dep/stb: Use zlib for png compression

dep/stb/CMakeLists.txt

@@ -10,4 +10,4 @@ set(SRCS
 add_library(stb ${SRCS})
 target_include_directories(stb PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/include" "${CMAKE_CURRENT_SOURCE_DIR}/src")
 target_include_directories(stb INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}/include")
-target_link_libraries(stb Threads::Threads "${CMAKE_DL_LIBS}")
+target_link_libraries(stb zlib Threads::Threads "${CMAKE_DL_LIBS}")

dep/stb/src/stb_image_write.c

@@ -1,2 +1,28 @@
+#include <stdlib.h>
+
+#include "zlib.h"
+
+// https://github.com/nothings/stb/issues/113
+static unsigned char* compress_for_stbiw(unsigned char* data, int data_len, int* out_len, int quality)
+{
+  const uLongf bufSize = compressBound(data_len);
+
+  // note that buf will be free'd by stb_image_write.h
+  // with STBIW_FREE() (plain free() by default)
+  unsigned char* buf = malloc(bufSize);
+  if (buf == NULL)
+    return NULL;
+
+  if (compress2(buf, &bufSize, data, data_len, quality) != Z_OK)
+  {
+    free(buf);
+    return NULL;
+  }
+
+  *out_len = bufSize;
+  return buf;
+}
+
+#define STBIW_ZLIB_COMPRESS compress_for_stbiw
 #define STB_IMAGE_WRITE_IMPLEMENTATION
 #include "stb_image_write.h"

dep/stb/stb.vcxproj

@@ -22,7 +22,7 @@
   <ItemDefinitionGroup>
     <ClCompile>
       <WarningLevel>TurnOffAllWarnings</WarningLevel>
-      <AdditionalIncludeDirectories>$(ProjectDir)include;$(ProjectDir)src;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>$(SolutionDir)dep\zlib\include;$(ProjectDir)include;$(ProjectDir)src;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
     </ClCompile>
   </ItemDefinitionGroup>