NSGL: Update current display for display link

This solution of one display link per window is far from ideal but is
still better than no solution.

As a side-effect this fixes swap interval breaking being ignored for
occluded windows on earlier versions of macOS.

Fixes #680.
Fixes #1337.
Related to #1417.
Fixes #1435.

src/cocoa_monitor.m

@@ -32,8 +32,6 @@
 #include <math.h>
 
 #include <IOKit/graphics/IOGraphicsLib.h>
-#include <CoreVideo/CVBase.h>
-#include <CoreVideo/CVDisplayLink.h>
 #include <ApplicationServices/ApplicationServices.h>
 
 

src/cocoa_platform.h

@@ -28,6 +28,9 @@
 #include <dlfcn.h>
 
 #include <Carbon/Carbon.h>
+#include <CoreVideo/CVBase.h>
+#include <CoreVideo/CVDisplayLink.h>
+
 #if defined(__OBJC__)
 #import <Cocoa/Cocoa.h>
 #else

src/cocoa_window.m

@@ -338,6 +338,12 @@ static const NSRange kEmptyRange = { NSNotFound, 0 };
     _glfwInputWindowFocus(window, GLFW_FALSE);
 }
 
+- (void)windowDidChangeScreen:(NSNotification *)notification
+{
+    if (window->context.source == GLFW_NATIVE_CONTEXT_API)
+        _glfwUpdateDisplayLinkDisplayNSGL(window);
+}
+
 @end
 
 

src/nsgl_context.h

@@ -27,8 +27,6 @@
 #define _GLFW_PLATFORM_CONTEXT_STATE            _GLFWcontextNSGL nsgl
 #define _GLFW_PLATFORM_LIBRARY_CONTEXT_STATE    _GLFWlibraryNSGL nsgl
 
-#import <CoreVideo/CoreVideo.h>
-
 #include <stdatomic.h>
 
 
@@ -61,4 +59,5 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
                                 const _GLFWctxconfig* ctxconfig,
                                 const _GLFWfbconfig* fbconfig);
 void _glfwDestroyContextNSGL(_GLFWwindow* window);
+void _glfwUpdateDisplayLinkDisplayNSGL(_GLFWwindow* window);
 

src/nsgl_context.m

@@ -367,6 +367,8 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
 
     [window->context.nsgl.object setView:window->ns.view];
 
+    window->context.nsgl.swapIntervalCond = [NSCondition new];
+
     window->context.makeCurrent = makeContextCurrentNSGL;
     window->context.swapBuffers = swapBuffersNSGL;
     window->context.swapInterval = swapIntervalNSGL;
@@ -378,16 +380,22 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
     CVDisplayLinkSetOutputCallback(window->context.nsgl.displayLink,
                                    &displayLinkCallback,
                                    window);
-    CVDisplayLinkSetCurrentCGDisplayFromOpenGLContext(window->context.nsgl.displayLink,
-                                                      (CGLContextObj) window->context.nsgl.object,
-                                                      (CGLPixelFormatObj) window->context.nsgl.pixelFormat);
     CVDisplayLinkStart(window->context.nsgl.displayLink);
 
-    window->context.nsgl.swapIntervalCond = [NSCondition new];
+    _glfwUpdateDisplayLinkDisplayNSGL(window);
-
     return GLFW_TRUE;
 }
 
+void _glfwUpdateDisplayLinkDisplayNSGL(_GLFWwindow* window)
+{
+    CGDirectDisplayID displayID =
+        [[[window->ns.object screen] deviceDescription][@"NSScreenNumber"] unsignedIntValue];
+    if (!displayID)
+        return;
+
+    CVDisplayLinkSetCurrentCGDisplay(window->context.nsgl.displayLink, displayID);
+}
+
 
 //////////////////////////////////////////////////////////////////////////
 //////                        GLFW native API                       //////