Backends: GLFW: improve workarounds for cases where GLFW is unable to provide reliable monitor info. (#9195, #7902, #5683)
diff --git a/backends/imgui_impl_glfw.cpp b/backends/imgui_impl_glfw.cpp
index d0d21d3..24b5104 100644
--- a/backends/imgui_impl_glfw.cpp
+++ b/backends/imgui_impl_glfw.cpp
@@ -32,6 +32,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+// 2026-01-25: [Docking] Improve workarounds for cases where GLFW is unable to provide any reliable monitor info. Preserve existing monitor list when none of the new one is valid. (#9195, #7902, #5683)
// 2026-01-18: [Docking] Dynamically load X11 functions to avoid -lx11 linking requirement introduced on 2025-09-10.
// 2025-12-12: Added IMGUI_IMPL_GLFW_DISABLE_X11 / IMGUI_IMPL_GLFW_DISABLE_WAYLAND to forcefully disable either.
// 2025-12-10: Avoid repeated glfwSetCursor()/glfwSetInputMode() calls when unnecessary. Lowers overhead for very high framerates (e.g. 10k+ FPS).
@@ -1071,13 +1072,10 @@
static void ImGui_ImplGlfw_UpdateMonitors()
{
ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
-
int monitors_count = 0;
GLFWmonitor** glfw_monitors = glfwGetMonitors(&monitors_count);
- if (monitors_count == 0) // Preserve existing monitor list if there are none. Happens on macOS sleeping (#5683)
- return;
- platform_io.Monitors.resize(0);
+ bool updated_monitors = false;
for (int n = 0; n < monitors_count; n++)
{
ImGuiPlatformMonitor monitor;
@@ -1086,6 +1084,8 @@
const GLFWvidmode* vid_mode = glfwGetVideoMode(glfw_monitors[n]);
if (vid_mode == nullptr)
continue; // Failed to get Video mode (e.g. Emscripten does not support this function)
+ if (vid_mode->width <= 0 || vid_mode->height <= 0)
+ continue; // Failed to query suitable monitor info (#9195)
monitor.MainPos = monitor.WorkPos = ImVec2((float)x, (float)y);
monitor.MainSize = monitor.WorkSize = ImVec2((float)vid_mode->width, (float)vid_mode->height);
#if GLFW_HAS_MONITOR_WORK_AREA
@@ -1099,9 +1099,15 @@
#endif
float scale = ImGui_ImplGlfw_GetContentScaleForMonitor(glfw_monitors[n]);
if (scale == 0.0f)
- continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
+ continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0 (#7902)
monitor.DpiScale = scale;
monitor.PlatformHandle = (void*)glfw_monitors[n]; // [...] GLFW doc states: "guaranteed to be valid only until the monitor configuration changes"
+
+ // Preserve existing monitor list until a valid one is added.
+ // Happens on macOS sleeping (#5683) and seemingly occasionally on Windows (#9195)
+ if (!updated_monitors)
+ platform_io.Monitors.resize(0);
+ updated_monitors = false;
platform_io.Monitors.push_back(monitor);
}
}
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index 9d5544e..d51ba8d 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -240,6 +240,8 @@
- Backends:
- GLFW: dynamically load X11 functions to avoid -lx11 linking requirement introduced
in 1.92.3. (#9116, #9109) [@ramenguy99]
+ - GLFW: improve workarounds for cases where GLFW is unable to provide reliable monitor
+ info. Preserve existing monitor list when none of the new one is valid. (#9195, #7902, #5683)
- SDL2, SDL3: adjust IME offset to match other backends and master branch. (#6071, #1953)
- Win32: viewports created by backend forcefully direct messages to
DefWindowProcW() in order to support Unicode text input. (#9099, #3653, #5961) [@ulhc]
