1// Copyright 2019 The Amber Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#include "samples/png.h"
16
17#include <cassert>
18
19#include "amber/result.h"
20#include "amber/value.h"
21
22#pragma clang diagnostic push
23#pragma clang diagnostic ignored "-Wweak-vtables"
24#include "third_party/lodepng/lodepng.h"
25#pragma clang diagnostic pop
26
27namespace png {
28
29namespace {
30
31unsigned char byte0(uint32_t word) {
32  return static_cast<unsigned char>(word);
33}
34
35unsigned char byte1(uint32_t word) {
36  return static_cast<unsigned char>(word >> 8);
37}
38
39unsigned char byte2(uint32_t word) {
40  return static_cast<unsigned char>(word >> 16);
41}
42
43unsigned char byte3(uint32_t word) {
44  return static_cast<unsigned char>(word >> 24);
45}
46
47}  // namespace
48
49amber::Result ConvertToPNG(uint32_t width,
50                           uint32_t height,
51                           const std::vector<amber::Value>& values,
52                           std::vector<uint8_t>* buffer) {
53  assert(values.size() == (width * height) &&
54         "Buffer values != width * height");
55  assert(!values.empty() && "Buffer empty");
56
57  std::vector<uint8_t> data;
58
59  // Prepare data as lodepng expects it
60  for (const amber::Value& value : values) {
61    const uint32_t pixel = value.AsUint32();
62    data.push_back(byte2(pixel));  // R
63    data.push_back(byte1(pixel));  // G
64    data.push_back(byte0(pixel));  // B
65    data.push_back(byte3(pixel));  // A
66  }
67
68  lodepng::State state;
69
70  // Force RGBA color type, otherwise many PNG decoders will ignore the alpha
71  // channel.
72  state.encoder.auto_convert = 0;
73  state.info_raw.colortype = LodePNGColorType::LCT_RGBA;
74  state.info_raw.bitdepth = 8;
75  state.info_png.color.colortype = LodePNGColorType::LCT_RGBA;
76  state.info_png.color.bitdepth = 8;
77
78  if (lodepng::encode(*buffer, data, width, height, state) != 0)
79    return amber::Result("lodepng::encode() returned non-zero");
80
81  return {};
82}
83
84amber::Result LoadPNG(const std::string file_name,
85                      uint32_t* width,
86                      uint32_t* height,
87                      std::vector<amber::Value>* values) {
88  std::vector<uint8_t> decoded_buffer;
89  if (lodepng::decode(decoded_buffer, *width, *height, file_name,
90                      LodePNGColorType::LCT_RGBA, 8) != 0) {
91    return amber::Result("lodepng::decode() returned non-zero");
92  }
93
94  for (auto d : decoded_buffer) {
95    amber::Value v;
96    v.SetIntValue(d);
97    values->push_back(v);
98  }
99
100  return {};
101}
102
103}  // namespace png
104