BasisImageConverter: Replace image loading sources with empty stubs

modules/FindBasisUniversal.cmake

@@ -174,24 +174,19 @@ foreach(_component ${BasisUniversal_FIND_COMPONENTS})
                     ${BasisUniversalEncoder_DIR}/basisu_resampler.cpp
                     ${BasisUniversalEncoder_DIR}/basisu_resample_filters.cpp
                     ${BasisUniversalEncoder_DIR}/basisu_ssim.cpp
-                    ${BasisUniversalEncoder_DIR}/basisu_uastc_enc.cpp
-                    ${BasisUniversalEncoder_DIR}/jpgd.cpp)
+                    ${BasisUniversalEncoder_DIR}/basisu_uastc_enc.cpp)
 
                 # Files not present in all supported basis versions, treat them
                 # as optional and do nothing if not found.
                 foreach(_file
                     # Removed in 1.16
-                    apg_bmp.c
                     basisu_astc_decomp.cpp
                     basisu_global_selector_palette_helpers.cpp
-                    lodepng.cpp
                     # Added in 1.16
                     basisu_opencl.cpp
-                    pvpngreader.cpp
                     # Added in 1.50
                     basisu_astc_hdr_enc.cpp
-                    3rdparty/android_astc_decomp.cpp
-                    3rdparty/tinyexr.cpp)
+                    3rdparty/android_astc_decomp.cpp)
                     # Disable the find root path here, it overrides the
                     # CMAKE_FIND_ROOT_PATH_MODE_INCLUDE setting potentially set in
                     # toolchains.
@@ -204,6 +199,10 @@ foreach(_component ${BasisUniversal_FIND_COMPONENTS})
                     endif()
                 endforeach()
 
+                # Source files for image file loading are not added here.
+                # BasisImageConverter provides stubs for all used functions.
+                # See src/external/basis-image-loading-stubs for more info.
+
                 foreach(_file ${BasisUniversalEncoder_SOURCES})
                     _basis_setup_source_file(${_file})
                 endforeach()

src/MagnumPlugins/BasisImageConverter/CMakeLists.txt

@@ -64,6 +64,10 @@ target_include_directories(BasisImageConverter PUBLIC
     # Turns #include "../zstd/zstd.h" into an actual external zstd.h include.
     # See the README in that directory for details.
     ${PROJECT_SOURCE_DIR}/src/external/basis-zstd-include-uncrapifier/put-this-on-include-path)
+# Adds empty definitions for unused image loading library functions.
+# See the README in that directory for details.
+target_sources(BasisImageConverter PRIVATE
+    ${PROJECT_SOURCE_DIR}/src/external/basis-image-loading-stubs/stubs.cpp)
 target_link_libraries(BasisImageConverter
     PUBLIC Magnum::Trade
     PRIVATE BasisUniversal::Encoder)

src/external/basis-image-loading-stubs/README.md

@@ -0,0 +1,14 @@
+The Basis encoder unconditionally includes code for loading image files from
+disk (.png, .exr, etc.), but BasisImageConverter always supplies image data
+in memory. So the code path using the disk loading is never run, wasting size
+and increasing compile time needlessly.
+
+There's no way to remove it through a preprocessor define so instead all
+required functions are provided as empty stubs in stubs.cpp.
+
+The following library sources are stubbed:
+jpgd.cpp
+apg_bmp.c // Removed in 1.16
+lodepng.cpp // Removed in 1.16
+pvpngreader.cpp // Added in 1.16
+3rdparty/tinyexr.cpp // Added in 1.50

src/external/basis-image-loading-stubs/stubs.cpp

@@ -0,0 +1,122 @@
+#include <Corrade/Utility/Assert.h>
+
+#include <vector>
+#include <string>
+
+/* jpgd, present in all supported versions */
+
+namespace jpgd {
+
+unsigned char* decompress_jpeg_image_from_file(const char*, int*, int*, int*, int, uint32_t) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+}
+
+/* apg_bmp, removed in 1.16 */
+
+extern "C" {
+
+unsigned char* apg_bmp_read(const char*, int*, int*, unsigned int*) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+void apg_bmp_free(unsigned char*) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+}
+
+/* lodepng, removed in 1.16 */
+
+/* Can't forward-declare since it has no explicit underlying type */
+typedef enum LodePNGColorType {
+  LCT_GREY = 0,
+  LCT_RGB = 2,
+  LCT_PALETTE = 3,
+  LCT_GREY_ALPHA = 4,
+  LCT_RGBA = 6
+} LodePNGColorType;
+
+typedef struct LodePNGState LodePNGState;
+
+namespace lodepng {
+
+class State {
+public:
+    State();
+    virtual ~State();
+};
+
+State::State() {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+State::~State() {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+unsigned decode(std::vector<unsigned char>&, unsigned&, unsigned&, const unsigned char*, size_t, LodePNGColorType, unsigned) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+unsigned encode(std::vector<unsigned char>&, const unsigned char*, unsigned, unsigned, LodePNGColorType, unsigned) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+unsigned load_file(std::vector<unsigned char>&, const std::string&) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+unsigned save_file(const std::vector<unsigned char>&, const std::string&) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+}
+
+unsigned lodepng_inspect(unsigned*, unsigned*, LodePNGState*, const unsigned char*, size_t) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+/* pvpng, added in 1.16 */
+
+namespace pv_png {
+
+void* load_png(const void*, size_t, uint32_t, uint32_t&, uint32_t&, uint32_t&) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+}
+
+/* tinyexr, added in 1.50 */
+
+extern "C" {
+
+int LoadEXRWithLayer(float **, int*, int*, const char*, const char*, const char**, int*) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+typedef struct TEXRHeader EXRHeader;
+typedef struct TEXRImage EXRImage;
+
+void InitEXRHeader(EXRHeader*) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+void InitEXRImage(EXRImage*) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+void FreeEXRErrorMessage(const char*) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+int SaveEXRImageToFile(const EXRImage*, const EXRHeader*, const char*, const char**) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+int LoadEXRFromMemory(float**, int*, int*, const unsigned char*, size_t, const char**) {
+    CORRADE_INTERNAL_ASSERT_UNREACHABLE();
+}
+
+}