From f7a8c7efa642ce755bdb8704d6525214522eef4d Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Mon, 5 Jun 2017 00:06:40 +0900
Subject: [PATCH] ui: Avoid recalc the scale factor

---
 internal/ui/ui_glfw.go | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/internal/ui/ui_glfw.go b/internal/ui/ui_glfw.go
index 4dc8a13f8..43452c164 100644
--- a/internal/ui/ui_glfw.go
+++ b/internal/ui/ui_glfw.go
@@ -35,6 +35,7 @@ type userInterface struct {
 	height      int
 	scale       float64
 	deviceScale float64
+	glfwScale   float64
 	funcs       chan func()
 	running     bool
 	sizeChanged bool
@@ -201,7 +202,10 @@ func Run(width, height int, scale float64, title string, g GraphicsContext) erro
 }
 
 func (u *userInterface) glfwSize() (int, int) {
-	return int(float64(u.width) * u.scale * glfwScale()), int(float64(u.height) * u.scale * glfwScale())
+	if u.glfwScale == 0 {
+		u.glfwScale = glfwScale()
+	}
+	return int(float64(u.width) * u.scale * u.glfwScale), int(float64(u.height) * u.scale * u.glfwScale)
 }
 
 func (u *userInterface) actualScreenScale() float64 {
@@ -213,7 +217,10 @@ func (u *userInterface) actualScreenScale() float64 {
 
 func (u *userInterface) pollEvents() {
 	glfw.PollEvents()
-	currentInput.update(u.window, u.scale*glfwScale())
+	if u.glfwScale == 0 {
+		u.glfwScale = glfwScale()
+	}
+	currentInput.update(u.window, u.scale*u.glfwScale)
 }
 
 func (u *userInterface) update(g GraphicsContext) error {