From 0bf228b0304fc5186dca3f3ec72ab20708a31220 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 10 Sep 2022 15:16:11 +0530
Subject: [PATCH] Wayland: Micro-optimization: Assume window will be shown on
 primary monitor so create it with its scale set to that of the primary
 monitor

---
 glfw/wl_window.c | 23 ++++++++++++++++++-----
 kitty/glfw.c     |  5 +++++
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/glfw/wl_window.c b/glfw/wl_window.c
index cd21e465d..4939906aa 100644
--- a/glfw/wl_window.c
+++ b/glfw/wl_window.c
@@ -380,11 +380,22 @@ static bool createSurface(_GLFWwindow* window,
 
     wl_surface_set_user_data(window->wl.surface, window);
 
+    // If we already have been notified of the primary monitor scale, assume
+    // the window will be created on it and so avoid a rescale roundtrip in the common
+    // case of the window being shown on the primary monitor or all monitors having the same scale.
+    // If you change this also change get_window_content_scale() in the kitty code.
+    GLFWmonitor* monitor = glfwGetPrimaryMonitor();
+    float xscale = 1.0, yscale = 1.0;
+    int scale = 1;
+    if (monitor) {
+        glfwGetMonitorContentScale(monitor, &xscale, &yscale);
+        // see wl_monitor.c xscale is always == yscale
+        if (xscale <= 0.0001 || xscale != xscale || xscale >= 24) xscale = 1.0;
+        if (xscale > 1) scale = (int)xscale;
+    }
 
-    debug("Creating window at size: %dx%d and scale 1\n", wndconfig->width, wndconfig->height);
-    window->wl.native = wl_egl_window_create(window->wl.surface,
-                                             wndconfig->width,
-                                             wndconfig->height);
+    debug("Creating window at size: %dx%d and scale %d\n", wndconfig->width, wndconfig->height, scale);
+    window->wl.native = wl_egl_window_create(window->wl.surface, wndconfig->width * scale, wndconfig->height * scale);
     if (!window->wl.native)
         return false;
 
@@ -392,11 +403,13 @@ static bool createSurface(_GLFWwindow* window,
     window->wl.height = wndconfig->height;
     window->wl.user_requested_content_size.width = wndconfig->width;
     window->wl.user_requested_content_size.height = wndconfig->height;
-    window->wl.scale = 1;
+
+    window->wl.scale = scale;
 
     if (!window->wl.transparent)
         setOpaqueRegion(window, false);
 
+    wl_surface_set_buffer_scale(window->wl.surface, scale);
     return true;
 }
 
diff --git a/kitty/glfw.c b/kitty/glfw.c
index 6193d684a..ea489a3b0 100644
--- a/kitty/glfw.c
+++ b/kitty/glfw.c
@@ -641,6 +641,7 @@ set_os_window_size(OSWindow *os_window, int x, int y) {
 
 static void
 get_window_content_scale(GLFWwindow *w, float *xscale, float *yscale, double *xdpi, double *ydpi) {
+    // if you change this function also change createSurface() in wl_window.c
     *xscale = 1; *yscale = 1;
     if (w) glfwGetWindowContentScale(w, xscale, yscale);
     else {
@@ -841,6 +842,10 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
     if (!global_state.is_wayland) {
         // On Wayland windows dont get a content scale until they receive an enterEvent anyway
         // which won't happen until the event loop ticks, so using a temp window is useless.
+        // The glfw backend assigns new windows a scale matching the primary monitor or 1 if
+        // no monitor has yet been reported. This is mimiced by get_window_content_scale() when
+        // using a null window, so we will match. Lets hope neither of these two change their algorithms
+        // in the future.
         temp_window = glfwCreateWindow(640, 480, "temp", NULL, common_context);
         if (temp_window == NULL) { fatal("Failed to create GLFW temp window! This usually happens because of old/broken OpenGL drivers. kitty requires working OpenGL 3.3 drivers."); }
     }