Add a basic CoreText-based fonts collector backend

src/Makefile

@@ -59,7 +59,6 @@ src_OBJ := \
 	$(d)export_framerate.o \
 	$(d)fft.o \
 	$(d)font_file_lister.o \
-	$(d)font_file_lister_fontconfig.o \
 	$(d)frame_main.o \
 	$(d)gl_text.o \
 	$(d)gl_wrap.o \
@@ -119,7 +118,10 @@ src_OBJ := \
 	$(TOP)lib/libuniversalchardet.a \
 
 ifeq (yes, $(BUILD_DARWIN))
+src_OBJ += $(d)font_file_lister_coretext.o
 src_OBJ += $(subst .mm,.o,$(wildcard $(d)osx/*.mm))
+else
+src_OBJ += $(d)font_file_lister_fontconfig.o
 endif
 
 ###############

src/font_file_lister.h

@@ -63,7 +63,25 @@ public:
 };
 
 using FontFileLister = GdiFontFileLister;
+
+#elif defined(__APPLE__)
+
+struct CoreTextFontFileLister {
+	CoreTextFontFileLister(FontCollectorStatusCallback &) {}
+
+	/// @brief Get the path to the font with the given styles
+	/// @param facename Name of font face
+	/// @param bold ASS font weight
+	/// @param italic Italic?
+	/// @param characters Characters in this style
+	/// @return Path to the matching font file(s), or empty if not found
+	CollectionResult GetFontPaths(std::string const& facename, int bold, bool italic, std::vector<int> const& characters);
+};
+
+using FontFileLister = CoreTextFontFileLister;
+
 #else
+
 typedef struct _FcConfig FcConfig;
 typedef struct _FcFontSet FcFontSet;
 

src/font_file_lister_coretext.mm

@@ -0,0 +1,94 @@
+// Copyright (c) 2016, 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/
+
+#include "font_file_lister.h"
+
+#include <AppKit/AppKit.h>
+#include <CoreText/CoreText.h>
+
+namespace {
+void process_font(CollectionResult& ret, NSFontDescriptor *font, int bold, bool italic,
+                  std::vector<int> const& characters) {
+	// For whatever reason there is no NSFontURLAttribute
+	NSURL *url = [font objectForKey:(__bridge NSString *)kCTFontURLAttribute];
+	if (!url)
+		return;
+
+	NSDictionary *attributes = [font objectForKey:NSFontTraitsAttribute];
+	double weight = [attributes[NSFontWeightTrait] doubleValue];
+	double slant = [attributes[NSFontSlantTrait] doubleValue];
+
+	if (italic != (slant > 0.03))
+		return;
+	if (bold == 0 && weight > 0)
+		return;
+	if (bold == 1 && weight < 0.4)
+		return;
+
+	NSCharacterSet *codepoints = [font objectForKey:NSFontCharacterSetAttribute];
+	for (int chr : characters) {
+		if (![codepoints longCharacterIsMember:chr]) {
+			ret.missing += chr;
+		}
+	}
+
+	ret.paths.push_back(url.absoluteString.UTF8String);
+}
+}
+
+CollectionResult CoreTextFontFileLister::GetFontPaths(std::string const& facename,
+                                                      int bold, bool italic,
+                                                      std::vector<int> const& characters) {
+	CollectionResult ret;
+
+	@autoreleasepool {
+		NSString *name = @(facename.c_str() + (facename[0] == '@'));
+		NSArray *attrs = @[
+			[NSFontDescriptor fontDescriptorWithFontAttributes:@{NSFontFamilyAttribute: name}],
+			[NSFontDescriptor fontDescriptorWithFontAttributes:@{NSFontFaceAttribute: name}],
+			[NSFontDescriptor fontDescriptorWithFontAttributes:@{NSFontNameAttribute: name}]
+		];
+
+		auto font_collection = [NSFontCollection fontCollectionWithDescriptors:attrs];
+		for (NSFontDescriptor *desc in font_collection.matchingDescriptors) {
+			process_font(ret, desc, bold, italic, characters);
+
+			// If we didn't get any results, check for non-bold/italic variants
+			// and collect them with a warning
+			if (ret.paths.empty() && bold) {
+				process_font(ret, desc, 0, italic, characters);
+				if (!ret.paths.empty())
+					ret.fake_bold = true;
+			}
+
+			if (ret.paths.empty() && italic) {
+				process_font(ret, desc, bold, false, characters);
+				if (!ret.paths.empty())
+					ret.fake_italic = true;
+			}
+
+			if (ret.paths.empty() && bold && italic) {
+				process_font(ret, desc, 0, false, characters);
+				if (!ret.paths.empty()) {
+					ret.fake_bold = true;
+					ret.fake_italic = true;
+				}
+			}
+		}
+	}
+
+	return ret;
+}