font/freetype: Enable bitmap glyphs for non-color faces

src/font/face/freetype.zig

@@ -288,7 +288,6 @@ pub const Face = struct {
         self.face.loadGlyph(glyph_id, .{
             .render = true,
             .color = self.face.hasColor(),
-            .no_bitmap = !self.face.hasColor(),
         }) catch return false;
 
         // If the glyph is SVG we assume colorized
@@ -323,14 +322,6 @@ pub const Face = struct {
             // glyph properties before render so we don't render here.
             .render = !self.synthetic.bold,
 
-            // Disable bitmap strikes for now since it causes issues with
-            // our cell metrics and rasterization. In the future, this is
-            // all fixable so we can enable it.
-            //
-            // This must be enabled for color faces though because those are
-            // often colored bitmaps, which we support.
-            .no_bitmap = !self.face.hasColor(),
-
             // use options from config
             .no_hinting = !self.load_flags.hinting,
             .force_autohint = !self.load_flags.@"force-autohint",

src/font/face/freetype_convert.zig

@@ -43,26 +43,14 @@ pub fn monoToGrayscale(alloc: Allocator, bm: Bitmap) Allocator.Error!Bitmap {
     var buf = try alloc.alloc(u8, bm.width * bm.rows);
     errdefer alloc.free(buf);
 
-    // width divided by 8 because each byte has 8 pixels. This is therefore
-    // the number of bytes in each row.
-    const bytes_per_row = bm.width >> 3;
-
-    var source_i: usize = 0;
-    var target_i: usize = 0;
-    var i: usize = bm.rows;
-    while (i > 0) : (i -= 1) {
-        var j: usize = bytes_per_row;
-        while (j > 0) : (j -= 1) {
-            var bit: u4 = 8;
-            while (bit > 0) : (bit -= 1) {
-                const mask = @as(u8, 1) << @as(u3, @intCast(bit - 1));
-                const bitval: u8 = if (bm.buffer[source_i + (j - 1)] & mask > 0) 0xFF else 0;
-                buf[target_i] = bitval;
-                target_i += 1;
-            }
+    for (0..bm.rows) |y| {
+        const row_offset = y * @as(usize, @intCast(bm.pitch));
+        for (0..bm.width) |x| {
+            const byte_offset = row_offset + @divTrunc(x, 8);
+            const mask = @as(u8, 1) << @intCast(7 - (x % 8));
+            const bit: u8 = @intFromBool((bm.buffer[byte_offset] & mask) != 0);
+            buf[y * bm.width + x] = bit * 255;
         }
-
-        source_i += @intCast(bm.pitch);
     }
 
     var copy = bm;