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/ppm.h"
16
17#include <cassert>
18
19#include "amber/result.h"
20#include "amber/value.h"
21
22namespace ppm {
23namespace {
24
25const uint32_t kMaximumColorValue = 255;
26
27uint8_t byte0(uint32_t word) {
28  return static_cast<uint8_t>(word & 0xff);
29}
30
31uint8_t byte1(uint32_t word) {
32  return static_cast<uint8_t>((word >> 8) & 0xff);
33}
34
35uint8_t byte2(uint32_t word) {
36  return static_cast<uint8_t>((word >> 16) & 0xff);
37}
38
39}  // namespace
40
41amber::Result ConvertToPPM(uint32_t width,
42                           uint32_t height,
43                           const std::vector<amber::Value>& values,
44                           std::vector<uint8_t>* buffer) {
45  assert(values.size() == (width * height) &&
46         "Buffer values != width * height");
47  assert(!values.empty() && "Buffer empty");
48
49  // Write PPM header
50  std::string image = "P6\n";
51  image += std::to_string(width) + " " + std::to_string(height) + "\n";
52  image += std::to_string(kMaximumColorValue) + "\n";
53
54  for (char ch : image)
55    buffer->push_back(static_cast<uint8_t>(ch));
56
57  // Write PPM data
58  for (amber::Value value : values) {
59    const uint32_t pixel = value.AsUint32();
60    // We assume B8G8R8A8_UNORM here:
61    buffer->push_back(byte2(pixel));  // R
62    buffer->push_back(byte1(pixel));  // G
63    buffer->push_back(byte0(pixel));  // B
64    // PPM does not support alpha channel
65  }
66
67  return {};
68}
69
70}  // namespace ppm
71