From fe8cf46d566028346003187a81571c87223778b5 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 25 May 2018 21:59:31 +0530
Subject: [PATCH] Handle window DPI changes

---
 kitty/boss.py | 14 +++++++-------
 kitty/glfw.c  | 25 +++++++++++++------------
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/kitty/boss.py b/kitty/boss.py
index 2a2cca55a..1e07b9dd3 100644
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -100,20 +100,17 @@ class Boss:
         self.add_os_window(startup_session, os_window_id=os_window_id)
 
     def add_os_window(self, startup_session, os_window_id=None, wclass=None, wname=None, size=None, startup_id=None):
-        dpi_changed = False
         if os_window_id is None:
             w, h = initial_window_size(self.opts, self.cached_values) if size is None else size
             cls = wclass or self.args.cls or appname
             os_window_id = create_os_window(w, h, appname, wname or self.args.name or cls, cls)
             if startup_id:
                 ctx = init_startup_notification(os_window_id, startup_id)
-            dpi_changed = show_window(os_window_id)
+            show_window(os_window_id)
             if startup_id:
                 end_startup_notification(ctx)
         tm = TabManager(os_window_id, self.opts, self.args, startup_session)
         self.os_window_map[os_window_id] = tm
-        if dpi_changed:
-            self.on_dpi_change(os_window_id)
         return os_window_id
 
     def list_os_windows(self):
@@ -305,9 +302,12 @@ class Boss:
             tm.activate_tab_at(x)
 
     def on_window_resize(self, os_window_id, w, h, dpi_changed):
-        tm = self.os_window_map.get(os_window_id)
-        if tm is not None:
-            tm.resize()
+        if dpi_changed:
+            self.on_dpi_change(os_window_id)
+        else:
+            tm = self.os_window_map.get(os_window_id)
+            if tm is not None:
+                tm.resize()
 
     def increase_font_size(self):  # legacy
         self.set_font_size(min(self.opts.font_size * 5, self.current_font_size + 2.0))
diff --git a/kitty/glfw.c b/kitty/glfw.c
index a0dcfd544..bf3a853ad 100644
--- a/kitty/glfw.c
+++ b/kitty/glfw.c
@@ -103,6 +103,17 @@ framebuffer_size_callback(GLFWwindow *w, int width, int height) {
     global_state.callback_os_window = NULL;
 }
 
+static void
+dpi_change_callback(GLFWwindow *w, float x_scale UNUSED, float y_scale UNUSED) {
+    if (!set_callback_window(w)) return;
+    // Ensure update_os_window_viewport() is called in the near future, it will
+    // take care of DPI changes.
+    OSWindow *window = global_state.callback_os_window;
+    window->has_pending_resizes = true; global_state.has_pending_resizes = true;
+    window->last_resize_event_at = monotonic();
+    global_state.callback_os_window = NULL;
+}
+
 static void
 refresh_callback(GLFWwindow *w) {
     if (!set_callback_window(w)) return;
@@ -408,6 +419,7 @@ create_os_window(PyObject UNUSED *self, PyObject *args) {
     glfwSetCursor(glfw_window, standard_cursor);
     update_os_window_viewport(w, false);
     glfwSetFramebufferSizeCallback(glfw_window, framebuffer_size_callback);
+    glfwSetWindowContentScaleCallback(glfw_window, dpi_change_callback);
     glfwSetWindowRefreshCallback(glfw_window, refresh_callback);
     glfwSetMouseButtonCallback(glfw_window, mouse_button_callback);
     glfwSetScrollCallback(glfw_window, scroll_callback);
@@ -440,30 +452,19 @@ static PyObject*
 show_window(PyObject UNUSED *self, PyObject *args) {
     id_type os_window_id;
     int yes = 1;
-    bool dpi_changed = false;
     if (!PyArg_ParseTuple(args, "K|p", &os_window_id, &yes)) return NULL;
     for (size_t i = 0; i < global_state.num_os_windows; i++) {
         OSWindow *w = global_state.os_windows + i;
         if (w->id == os_window_id) {
             if (yes) {
-                bool first_show = !w->shown_once;
                 glfwShowWindow(w->handle);
                 w->shown_once = true;
                 push_focus_history(w);
-                if (first_show) {
-                    double before_x = w->logical_dpi_x, before_y = w->logical_dpi_y;
-                    set_os_window_dpi(w);
-                    dpi_changed = before_x != w->logical_dpi_x || before_y != w->logical_dpi_y;
-                    if (dpi_changed) load_fonts_for_window(w);
-                    w->has_pending_resizes = true;
-                    global_state.has_pending_resizes = true;
-                }
             } else glfwHideWindow(w->handle);
             break;
         }
     }
-    if (dpi_changed) Py_RETURN_TRUE;
-    Py_RETURN_FALSE;
+    Py_RETURN_NONE;
 }
 
 void