Wayland: panel kitten: Fix incorrect initial font size on compositors such as Hyprland that set scale late in the window creation process

Fixes #8496

docs/changelog.rst

@@ -103,6 +103,9 @@ Detailed list of changes
 - Fix a regression that caused tab bar margins to not be properly blanked when
   the tab bar is at the bottom (:iss:`8494`)
 
+- Wayland: panel kitten: Fix incorrect initial font size on compositors such as Hyprland
+  that set scale late in the window creation process (:iss:`8496`)
+
 
 0.41.0 [2025-03-29]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

glfw/glfw.py

@@ -323,6 +323,7 @@ def generate_wrappers(glfw_header: str) -> None:
     void glfwWaylandRunWithActivationToken(GLFWwindow *handle, GLFWactivationcallback cb, void *cb_data)
     bool glfwWaylandSetTitlebarColor(GLFWwindow *handle, uint32_t color, bool use_system_color)
     void glfwWaylandRedrawCSDWindowTitle(GLFWwindow *handle)
+    bool glfwWaylandIsWindowFullyCreated(GLFWwindow *handle)
     void glfwWaylandSetupLayerShellForNextWindow(const GLFWLayerShellConfig *c)
     pid_t glfwWaylandCompositorPID(void)
     unsigned long long glfwDBusUserNotify(const GLFWDBUSNotificationData *n, GLFWDBusnotificationcreatedfun callback, void *data)

glfw/glfw3.h

@@ -1320,6 +1320,7 @@ typedef struct GLFWLayerShellConfig {
     int requested_exclusive_zone;
     unsigned override_exclusive_zone;
     void (*size_callback)(GLFWwindow *window, const struct GLFWLayerShellConfig *config, unsigned monitor_width, unsigned monitor_height, uint32_t *width, uint32_t *height);
+    struct { double xdpi, ydpi, xscale, yscale; } expected;
 } GLFWLayerShellConfig;
 
 typedef struct GLFWDBUSNotificationData {

glfw/wl_window.c

@@ -2819,6 +2819,8 @@ GLFWAPI void glfwWaylandSetupLayerShellForNextWindow(const GLFWLayerShellConfig
     layer_shell_config_for_next_window = *c;
 }
 
+GLFWAPI bool glfwWaylandIsWindowFullyCreated(GLFWwindow *handle) { return handle != NULL && ((_GLFWwindow*)handle)->wl.window_fully_created; }
+
 void
 _glfwPlatformInputColorScheme(GLFWColorScheme appearance UNUSED) {
     _GLFWwindow* window = _glfw.windowListHead;

kitty/glfw-wrapper.c

@@ -485,6 +485,9 @@ load_glfw(const char* path) {
     *(void **) (&glfwWaylandRedrawCSDWindowTitle_impl) = dlsym(handle, "glfwWaylandRedrawCSDWindowTitle");
     if (glfwWaylandRedrawCSDWindowTitle_impl == NULL) dlerror(); // clear error indicator
 
+    *(void **) (&glfwWaylandIsWindowFullyCreated_impl) = dlsym(handle, "glfwWaylandIsWindowFullyCreated");
+    if (glfwWaylandIsWindowFullyCreated_impl == NULL) dlerror(); // clear error indicator
+
     *(void **) (&glfwWaylandSetupLayerShellForNextWindow_impl) = dlsym(handle, "glfwWaylandSetupLayerShellForNextWindow");
     if (glfwWaylandSetupLayerShellForNextWindow_impl == NULL) dlerror(); // clear error indicator
 

kitty/glfw-wrapper.h

@@ -1058,6 +1058,7 @@ typedef struct GLFWLayerShellConfig {
     int requested_exclusive_zone;
     unsigned override_exclusive_zone;
     void (*size_callback)(GLFWwindow *window, const struct GLFWLayerShellConfig *config, unsigned monitor_width, unsigned monitor_height, uint32_t *width, uint32_t *height);
+    struct { double xdpi, ydpi, xscale, yscale; } expected;
 } GLFWLayerShellConfig;
 
 typedef struct GLFWDBUSNotificationData {
@@ -2339,6 +2340,10 @@ typedef void (*glfwWaylandRedrawCSDWindowTitle_func)(GLFWwindow*);
 GFW_EXTERN glfwWaylandRedrawCSDWindowTitle_func glfwWaylandRedrawCSDWindowTitle_impl;
 #define glfwWaylandRedrawCSDWindowTitle glfwWaylandRedrawCSDWindowTitle_impl
 
