From 630101204b3a9d7c13e1df069991f45181235e5c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sat, 22 Jul 2023 11:20:37 +0530
Subject: [PATCH] macOS: Disable OS window shadows for transparent windows as
 they cause rendering artifacts due to Cocoa bugs

Fixes #6439
---
 docs/changelog.rst   |  2 ++
 glfw/cocoa_window.m  |  3 +++
 kitty/cocoa_window.m | 15 ---------------
 kitty/glfw.c         | 18 ------------------
 kitty/state.h        |  2 +-
 5 files changed, 6 insertions(+), 34 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 636dd938d..d8b3353db 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -40,6 +40,8 @@ Detailed list of changes
 
 - macOS: Fix a performance regression on M1 machines using outdated macOS versions (:iss:`6479`)
 
+- macOS: Disable OS window shadows for transparent windows as they cause rendering artifacts due to Cocoa bugs (:iss:`6439`)
+
 0.29.1 [2023-07-17]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/glfw/cocoa_window.m b/glfw/cocoa_window.m
index 890bad574..cfc3377c6 100644
--- a/glfw/cocoa_window.m
+++ b/glfw/cocoa_window.m
@@ -3029,6 +3029,9 @@ GLFWAPI void glfwCocoaSetWindowChrome(GLFWwindow *w, unsigned int color, bool us
             has_shadow = true;
             break;
     }
+    // shadow causes burn-in/ghosting because cocoa doesnt invalidate it on OS window resize/minimize/restore.
+    // https://github.com/kovidgoyal/kitty/issues/6439
+    if (is_transparent) has_shadow = false;
     bool hide_titlebar_buttons = !in_fullscreen && window->ns.titlebar_hidden;
     [window->ns.object setTitlebarAppearsTransparent:titlebar_transparent];
     [window->ns.object setHasShadow:has_shadow];
diff --git a/kitty/cocoa_window.m b/kitty/cocoa_window.m
index 1d3297970..be4d37b18 100644
--- a/kitty/cocoa_window.m
+++ b/kitty/cocoa_window.m
@@ -737,21 +737,6 @@ cocoa_focus_window(void *w) {
     [window makeKeyWindow];
 }
 
-bool
-cocoa_set_shadow(void *w, bool has_shadow) {
-    NSWindow *window = (NSWindow*)w;
-    bool current = window.hasShadow;
-    [window setHasShadow:has_shadow];
-    if (has_shadow) {  // invalidate the shadow to clear the ghosting
-        [window invalidateShadow];
-        // invalidateShadow does not work with layer backed views, see http://www.openradar.me/34184270
-        // so do the frame resize dance to force AppKit to invalidate the shadow even with the layer
-        [window setFrame:NSMakeRect(NSMinX(window.frame), NSMinY(window.frame), NSWidth(window.frame)+1, NSHeight(window.frame)) display:NO animate:NO];
-        [window setFrame:NSMakeRect(NSMinX(window.frame), NSMinY(window.frame), NSWidth(window.frame)-1, NSHeight(window.frame)) display:NO animate:NO];
-    }
-    return current;
-}
-
 long
 cocoa_window_number(void *w) {
     NSWindow *window = (NSWindow*)w;
diff --git a/kitty/glfw.c b/kitty/glfw.c
index 97b16f3ff..db73487dd 100644
--- a/kitty/glfw.c
+++ b/kitty/glfw.c
@@ -320,24 +320,6 @@ change_live_resize_state(OSWindow *w, bool in_progress) {
         w->live_resize.num_of_resize_events = 0;
         apply_swap_interval(in_progress ? 0 : -1);
 #ifdef __APPLE__
-        extern bool cocoa_set_shadow(void*, bool);
-        if (w->is_semi_transparent && w->handle) {
-            // shadow with transparency during resize causes burn-in of window contents
-            // aka ghosting of the text after resize is completed. So avoid that by turning
-            // the shadow on and off.
-            if (in_progress) {
-                bool had_shadow = cocoa_set_shadow(glfwGetCocoaWindow(w->handle), false);
-                w->has_cocoa_shadow = had_shadow;
-            } else {
-                if (w->has_cocoa_shadow) {
-                    // turning on the shadow will cause a resize event which will be delivered before cocoa_set_shadow returns
-                    w->ignore_resize_events = true;
-                    cocoa_set_shadow(glfwGetCocoaWindow(w->handle), true);
-                    w->ignore_resize_events = false;
-                    w->has_cocoa_shadow = false;
-                }
-            }
-        }
         cocoa_out_of_sequence_render(w);
 #endif
     }
diff --git a/kitty/state.h b/kitty/state.h
index 8d9ff007f..507d3fa76 100644
--- a/kitty/state.h
+++ b/kitty/state.h
@@ -229,7 +229,7 @@ typedef struct {
     bool viewport_size_dirty, viewport_updated_at_least_once;
     monotonic_t viewport_resized_at;
     LiveResizeInfo live_resize;
-    bool has_pending_resizes, is_semi_transparent, shown_once, is_damaged, has_cocoa_shadow, ignore_resize_events;
+    bool has_pending_resizes, is_semi_transparent, shown_once, is_damaged, ignore_resize_events;
     unsigned int clear_count;
     WindowChromeState last_window_chrome;
     float background_opacity;