Add image export to farbfeld format

samples/Android.mk

@@ -21,6 +21,7 @@ LOCAL_SRC_FILES:= \
     amber.cc \
     config_helper.cc \
     config_helper_vulkan.cc \
+    farbfeld.cc \
     log.cc \
     ppm.cc
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/.. $(LOCAL_PATH)/../include

samples/CMakeLists.txt

@@ -17,6 +17,7 @@ include_directories("${PROJECT_SOURCE_DIR}/include")
 set(AMBER_SOURCES
     amber.cc
     config_helper.cc
+    farbfeld.cc
     log.cc
     ppm.cc
     ${CMAKE_BINARY_DIR}/src/build-versions.h.fake

samples/amber.cc

@@ -23,6 +23,7 @@
 #include "amber/amber.h"
 #include "amber/recipe.h"
 #include "samples/config_helper.h"
+#include "samples/farbfeld.h"
 #include "samples/ppm.h"
 #include "src/build-versions.h"
 #include "src/make_unique.h"
@@ -53,7 +54,7 @@ const char kUsage[] = R"(Usage: amber [options] SCRIPT [SCRIPTS...]
   -s                  -- Print summary of pass/failure.
   -d                  -- Disable validation layers.
   -t <spirv_env> -- The target SPIR-V environment. Defaults to SPV_ENV_UNIVERSAL_1_0.
-  -i <filename>       -- Write rendering to <filename> as a PPM image.
+  -i <filename>       -- Write rendering to <filename>, as a farbfeld image if filename ends with '.ff', as a PPM image otherwise.
   -b <filename>       -- Write contents of a UBO or SSBO to <filename>.
   -B <buffer>         -- Index of buffer to write. Defaults buffer 0.
   -e <engine>         -- Specify graphics engine: vulkan, dawn. Default is vulkan.
@@ -324,8 +325,17 @@ int main(int argc, const char** argv) {
       std::string image;
       for (amber::BufferInfo buffer_info : amber_options.extractions) {
         if (buffer_info.buffer_name == "framebuffer") {
-          std::tie(result, image) = ppm::ConvertToPPM(
-              buffer_info.width, buffer_info.height, buffer_info.values);
+          // Image encoding: use farbfeld if image filename ends with ".ff",
+          // otherwise default to PPM.
+          if (options.image_filename.compare(
+                  options.image_filename.length() - 4,
+                  options.image_filename.length(), ".ff")) {
+            std::tie(result, image) = farbfeld::ConvertToFarbfeld(
+                buffer_info.width, buffer_info.height, buffer_info.values);
+          } else {
+            std::tie(result, image) = ppm::ConvertToPPM(
+                buffer_info.width, buffer_info.height, buffer_info.values);
+          }
           break;
         }
       }

samples/farbfeld.cc

@@ -0,0 +1,83 @@
+// 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/farbfeld.h"
+
+#include <cassert>
+
+#include "amber/result.h"
+#include "amber/value.h"
+
+namespace farbfeld {
+
+namespace {
+
+char byte0(uint32_t word) {
+  return static_cast<char>(word);
+}
+
+char byte1(uint32_t word) {
+  return static_cast<char>(word >> 8);
+}
+
+char byte2(uint32_t word) {
+  return static_cast<char>(word >> 16);
+}
+
+char byte3(uint32_t word) {
+  return static_cast<char>(word >> 24);
+}
+
+}  // namespace
+
+std::pair<amber::Result, std::string> ConvertToFarbfeld(
+    uint32_t width,
+    uint32_t height,
+    const std::vector<amber::Value>& values) {
+  assert(values.size() == width * height);
+
+  // Farbfeld format details: https://tools.suckless.org/farbfeld/
+
+  // Farbfeld header
+  std::string image = "farbfeld";
+  // 32 bits big endian unsigned integers for width, and then height
+  image.push_back(byte3(width));
+  image.push_back(byte2(width));
+  image.push_back(byte1(width));
+  image.push_back(byte0(width));
+  image.push_back(byte3(height));
+  image.push_back(byte2(height));
+  image.push_back(byte1(height));
+  image.push_back(byte0(height));
+
+  // Farbfeld data
+  for (amber::Value value : values) {
+    const uint32_t pixel = value.AsUint32();
+    // We assume R8G8B8A8_UINT here. Note the zero char is added to fill up the
+    // 16 bits available for each channel.
+    const char zero = static_cast<char>(0);
+    image.push_back(byte0(pixel));  // R
+    image.push_back(zero);
+    image.push_back(byte1(pixel));  // G
+    image.push_back(zero);
+    image.push_back(byte2(pixel));  // B
+    image.push_back(zero);
+    image.push_back(byte3(pixel));  // A
+    image.push_back(zero);
+  }
+
+  return std::make_pair(amber::Result(), image);
+}
+
+}  // namespace farbfeld

samples/farbfeld.h

@@ -0,0 +1,36 @@
+// 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.
+
+#ifndef SAMPLES_FARBFELD_H_
+#define SAMPLES_FARBFELD_H_
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "amber/amber.h"
+
+namespace farbfeld {
+
+/// Converts the image of dimensions |width| and |height| and with pixels stored
+/// in row-major order in |values| with format R8G8B8A8 into farbfeld format,
+/// returning the farbfeld binary as a string.
+std::pair<amber::Result, std::string> ConvertToFarbfeld(
+    uint32_t width,
+    uint32_t height,
+    const std::vector<amber::Value>& values);
+
+}  // namespace farbfeld
+
+#endif  // SAMPLES_FARBFELD_H__