Optional PNG support (#596)

As discussed in #591, this CL sets lodepng as an optional library.

5 files changed, 29 insertions, 4 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 92d8184..aa09507 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,6 +41,8 @@ option(AMBER_SKIP_SHADERC
   "Skip building Shaderc into the library" ${AMBER_SKIP_SHADERC})
 option(AMBER_SKIP_SAMPLES
   "Skip building sample application" ${AMBER_SKIP_SAMPLES})
+option(AMBER_SKIP_LODEPNG
+  "Skip building lodepng into the library" ${AMBER_SKIP_LODEPNG})
 option(AMBER_USE_DXC "Enable DXC integration" ${AMBER_USE_DXC})
 option(AMBER_USE_LOCAL_VULKAN "Build with vulkan in third_party" OFF)
 option(AMBER_USE_CLSPV "Build with Clspv support" OFF)
@@ -80,6 +82,12 @@ else()
   set(AMBER_ENABLE_SAMPLES TRUE)
 endif()
 
+if (${AMBER_SKIP_LODEPNG})
+  set(AMBER_ENABLE_LODEPNG FALSE)
+else()
+  set(AMBER_ENABLE_LODEPNG TRUE)
+endif()
+
 if (${AMBER_ENABLE_SWIFTSHADER})
   # Swiftshader requires the loader to be built.
   set(AMBER_USE_LOCAL_VULKAN TRUE)
@@ -106,6 +114,7 @@ message(STATUS "Amber enable SPIRV-Tools: ${AMBER_ENABLE_SPIRV_TOOLS}")
 message(STATUS "Amber enable Shaderc: ${AMBER_ENABLE_SHADERC}")
 message(STATUS "Amber enable tests: ${AMBER_ENABLE_TESTS}")
 message(STATUS "Amber enable samples: ${AMBER_ENABLE_SAMPLES}")
+message(STATUS "Amber enable lodepng: ${AMBER_ENABLE_LODEPNG}")
 message(STATUS "Amber enable SwiftShader: ${AMBER_ENABLE_SWIFTSHADER}")
 message(STATUS "Amber enable DXC: ${AMBER_ENABLE_DXC}")
 message(STATUS "Amber enable Clspv: ${AMBER_ENABLE_CLSPV}")
@@ -130,6 +139,7 @@ add_definitions(-DAMBER_ENABLE_SPIRV_TOOLS=$<BOOL:${AMBER_ENABLE_SPIRV_TOOLS}>)
 add_definitions(-DAMBER_ENABLE_SHADERC=$<BOOL:${AMBER_ENABLE_SHADERC}>)
 add_definitions(-DAMBER_ENABLE_DXC=$<BOOL:${AMBER_ENABLE_DXC}>)
 add_definitions(-DAMBER_ENABLE_CLSPV=$<BOOL:${AMBER_ENABLE_CLSPV}>)
+add_definitions(-DAMBER_ENABLE_LODEPNG=$<BOOL:${AMBER_ENABLE_LODEPNG}>)
 
 set(CMAKE_DEBUG_POSTFIX "")
 
diff --git a/README.md b/README.md
index efb1363..db70b6e 100644
--- a/README.md
+++ b/README.md
@@ -196,6 +196,9 @@ out/Debug/amber tests/cases/clear.vkscript
 The sample app returns a value of 0 on success or non-zero on error. Any issues
 encountered should be displayed on the console.
 
+By default, `out/Debug/amber` supports saving the output image into '.png'
+file. You can disable this by passing `-DAMBER_SKIP_LODEPNG=true` to cmake.
+
 ## Contributing
 
 Please see the [CONTRIBUTING](CONTRIBUTING.md) and
diff --git a/samples/CMakeLists.txt b/samples/CMakeLists.txt
index 3831b8b..d41ee21 100644
--- a/samples/CMakeLists.txt
+++ b/samples/CMakeLists.txt
@@ -19,12 +19,16 @@ set(AMBER_SOURCES
     config_helper.cc
     log.cc
     ppm.cc
-    png.cc
     timestamp.cc
     ${CMAKE_BINARY_DIR}/src/build-versions.h.fake
 )
 
-set(AMBER_EXTRA_LIBS "lodepng")
+set(AMBER_EXTRA_LIBS "")
+
+if (${AMBER_ENABLE_LODEPNG})
+  set(AMBER_SOURCES ${AMBER_SOURCES} png.cc)
+  list(APPEND AMBER_EXTRA_LIBS "lodepng")
+endif()
 
 if (${Vulkan_FOUND})
   set(AMBER_SOURCES ${AMBER_SOURCES} config_helper_vulkan.cc)
@@ -45,6 +49,7 @@ endif()
 
 add_executable(amber ${AMBER_SOURCES})
 target_include_directories(amber PRIVATE "${CMAKE_BINARY_DIR}")
+
 set_target_properties(amber PROPERTIES OUTPUT_NAME "amber")
 target_link_libraries(amber libamber ${AMBER_EXTRA_LIBS})
 amber_default_compile_options(amber)
diff --git a/samples/amber.cc b/samples/amber.cc
index 0f68a9f..8c945b1 100644
--- a/samples/amber.cc
+++ b/samples/amber.cc
@@ -25,12 +25,15 @@
 
 #include "amber/recipe.h"
 #include "samples/config_helper.h"
-#include "samples/png.h"
 #include "samples/ppm.h"
 #include "samples/timestamp.h"
 #include "src/build-versions.h"
 #include "src/make_unique.h"
 
+#if AMBER_ENABLE_LODEPNG
+#include "samples/png.h"
+#endif  // AMBER_ENABLE_LODEPNG
+
 namespace {
 
 const char* kGeneratedColorBuffer = "framebuffer";
@@ -431,8 +434,12 @@ int main(int argc, const char** argv) {
       for (const amber::BufferInfo& buffer_info : amber_options.extractions) {
         if (buffer_info.buffer_name == options.fb_name) {
           if (usePNG) {
+#if AMBER_ENABLE_LODEPNG
             result = png::ConvertToPNG(buffer_info.width, buffer_info.height,
                                        buffer_info.values, &out_buf);
+#else   // AMBER_ENABLE_LODEPNG
+            result = amber::Result("PNG support not enabled");
+#endif  // AMBER_ENABLE_LODEPNG
           } else {
             ppm::ConvertToPPM(buffer_info.width, buffer_info.height,
                               buffer_info.values, &out_buf);
diff --git a/third_party/CMakeLists.txt b/third_party/CMakeLists.txt
index f23cdb0..db865ad 100644
--- a/third_party/CMakeLists.txt
+++ b/third_party/CMakeLists.txt
@@ -41,7 +41,7 @@ if (${AMBER_ENABLE_SHADERC})
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/shaderc)
 endif()
 
-if (${AMBER_ENABLE_SAMPLES})
+if (${AMBER_ENABLE_SAMPLES} AND ${AMBER_ENABLE_LODEPNG})
   # Lodepng
   set(LODEPNG_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/lodepng/lodepng.cpp)
   add_library(lodepng STATIC ${LODEPNG_SOURCES})