glfw: Add loading DLL

internal/glfw/load_windows.go

@@ -0,0 +1,80 @@
+// Copyright 2018 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package glfw
+
+import (
+	"bytes"
+	"compress/gzip"
+	"io"
+	"io/ioutil"
+	"os"
+
+	"golang.org/x/sys/windows"
+)
+
+type dll struct {
+	d    *windows.LazyDLL
+	path string
+}
+
+func createTempDLL(content io.Reader) (string, error) {
+	f, err := ioutil.TempFile("", "glfw.*.dll")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	fn := f.Name()
+
+	if _, err := io.Copy(f, content); err != nil {
+		return "", err
+	}
+
+	return fn, nil
+}
+
+func loadDLL() (*dll, error) {
+	f, err := gzip.NewReader(bytes.NewReader(glfwDLLCompressed))
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	fn, err := createTempDLL(f)
+	if err != nil {
+		return nil, err
+	}
+
+	return &dll{
+		d:    windows.NewLazyDLL(fn),
+		path: fn,
+	}, nil
+}
+
+func (d *dll) unload() error {
+	if err := windows.FreeLibrary(windows.Handle(d.d.Handle())); err != nil {
+		return err
+	}
+	if err := os.Remove(d.path); err != nil {
+		return err
+	}
+	return nil
+}
+
+func init() {
+	if _, err := loadDLL(); err != nil {
+		panic(err)
+	}
+}