+typedef bool (*glfwWaylandIsWindowFullyCreated_func)(GLFWwindow*);
+GFW_EXTERN glfwWaylandIsWindowFullyCreated_func glfwWaylandIsWindowFullyCreated_impl;
+#define glfwWaylandIsWindowFullyCreated glfwWaylandIsWindowFullyCreated_impl
+
 typedef void (*glfwWaylandSetupLayerShellForNextWindow_func)(const GLFWLayerShellConfig*);
 GFW_EXTERN glfwWaylandSetupLayerShellForNextWindow_func glfwWaylandSetupLayerShellForNextWindow_impl;
 #define glfwWaylandSetupLayerShellForNextWindow glfwWaylandSetupLayerShellForNextWindow_impl

kitty/glfw.c

@@ -1106,11 +1106,14 @@ calculate_layer_shell_window_size(
         if (!*height) *height = monitor_height;
         return;
     }
-    float xscale, yscale;
-    glfwGetWindowContentScale(window, &xscale, &yscale);
-    double xdpi, ydpi;
-    dpi_from_scale(xscale, yscale, &xdpi, &ydpi);
+    float xscale = (float)config->expected.xscale, yscale = (float)config->expected.yscale;
+    double xdpi = config->expected.xdpi, ydpi = config->expected.ydpi;
+    if (glfwWaylandIsWindowFullyCreated(window)) {
+        glfwGetWindowContentScale(window, &xscale, &yscale);
+        dpi_from_scale(xscale, yscale, &xdpi, &ydpi);
+    }
     OSWindow *os_window = os_window_for_glfw_window(window);
+    debug("Calculating layer shell window size at scale: %f\n", xscale);
     FONTS_DATA_HANDLE fonts_data = load_fonts_data(os_window ? os_window->fonts_data->font_sz_in_pts : OPT(font_size), xdpi, ydpi);
     if (config->edge == GLFW_EDGE_LEFT || config->edge == GLFW_EDGE_RIGHT) {
         if (!*height) *height = monitor_height;
@@ -1273,6 +1276,7 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
     if (is_layer_shell) {
         GLFWLayerShellConfig lsc = {0};
         if (!translate_layer_shell_config(layer_shell_config, &lsc)) return NULL;
+        lsc.expected.xdpi = xdpi; lsc.expected.ydpi = ydpi; lsc.expected.xscale = xscale; lsc.expected.yscale = yscale;
         glfwWaylandSetupLayerShellForNextWindow(&lsc);
     }
     GLFWwindow *glfw_window = glfwCreateWindow(width, height, title, NULL, temp_window ? temp_window : common_context);
@@ -1303,8 +1307,10 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
         float n_xscale, n_yscale;
         double n_xdpi, n_ydpi;
         get_window_content_scale(glfw_window, &n_xscale, &n_yscale, &n_xdpi, &n_ydpi);
-        if (n_xdpi != xdpi || n_ydpi != ydpi) {
+        if (n_xdpi != xdpi || n_ydpi != ydpi || is_layer_shell) {
             // this can happen if the window is moved by the OS to a different monitor when shown or with fractional scales on Wayland
+            // it can also happen with layer shell windows if the callback is
+            // called before the window is fully created
             xdpi = n_xdpi; ydpi = n_ydpi;
             fonts_data = load_fonts_data(OPT(font_size), xdpi, ydpi);
         }