Use glfwGetMonitorWorkarea for accurate screen size

CHANGELOG.md

@@ -1,4 +1,5 @@
 ## Main
+-   Use glfwGetMonitorWorkarea for accurate screen size in GetScreenSize and remove unusable_height estimation hack (PR #7469)
 -   Upgrade stdgpu third-party library to commit d7c07d0.
 -   Fix performance for non-contiguous NumPy array conversion in pybind vector converters. This change removes restrictive `py::array::c_style` flags and adds a runtime contiguity check, improving Pandas-to-Open3D conversion speed by up to ~50×. (issue #5250)(PR #7343).
 -   Corrected documentation for Link Open3D in C++ projects (broken links).

cpp/open3d/visualization/gui/GLFWWindowSystem.cpp

@@ -130,16 +130,9 @@ Size GLFWWindowSystem::GetScreenSize(OSWindow w) {
         monitor = glfwGetPrimaryMonitor();
     }
     if (monitor) {
-        const GLFWvidmode* mode = glfwGetVideoMode(monitor);
-        if (mode) {
-            screen_width = mode->width;
-            screen_height = mode->height;
-        }
-        // TODO: if we can update GLFW we can replace the above with this
-        //       Also, see below.
-        // int xpos, ypos;
-        // glfwGetMonitorWorkarea(monitor, &xpos, &ypos,
-        //                       &screen_width, &screen_height);
+        int xpos, ypos;
+        glfwGetMonitorWorkarea(monitor, &xpos, &ypos,
+                               &screen_width, &screen_height);
     }
 
     return Size(screen_width, screen_height);

cpp/open3d/visualization/gui/Window.cpp

@@ -991,13 +991,7 @@ void Window::OnResize() {
 
             w = std::min(screen_size.width,
                          int(std::round(pref.width / impl_->imgui_.scaling)));
-            // screen_height is the screen height, not the usable screen height.
-            // If we cannot call glfwGetMonitorWorkarea(), then we need to guess
-            // at the size. The window titlebar is about 2 * em, and then there
-            // is often a global menubar (Linux/GNOME, macOS) or a toolbar
-            // (Windows). A toolbar is somewhere around 2 - 3 ems.
-            int unusable_height = 4 * impl_->theme_.font_size;
-            h = std::min(screen_size.height - unusable_height,
+            h = std::min(screen_size.height,
                          int(std::round(pref.height / impl_->imgui_.scaling)));
             ws.SetWindowSize(impl_->window_, w, h);
         }