src/font: working on initiaizing deferred fonts from fc

pkg/freetype/Library.zig

@@ -32,6 +32,18 @@ pub fn version(self: Library) Version {
     return v;
 }
 
+/// Call FT_New_Face to open a font from a file.
+pub fn initFace(self: Library, path: [:0]const u8, index: i32) Error!Face {
+    var face: Face = undefined;
+    try intToError(c.FT_New_Face(
+        self.handle,
+        path.ptr,
+        index,
+        &face.handle,
+    ));
+    return face;
+}
+
 /// Call FT_Open_Face to open a font that has been loaded into memory.
 pub fn initMemoryFace(self: Library, data: []const u8, index: i32) Error!Face {
     var face: Face = undefined;

src/font/DeferredFace.zig

@@ -61,6 +61,31 @@ pub inline fn loaded(self: DeferredFace) bool {
     return self.face != null;
 }
 
+pub fn load(self: *DeferredFace) !void {
+    // No-op if we already loaded
+    if (self.face != null) return;
+
+    if (options.fontconfig) {
+        try self.loadFontconfig();
+        return;
+    }
+
+    unreachable;
+}
+
+fn loadFontconfig(self: *DeferredFace) !void {
+    assert(self.face == null);
+    const fc = self.fc.?;
+
+    // Filename and index for our face so we can load it
+    const filename = (try fc.pattern.get(.file, 0)).string;
+    const face_index = (try fc.pattern.get(.index, 0)).integer;
+
+    self.face = try Face.initFile(filename, face_index, .{
+        .points = fc.req_size,
+    });
+}
+
 /// Returns true if this face can satisfy the given codepoint and
 /// presentation. If presentation is null, then it just checks if the
 /// codepoint is present at all.

src/font/Face.zig

@@ -50,6 +50,23 @@ pub const DesiredSize = struct {
     }
 };
 
+/// Initialize a new font face with the given source in-memory.
+pub fn initFile(lib: Library, path: [:0]const u8, index: i32, size: DesiredSize) !Face {
+    const face = try lib.lib.initFace(path, index);
+    errdefer face.deinit();
+    try face.selectCharmap(.unicode);
+    try setSize_(face, size);
+
+    const hb_font = try harfbuzz.freetype.createFont(face.handle);
+    errdefer hb_font.destroy();
+
+    return Face{
+        .face = face,
+        .hb_font = hb_font,
+        .presentation = if (face.hasColor()) .emoji else .text,
+    };
+}
+
 /// Initialize a new font face with the given source in-memory.
 pub fn init(lib: Library, source: [:0]const u8, size: DesiredSize) !Face {
     const face = try lib.lib.initMemoryFace(source, 0);