1 files changed, 76 insertions, 0 deletions
diff --git a/samples/png.cc b/samples/png.cc
new file mode 100644
index 0000000..79c6983
--- /dev/null
+++ b/samples/png.cc
@@ -0,0 +1,76 @@
+// Copyright 2019 The Amber Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "samples/png.h"
+
+#include <cassert>
+
+#include "amber/result.h"
+#include "amber/value.h"
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wweak-vtables"
+#include "third_party/lodepng/lodepng.h"
+#pragma clang diagnostic pop
+
+namespace png {
+
+namespace {
+
+unsigned char byte0(uint32_t word) {
+  return static_cast<unsigned char>(word);
+}
+
+unsigned char byte1(uint32_t word) {
+  return static_cast<unsigned char>(word >> 8);
+}
+
+unsigned char byte2(uint32_t word) {
+  return static_cast<unsigned char>(word >> 16);
+}
+
+unsigned char byte3(uint32_t word) {
+  return static_cast<unsigned char>(word >> 24);
+}
+
+}  // namespace
+
+std::pair<amber::Result, std::string> ConvertToPNG(
+    uint32_t width,
+    uint32_t height,
+    const std::vector<amber::Value>& values) {
+  assert(values.size() == width * height);
+
+  std::vector<unsigned char> data;
+
+  // Prepare data as lodepng expects it
+  for (amber::Value value : values) {
+    const uint32_t pixel = value.AsUint32();
+    data.push_back(byte2(pixel));  // R
+    data.push_back(byte1(pixel));  // G
+    data.push_back(byte0(pixel));  // B
+    data.push_back(byte3(pixel));  // A
+  }
+
+  std::vector<unsigned char> png;
+  unsigned error = lodepng::encode(png, data, width, height);
+  if (error) {
+    return std::make_pair(amber::Result("lodepng::encode() returned non-zero"),
+                          nullptr);
+  }
+
+  return std::make_pair(amber::Result(), std::string(png.begin(), png.end()));
+}
+
+}  // namespace png