From f794fc8d6608a351b5045ac422f0b401e4b10dd7 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 5 Jul 2020 15:00:56 +0900
Subject: [PATCH] uidriver/glfw: Set No-API when creating a hidden window first

GLFW tries to create an OpenGL context by default when creating a
window. This is not necessary when OpenGL is not used. This is an
optimization by skipping to create an OpenGL context if possible.

Fixes #1237
---
 internal/glfw/const.go       | 1 +
 internal/uidriver/glfw/ui.go | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/internal/glfw/const.go b/internal/glfw/const.go
index 252b8fbbb..0069dba35 100644
--- a/internal/glfw/const.go
+++ b/internal/glfw/const.go
@@ -97,6 +97,7 @@ const (
 	CursorHidden   = 0x00034002
 	CursorNormal   = 0x00034001
 	NoAPI          = 0
+	OpenGLAPI      = 0x00030001
 )
 
 const (
diff --git a/internal/uidriver/glfw/ui.go b/internal/uidriver/glfw/ui.go
index 07f0e86a4..9b733223b 100644
--- a/internal/uidriver/glfw/ui.go
+++ b/internal/uidriver/glfw/ui.go
@@ -129,6 +129,7 @@ func initialize() error {
 		return err
 	}
 	glfw.WindowHint(glfw.Visible, glfw.False)
+	glfw.WindowHint(glfw.ClientAPI, glfw.NoAPI)
 
 	// Create a window to set the initial monitor.
 	w, err := glfw.CreateWindow(16, 16, "", nil, nil)
@@ -657,6 +658,7 @@ func (u *UserInterface) run(context driver.UIContext) error {
 		u.window = nil
 
 		if u.Graphics().IsGL() {
+			glfw.WindowHint(glfw.ClientAPI, glfw.OpenGLAPI)
 			glfw.WindowHint(glfw.ContextVersionMajor, 2)
 			glfw.WindowHint(glfw.ContextVersionMinor, 1)
 		} else {