gl: download ANGLE if necessary
For golang/go#9306
Change-Id: Ibb469d843d2bddeaa3690c59bc9ad532ea3473f7
Reviewed-on: https://go-review.googlesource.com/17810
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
diff --git a/gl/dll_windows.go b/gl/dll_windows.go
new file mode 100644
index 0000000..50e6257
--- /dev/null
+++ b/gl/dll_windows.go
@@ -0,0 +1,163 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gl
+
+import (
+ "archive/tar"
+ "compress/gzip"
+ "fmt"
+ "io"
+ "io/ioutil"
+ "log"
+ "net/http"
+ "os"
+ "path/filepath"
+ "runtime"
+)
+
+var debug = log.New(ioutil.Discard, "gl: ", log.LstdFlags)
+
+func downloadDLLs() (path string, err error) {
+ url := "https://dl.google.com/go/mobile/angle-dd5c5b-" + runtime.GOARCH + ".tgz"
+ debug.Printf("downloading %s", url)
+ resp, err := http.Get(url)
+ if err != nil {
+ return "", fmt.Errorf("gl: %v", err)
+ }
+ defer func() {
+ err2 := resp.Body.Close()
+ if err == nil && err2 != nil {
+ err = fmt.Errorf("gl: error reading body from %v: %v", url, err2)
+ }
+ }()
+ if resp.StatusCode != http.StatusOK {
+ err := fmt.Errorf("gl: error fetching %v, status: %v", url, resp.Status)
+ return "", err
+ }
+
+ r, err := gzip.NewReader(resp.Body)
+ if err != nil {
+ return "", fmt.Errorf("gl: error reading gzip from %v: %v", url, err)
+ }
+ tr := tar.NewReader(r)
+ var bytesGLESv2, bytesEGL []byte
+ for {
+ header, err := tr.Next()
+ if err == io.EOF {
+ break
+ }
+ if err != nil {
+ return "", fmt.Errorf("gl: error reading tar from %v: %v", url, err)
+ }
+ switch header.Name {
+ case "angle-" + runtime.GOARCH + "/libglesv2.dll":
+ bytesGLESv2, err = ioutil.ReadAll(tr)
+ case "angle-" + runtime.GOARCH + "/libegl.dll":
+ bytesEGL, err = ioutil.ReadAll(tr)
+ default: // skip
+ }
+ if err != nil {
+ return "", fmt.Errorf("gl: error reading %v from %v: %v", header.Name, url, err)
+ }
+ }
+ if len(bytesGLESv2) == 0 || len(bytesEGL) == 0 {
+ return "", fmt.Errorf("gl: did not find both DLLs in %v", url)
+ }
+
+ writeDLLs := func(path string) error {
+ if err := ioutil.WriteFile(filepath.Join(path, "libglesv2.dll"), bytesGLESv2, 0755); err != nil {
+ return fmt.Errorf("gl: cannot install ANGLE: %v", err)
+ }
+ if err := ioutil.WriteFile(filepath.Join(path, "libegl.dll"), bytesEGL, 0755); err != nil {
+ return fmt.Errorf("gl: cannot install ANGLE: %v", err)
+ }
+ return nil
+ }
+
+ // First, we attempt to install these DLLs in LOCALAPPDATA/Shiny.
+ //
+ // Traditionally we would use the system32 directory, but it is
+ // no longer writable by normal programs.
+ os.MkdirAll(appdataPath(), 0775)
+ if err := writeDLLs(appdataPath()); err == nil {
+ return appdataPath(), nil
+ }
+ debug.Printf("DLLs could not be written to %s", appdataPath())
+
+ // Second, install in GOPATH/pkg if it exists.
+ gopath := os.Getenv("GOPATH")
+ gopathpkg := filepath.Join(gopath, "pkg")
+ if _, err := os.Stat(gopathpkg); err == nil && gopath != "" {
+ if err := writeDLLs(gopathpkg); err == nil {
+ return gopathpkg, nil
+ }
+ }
+ debug.Printf("DLLs could not be written to GOPATH")
+
+ // Third, pick a temporary directory.
+ tmp := os.TempDir()
+ if err := writeDLLs(tmp); err != nil {
+ return "", fmt.Errorf("gl: unable to install ANGLE DLLs: %v", err)
+ }
+ return tmp, nil
+}
+
+func appdataPath() string {
+ return filepath.Join(os.Getenv("LOCALAPPDATA"), "GoGL", runtime.GOARCH)
+}
+
+func findDLLs() (err error) {
+ load := func(path string) (bool, error) {
+ if path != "" {
+ LibGLESv2.Name = filepath.Join(path, filepath.Base(LibGLESv2.Name))
+ LibEGL.Name = filepath.Join(path, filepath.Base(LibEGL.Name))
+ }
+ if err := LibGLESv2.Load(); err == nil {
+ if err := LibEGL.Load(); err != nil {
+ return false, fmt.Errorf("gl: loaded libglesv2 but not libegl: %v", err)
+ }
+ if path == "" {
+ debug.Printf("DLLs found")
+ } else {
+ debug.Printf("DLLs found in: %q", path)
+ }
+ return true, nil
+ }
+ return false, nil
+ }
+
+ // Look in the system directory.
+ if ok, err := load(""); ok || err != nil {
+ return err
+ }
+
+ // Look in the AppData directory.
+ if ok, err := load(appdataPath()); ok || err != nil {
+ return err
+ }
+
+ // TODO: Look for a Chrome installation.
+
+ // Look in GOPATH/pkg.
+ if ok, err := load(filepath.Join(os.Getenv("GOPATH"), "pkg")); ok || err != nil {
+ return err
+ }
+
+ // Look in temporary directory.
+ if ok, err := load(os.TempDir()); ok || err != nil {
+ return err
+ }
+
+ // Download the DLL binary.
+ path, err := downloadDLLs()
+ if err != nil {
+ return err
+ }
+ debug.Printf("DLLs written to %s", path)
+ if ok, err := load(path); !ok || err != nil {
+ return fmt.Errorf("gl: unable to load ANGLE after installation: %v", err)
+ }
+ return nil
+}
diff --git a/gl/work_windows.go b/gl/work_windows.go
index b3e7aee..53c434e 100644
--- a/gl/work_windows.go
+++ b/gl/work_windows.go
@@ -24,6 +24,9 @@
func (ctx *context) WorkAvailable() <-chan struct{} { return ctx.workAvailable }
func NewContext() (Context, Worker) {
+ if err := findDLLs(); err != nil {
+ panic(err)
+ }
glctx := &context{
workAvailable: make(chan struct{}, 1),
work: make(chan call, 3),
@@ -393,10 +396,17 @@
return ret
}
-// TODO: export LibGLESv2/LibEGL lazy DLLs, and come up with a loading scheme.
+// Exported libraries for a Windows GUI driver.
+//
+// LibEGL is not used directly by the gl package, but is needed by any
+// driver hoping to use OpenGL ES.
+var (
+ LibGLESv2 = syscall.NewLazyDLL("libglesv2.dll")
+ LibEGL = syscall.NewLazyDLL("libegl.dll")
+)
var (
- libGLESv2 = syscall.NewLazyDLL("libGLESv2.dll")
+ libGLESv2 = LibGLESv2
glActiveTexture = libGLESv2.NewProc("glActiveTexture")
glAttachShader = libGLESv2.NewProc("glAttachShader")
glBindAttribLocation = libGLESv2.NewProc("glBindAttribLocation")
