  int Height() const {
40    return height_;
41  }
42
43  // Pixel accessor.
44  unsigned char* operator()(int x, int y) {
45    return image_ + y * width_step_ + x * 4;
46  }
47  const unsigned char* operator()(int x, int y) const {
48    return image_ + y * width_step_ + x * 4;
49  }
50
51 private:
52  unsigned char* image_;
53  int width_;
54  int height_;
55  int width_step_;
56};
57
58// Interpolate a pixel in a 3 channel image.
59inline void InterpolatePixel(const ImageRGBA &image, float x, float y,
60                             unsigned char* dest) {
61  // Get pointers and scale factors for the source pixels.
62  float ax = x - floor(x);
63  float ay = y - floor(y);
64  float axn = 1.0f - ax;
65  float ayn = 1.0f - ay;
66  const unsigned char *p = image(x, y);
67  const unsigned char *p2 = image(x, y + 1);
68
69  // Interpolate each image color plane.
70  dest[0] = static_cast<unsigned char>(axn * ayn * p[0] + ax * ayn * p[4] +
71             ax * ay * p2[4] + axn * ay * p2[0] + 0.5f);
72  p++;
73  p2++;
74
75  dest[1] = static_cast<unsigned char>(axn * ayn * p[0] + ax * ayn * p[4] +
76             ax * ay * p2[4] + axn * ay * p2[0] + 0.5f);
77  p++;
78  p2++;
79
80  dest[2] = static_cast<unsigned char>(axn * ayn * p[0] + ax * ayn * p[4] +
81             ax * ay * p2[4] + axn * ay * p2[0] + 0.5f);
82  p++;
83  p2++;
84  dest[3] = 0xFF;
85}
86
87// Wrap circular coordinates around the globe
88inline float wrap(float value, float dimension) {
89  return value - (dimension * floor(value/dimension));
90}
91
92void StereographicProjection(float scale, float angle, unsigned char* input_image,
93                             int input_width, int input_height,
94                             unsigned char* output_image, int output_width,
95                             int output_height) {
96  ImageRGBA input(input_image, input_width, input_height);
97  ImageRGBA output(output_image, output_width, output_height);
98
99  const float image_scale = output_width * scale;
100
101  for (int x = 0; x < output_width; x++) {
102    // Center and scale x
103    float xf = (x - output_width / 2.0f) / image_scale;
104
105    for (int y = 0; y < output_height; y++) {
106      // Center and scale y
107      float yf = (y - output_height / 2.0f) / image_scale;
108
109      // Convert to polar
110      float r = hypotf(xf, yf);
111      float theta = angle+atan2(yf, xf);
112      if (theta>PI_F) theta-=2*PI_F;
113
114      // Project onto plane
115      float phi = 2 * atan(1 / r);
116      // (theta stays the same)
117
118      // Map to panorama image
119      float px = (theta / (2 * PI_F)) * input_width;
120      float py = (phi / PI_F) * input_height;
121
122      // Wrap around the globe
123      px = wrap(px, input_width);
124      py = wrap(py, input_height);
125
126      // Write the interpolated pixel
127      InterpolatePixel(input, px, py, output(x, y));
128    }
129  }
130}
131
132
133JNIEXPORT void JNICALL Java_com_android_camera_tinyplanet_TinyPlanetNative_process(JNIEnv* env, jobject obj, jobject bitmap_in, jint width, jint height, jobject bitmap_out, jint output_size, jfloat scale, jfloat angle)
134{
135    char* source = 0;
136    char* destination = 0;
137    AndroidBitmap_lockPixels(env, bitmap_in, (void**) &source);
138    AndroidBitmap_lockPixels(env, bitmap_out, (void**) &destination);
139    unsigned char * rgb_in = (unsigned char * )source;
140    unsigned char * rgb_out = (unsigned char * )destination;
141
142    StereographicProjection(scale, angle, rgb_in, width, height, rgb_out, output_size, output_size);
143    AndroidBitmap_unlockPixels(env, bitmap_in);
144    AndroidBitmap_unlockPixels(env, bitmap_out);
145}
146
147#ifdef __cplusplus
148}
149#endif
150
151
152