Add a function to get the monitor on which a window is currently being displayed

include/GLFW/glfw3.h

@@ -3898,6 +3898,26 @@ GLFWAPI void glfwFocusWindow(GLFWwindow* window);
  */
 GLFWAPI void glfwRequestWindowAttention(GLFWwindow* window);
 
+/*! @brief Returns the monitor on which the window is being currently displayed.
+ *
+ *  The window should not be NULL.
+ *
+ *  @param[in] window The window to query.
+ *  @return The monitor, or `NULL` if the window is NULL or an
+ *  [error](@ref error_handling) occurred.
+ *
+ *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED.
+ *
+ *  @thread_safety This function must only be called from the main thread.
+ *
+ *  @sa @ref window_monitor
+ *
+ *  @since Added in version 3.4.
+ *
+ *  @ingroup window
+ */
+GLFWAPI GLFWmonitor* glfwGetMonitorDisplayingWindow(GLFWwindow* window);
+
 /*! @brief Returns the monitor that the window uses for full screen mode.
  *
  *  This function returns the handle of the monitor that the specified window is

src/internal.h

@@ -724,6 +724,7 @@ struct _GLFWplatform
     void (*showWindow)(_GLFWwindow*);
     void (*hideWindow)(_GLFWwindow*);
     void (*requestWindowAttention)(_GLFWwindow*);
+    _GLFWmonitor* (*getMonitorDisplayingWindow)(_GLFWwindow*);
     void (*focusWindow)(_GLFWwindow*);
     void (*setWindowMonitor)(_GLFWwindow*,_GLFWmonitor*,int,int,int,int,int);
     GLFWbool (*windowFocused)(_GLFWwindow*);

src/null_init.c

@@ -89,6 +89,7 @@ GLFWbool _glfwConnectNull(int platformID, _GLFWplatform* platform)
         _glfwShowWindowNull,
         _glfwHideWindowNull,
         _glfwRequestWindowAttentionNull,
+        _glfwGetMonitorDisplayingWindowNull,
         _glfwFocusWindowNull,
         _glfwSetWindowMonitorNull,
         _glfwWindowFocusedNull,

src/null_platform.h

@@ -240,6 +240,7 @@ GLFWbool _glfwRawMouseMotionSupportedNull(void);
 void _glfwShowWindowNull(_GLFWwindow* window);
 void _glfwRequestWindowAttentionNull(_GLFWwindow* window);
 void _glfwRequestWindowAttentionNull(_GLFWwindow* window);
+_GLFWmonitor* _glfwGetMonitorDisplayingWindowNull(_GLFWwindow* window);
 void _glfwHideWindowNull(_GLFWwindow* window);
 void _glfwFocusWindowNull(_GLFWwindow* window);
 GLFWbool _glfwWindowFocusedNull(_GLFWwindow* window);

src/null_window.c

@@ -436,6 +436,11 @@ void _glfwRequestWindowAttentionNull(_GLFWwindow* window)
 {
 }
 
+_GLFWmonitor* _glfwGetMonitorDisplayingWindowNull(_GLFWwindow* window)
+{
+    return NULL;
+}
+
 void _glfwHideWindowNull(_GLFWwindow* window)
 {
     if (_glfw.null.focusedWindow == window)

src/win32_init.c

@@ -653,6 +653,7 @@ GLFWbool _glfwConnectWin32(int platformID, _GLFWplatform* platform)
         _glfwShowWindowWin32,
         _glfwHideWindowWin32,
         _glfwRequestWindowAttentionWin32,
+        _glfwGetMonitorDisplayingWindowWin32,
         _glfwFocusWindowWin32,
         _glfwSetWindowMonitorWin32,
         _glfwWindowFocusedWin32,

src/win32_platform.h

@@ -558,6 +558,7 @@ void _glfwMaximizeWindowWin32(_GLFWwindow* window);
 void _glfwShowWindowWin32(_GLFWwindow* window);
 void _glfwHideWindowWin32(_GLFWwindow* window);
 void _glfwRequestWindowAttentionWin32(_GLFWwindow* window);
+_GLFWmonitor* _glfwGetMonitorDisplayingWindowWin32(_GLFWwindow* window);
 void _glfwFocusWindowWin32(_GLFWwindow* window);
 void _glfwSetWindowMonitorWin32(_GLFWwindow* window, _GLFWmonitor* monitor, int xpos, int ypos, int width, int height, int refreshRate);
 GLFWbool _glfwWindowFocusedWin32(_GLFWwindow* window);

src/win32_window.c

@@ -1762,6 +1762,20 @@ void _glfwRequestWindowAttentionWin32(_GLFWwindow* window)
     FlashWindow(window->win32.handle, TRUE);
 }
 
+_GLFWmonitor* _glfwGetMonitorDisplayingWindowWin32(_GLFWwindow* window)
+{
+    int i;
+    HMONITOR monitor = MonitorFromWindow(window->win32.handle, MONITOR_DEFAULTTONEAREST);
+
+    for(i = 0; i < _glfw.monitorCount; ++i)
+    {
+        if(_glfw.monitors[i]->win32.handle == monitor)
+            return _glfw.monitors[i];
+    }
+
+    return NULL;
+}
+
 void _glfwFocusWindowWin32(_GLFWwindow* window)
 {
     BringWindowToTop(window->win32.handle);

src/window.c

@@ -822,6 +822,16 @@ GLFWAPI void glfwRequestWindowAttention(GLFWwindow* handle)
     _glfw.platform.requestWindowAttention(window);
 }
 
+GLFWAPI GLFWmonitor* glfwGetMonitorDisplayingWindow(GLFWwindow* handle)
+{
+    _GLFWwindow* const window = (_GLFWwindow*) handle;
+    assert(handle != NULL);
+
+    _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
+
+    return (GLFWmonitor*)_glfw.platform.getMonitorDisplayingWindow(window);
+}
+
 GLFWAPI void glfwHideWindow(GLFWwindow* handle)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;