Wayland: Fix reporting of monitor scale changes

Content scale events would be emitted when a window surface entered or
left an output, but not when one of a window's current outputs had its
scale changed.

README.md

@@ -353,6 +353,8 @@ information on what to include when reporting a bug.
    changed
  - [Wayland] Bugfix: `glfwTerminate` would segfault if any monitor had changed
    scale
+ - [Wayland] Bugfix: Window content scale events were not emitted when monitor
+   scale changed
  - [POSIX] Removed use of deprecated function `gettimeofday`
  - [POSIX] Bugfix: `CLOCK_MONOTONIC` was not correctly tested for or enabled
  - [WGL] Disabled the DWM swap interval hack for Windows 8 and later (#1072)

src/wl_monitor.c

@@ -113,6 +113,18 @@ static void outputHandleScale(void* userData,
     struct _GLFWmonitor* monitor = userData;
 
     monitor->wl.scale = factor;
+
+    for (_GLFWwindow* window = _glfw.windowListHead; window; window = window->next)
+    {
+        for (int i = 0; i < window->wl.monitorsCount; i++)
+        {
+            if (window->wl.monitors[i] == monitor)
+            {
+                _glfwUpdateContentScaleWayland(window);
+                break;
+            }
+        }
+    }
 }
 
 #ifdef WL_OUTPUT_NAME_SINCE_VERSION

src/wl_platform.h

@@ -507,6 +507,7 @@ GLFWbool _glfwGetGammaRampWayland(_GLFWmonitor* monitor, GLFWgammaramp* ramp);
 void _glfwSetGammaRampWayland(_GLFWmonitor* monitor, const GLFWgammaramp* ramp);
 
 void _glfwAddOutputWayland(uint32_t name, uint32_t version);
+void _glfwUpdateContentScaleWayland(_GLFWwindow* window);
 GLFWbool _glfwInputTextWayland(_GLFWwindow* window, uint32_t scancode);
 
 void _glfwAddSeatListenerWayland(struct wl_seat* seat);

src/wl_window.c

@@ -334,7 +334,7 @@ static void resizeWindow(_GLFWwindow* window)
     wl_surface_commit(window->wl.decorations.bottom.surface);
 }
 
-static void checkScaleChange(_GLFWwindow* window)
+void _glfwUpdateContentScaleWayland(_GLFWwindow* window)
 {
     if (_glfw.wl.compositorVersion < WL_SURFACE_SET_BUFFER_SCALE_SINCE_VERSION)
         return;
@@ -372,7 +372,7 @@ static void surfaceHandleEnter(void* userData,
 
     window->wl.monitors[window->wl.monitorsCount++] = monitor;
 
-    checkScaleChange(window);
+    _glfwUpdateContentScaleWayland(window);
 }
 
 static void surfaceHandleLeave(void* userData,
@@ -392,7 +392,7 @@ static void surfaceHandleLeave(void* userData,
     }
     window->wl.monitors[--window->wl.monitorsCount] = NULL;
 
-    checkScaleChange(window);
+    _glfwUpdateContentScaleWayland(window);
 }
 
 static const struct wl_surface_listener surfaceListener =