win32 gui: replace D2D renderer with D3d11 shader

src/win32/FontFace.zig

@@ -0,0 +1,31 @@
+const FontFace = @This();
+
+const std = @import("std");
+
+// it seems that Windows only supports font faces with up to 31 characters
+pub const max = 31;
+
+buf: [max + 1]u16,
+len: u5,
+
+pub fn initUtf8(utf8: []const u8) error{ TooLong, InvalidUtf8 }!FontFace {
+    const utf16_len = std.unicode.calcUtf16LeLen(utf8) catch return error.InvalidUtf8;
+    if (utf16_len > max)
+        return error.TooLong;
+    var result: FontFace = .{ .buf = undefined, .len = @intCast(utf16_len) };
+    result.buf[utf16_len] = 0;
+    const actual_len = try std.unicode.utf8ToUtf16Le(&result.buf, utf8);
+    std.debug.assert(actual_len == utf16_len);
+    return result;
+}
+
+pub fn ptr(self: *const FontFace) [*:0]const u16 {
+    std.debug.assert(self.buf[@as(usize, self.len)] == 0);
+    return @ptrCast(&self.buf);
+}
+pub fn slice(self: *const FontFace) [:0]const u16 {
+    return self.ptr()[0..self.len :0];
+}
+pub fn eql(self: *const FontFace, other: *const FontFace) bool {
+    return std.mem.eql(u16, self.slice(), other.slice());
+}