From 6bcdd3177ddb721f51958fbe9cfa35f04fad6040 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 26 Jan 2020 18:04:25 -0500
Subject: [PATCH] Ensures that a change of screen issues a `reshape`. Just in
 case.

Thereby resolves display mis-sizing when dragging from a Retina display to a regular one, or vice versa.
---
 OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m b/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m
index 283f6e19b..5f4267c3a 100644
--- a/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m	
+++ b/OSBindings/Mac/Clock Signal/Views/CSOpenGLView.m	
@@ -17,6 +17,7 @@
 @implementation CSOpenGLView {
 	CVDisplayLinkRef _displayLink;
 	CGSize _backingSize;
+	NSScreen *_currentScreen;
 
 	NSTrackingArea *_mouseTrackingArea;
 	NSTimer *_mouseHideTimer;
@@ -26,6 +27,9 @@
 - (void)prepareOpenGL {
 	[super prepareOpenGL];
 
+	// Note the initial screen.
+	_currentScreen = self.window.screen;
+
 	// Synchronize buffer swaps with vertical refresh rate
 	GLint swapInt = 1;
 	[[self openGLContext] setValues:&swapInt forParameter:NSOpenGLCPSwapInterval];
@@ -56,6 +60,14 @@ static CVReturn DisplayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeSt
 }
 
 - (void)drawAtTime:(const CVTimeStamp *)now frequency:(double)frequency {
+	if(self.window.screen != _currentScreen) {
+		_currentScreen = self.window.screen;
+
+		// Issue a reshape, in case a switch to/from a Retina display has
+		// happened, changing the results of -convertSizeToBacking:, etc.
+		[self reshape];
+	}
+
 	[self redrawWithEvent:CSOpenGLViewRedrawEventTimer];
 }