From 265790659c5bdfd8ef28be3bcb6b57e68c35b522 Mon Sep 17 00:00:00 2001
From: Jan De Dobbeleer <jan.de.dobbeleer@gmail.com>
Date: Wed, 8 Jun 2022 20:02:30 +0200
Subject: [PATCH] fix(font): install correctly on Windows

---
 src/font/install_windows.go | 62 ++++++++++++++++++++++++-------------
 1 file changed, 41 insertions(+), 21 deletions(-)

diff --git a/src/font/install_windows.go b/src/font/install_windows.go
index 81efb6d9..330d2dad 100644
--- a/src/font/install_windows.go
+++ b/src/font/install_windows.go
@@ -1,34 +1,37 @@
-// Derived from https://github.com/Crosse/font-install
-// Copyright 2020 Seth Wright <seth@crosse.org>
 package font
 
 import (
+	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
-	"path"
+	"path/filepath"
+	"syscall"
+	"unsafe"
 
 	"golang.org/x/sys/windows/registry"
 )
 
-// FontsDir denotes the path to the user's fonts directory on Linux.
-// Windows doesn't have the concept of a permanent, per-user collection
-// of fonts, meaning that all fonts are stored in the system-level fonts
-// directory, which is %WINDIR%\Fonts by default.
-var FontsDir = path.Join(os.Getenv("WINDIR"), "Fonts")
+// https://docs.microsoft.com/en-us/windows/win32/api/wingdi/nf-wingdi-addfontresourcea
+var FontsDir = filepath.Join(os.Getenv("WINDIR"), "Fonts")
+
+const (
+	WM_FONTCHANGE  = 0x001D // nolint:revive
+	HWND_BROADCAST = 0xFFFF // nolint:revive
+)
 
 func install(font *Font) (err error) {
 	// To install a font on Windows:
 	//  - Copy the file to the fonts directory
-	//  - Create a registry entry for the font
-	fullPath := path.Join(FontsDir, font.FileName)
-
-	err = ioutil.WriteFile(fullPath, font.Data, 0644) //nolint:gosec
+	//  - Add registry entry
+	//  - Call AddFontResourceW to set the font
+	// -  Notify other applications that the fonts have changed
+	fullPath := filepath.Join(FontsDir, font.FileName)
+	err = os.WriteFile(fullPath, font.Data, 0644)
 	if err != nil {
-		return err
+		return
 	}
 
-	// Second, write metadata about the font to the registry.
+	// Add registry entry
 	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts`, registry.WRITE)
 	if err != nil {
 		// If this fails, remove the font file as well.
@@ -40,12 +43,8 @@ func install(font *Font) (err error) {
 	}
 	defer k.Close()
 
-	// Apparently it's "ok" to mark an OpenType font as "TrueType",
-	// and since this tool only supports True- and OpenType fonts,
-	// this should be Okay(tm).
-	// Besides, Windows does it, so why can't I?
-	valueName := fmt.Sprintf("%v (TrueType)", font.FileName)
-	if err = k.SetStringValue(font.Name, valueName); err != nil {
+	name := fmt.Sprintf("%v (TrueType)", font.Name)
+	if err = k.SetStringValue(name, font.FileName); err != nil {
 		// If this fails, remove the font file as well.
 		if nexterr := os.Remove(fullPath); nexterr != nil {
 			return nexterr
@@ -54,5 +53,26 @@ func install(font *Font) (err error) {
 		return err
 	}
 
+	gdi32 := syscall.NewLazyDLL("gdi32.dll")
+	proc := gdi32.NewProc("AddFontResourceW")
+
+	fontPtr, err := syscall.UTF16PtrFromString(fullPath)
+	if err != nil {
+		return
+	}
+
+	ret, _, _ := proc.Call(uintptr(unsafe.Pointer(fontPtr)))
+	if ret == 0 {
+		return errors.New("unable to add font resource")
+	}
+
+	// Notify other applications that the fonts have changed
+	user32 := syscall.NewLazyDLL("user32.dll")
+	procSendMessageW := user32.NewProc("SendMessageW")
+	_, _, e1 := syscall.SyscallN(procSendMessageW.Addr(), uintptr(HWND_BROADCAST), uintptr(WM_FONTCHANGE), 0, 0)
+	if e1 != 0 {
+		return errors.New("unable to broadcast font change")
+	}
+
 	return nil
 }