Add a custom stream IO implementation for Freetype

Freetype expects its IO to perform like mmap (i.e. seeking to be free),
but the non-unix implementation uses fseek and fread. This
implementation simply reads the entire file into a buffer, as fonts
generally aren't very big.

Cuts the time to recreate the fontconfig cache on my machine by about
60%.

build/freetype2/freetype.vcxproj

@@ -36,6 +36,7 @@
     <InstallHeader Include="$(Freetype2SrcDir)\include\**\*.h" />
   </ItemGroup>
   <ItemGroup>
+    <ClCompile Include="$(MSBuildThisFileDirectory)ftsystem.cpp" />
     <ClCompile Include="$(Freetype2SrcDir)\src\autofit\autofit.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftbase.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftbbox.c" />
@@ -52,7 +53,6 @@
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftpfr.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftstroke.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftsynth.c" />
-    <ClCompile Include="$(Freetype2SrcDir)\src\base\ftsystem.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\fttype1.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftwinfnt.c" />
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftxf86.c" />

build/freetype2/freetype.vcxproj.filters

@@ -62,7 +62,7 @@
     <ClCompile Include="$(Freetype2SrcDir)\src\base\ftsynth.c">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="$(Freetype2SrcDir)\src\base\ftsystem.c">
+    <ClCompile Include="$(MSBuildThisFileDirectory)ftsystem.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
     <ClCompile Include="$(Freetype2SrcDir)\src\base\fttype1.c">

build/freetype2/ftsystem.cpp

@@ -0,0 +1,75 @@
+// Copyright (c) 2014, Thomas Goyne <plorkyeran@aegisub.org>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+// Aegisub Project http://www.aegisub.org/
+
+// The non-unix version of ftsystem.c uses stdio functions, but freetype uses
+// streams as if they had mmap's performance characteristics (as it uses mmap
+// on unix), which results in mind-blowingly poor performance (35%+ of the
+// fontconfig caching runtime is spent on fseek).
+
+#include <ft2build.h>
+#include FT_INTERNAL_DEBUG_H
+#include FT_INTERNAL_STREAM_H
+#include FT_SYSTEM_H
+#include FT_ERRORS_H
+
+#include <codecvt>
+#include <fstream>
+
+extern "C" FT_Error FT_Stream_Open(FT_Stream stream, const char *filepathname) {
+	if (!stream)
+		return FT_THROW(Invalid_Stream_Handle);
+
+	stream->descriptor.pointer = nullptr;
+	stream->pathname.pointer = const_cast<char *>(filepathname);
+	stream->base = nullptr;
+	stream->pos = 0;
+	stream->read = nullptr;
+	stream->close = nullptr;
+
+	std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t> converter;
+	std::ifstream file(converter.from_bytes(filepathname), std::ios::binary);
+	if (!file.good())
+		return FT_THROW(Cannot_Open_Resource);
+
+	file.seekg(0, std::ios::end);
+	stream->size = (unsigned long)file.tellg();
+	if (!stream->size)
+		return FT_THROW(Cannot_Open_Stream);
+	file.seekg(0, std::ios::beg);
+
+	stream->base = (unsigned char *)malloc(stream->size);
+	file.read((char *)stream->base, stream->size);
+
+	stream->close = [](FT_Stream stream) {
+		free(stream->base);
+		stream->size = 0;
+		stream->base = nullptr;
+	};
+
+	return FT_Err_Ok;
+}
+
+extern "C" FT_Memory FT_New_Memory() {
+	return new FT_MemoryRec_{
+		nullptr,
+		[](FT_Memory, long size) { return malloc(size); },
+		[](FT_Memory, void *ptr) { free(ptr); },
+		[](FT_Memory, long, long size, void *ptr) { return realloc(ptr, size); }};
+}
+
+extern "C" void FT_Done_Memory(FT_Memory memory) {
+	delete memory;
+}