From d8be26efe64adbafdb91c5504ec6f318f110736a Mon Sep 17 00:00:00 2001
From: ohadrau <ohadrau@yahoo.com>
Date: Sun, 20 Jan 2019 15:33:40 -0500
Subject: [PATCH] Add Window.takeScreenshot

---
 src/Core/Window.re | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/Core/Window.re b/src/Core/Window.re
index 9d86926b2..9464d2c04 100644
--- a/src/Core/Window.re
+++ b/src/Core/Window.re
@@ -326,11 +326,17 @@ let getDevicePixelRatio = (w: t) => {
 let takeScreenshot = (w: t, filename: string) => {
   open Glfw;
 
-  let {width, height}: Window.frameBufferSize = glfwGetFramebufferSize(w.glfwWindow);
+  let width = w.framebufferWidth;
+  let height = w.framebufferHeight;
 
   let image = Image.create(~width, ~height, ~numChannels=4, ~channelSize=1);
   let buffer = Image.getBuffer(image);
 
+  /* WebGL is weird in that we can't capture with glReadPixels during
+     a render operation. Instead, we want to wait till it's over (we
+     can force this by triggering a new render) and then taking the
+     screenshot */
+  render(w);
   glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
 
   Image.save(image, filename);