From 21d586cc86e8d700289175e4873c53cfb591c026 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 12 Sep 2018 10:44:24 +0530
Subject: [PATCH] macOS: Fix resizing semi-transparent windows causing the
 windows to be invisible during the resize

Fixes #941
Workaround for  https://github.com/glfw/glfw/issues/1251
---
 docs/changelog.rst |  2 ++
 kitty/glfw.c       | 11 +++++++++++
 kitty/shaders.c    | 13 +++++++++----
 kitty/state.h      |  1 +
 4 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 478d8a319..bde7fb038 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -43,6 +43,8 @@ Changelog
 - Fix kitty @set-colors not working for tab backgrounds when using the `fade` tabbar style
   (:iss:`937`)
 
+- macOS: Fix resizing semi-transparent windows causing the windows to be
+  invisible during the resize (:iss:`941`)
 
 0.12.1 [2018-09-08]
 ------------------------------
diff --git a/kitty/glfw.c b/kitty/glfw.c
index e24fef8b2..6a32b817c 100644
--- a/kitty/glfw.c
+++ b/kitty/glfw.c
@@ -106,6 +106,17 @@ framebuffer_size_callback(GLFWwindow *w, int width, int height) {
         window->has_pending_resizes = true; global_state.has_pending_resizes = true;
         window->last_resize_event_at = monotonic();
         unjam_event_loop();
+#ifdef __APPLE__
+        // Cocoa starts a sub-loop inside wait events which means main_loop
+        // stays stuck and no rendering happens. This causes the window to be
+        // blank. This is particularly bad for semi-transparent windows since
+        // they are rendered as invisible, so for that case we manually render.
+        if (global_state.callback_os_window->is_semi_transparent) {
+            make_os_window_context_current(global_state.callback_os_window);
+            blank_os_window(global_state.callback_os_window);
+            swap_window_buffers(global_state.callback_os_window);
+        }
+#endif
     } else log_error("Ignoring resize request for tiny size: %dx%d", width, height);
     global_state.callback_os_window = NULL;
 }
diff --git a/kitty/shaders.c b/kitty/shaders.c
index 5c630aed3..1f3f1c1c3 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -426,15 +426,20 @@ set_cell_uniforms(float current_inactive_text_alpha) {
     }
 }
 
+void
+blank_os_window(OSWindow *os_window) {
+#define C(shift) (((GLfloat)((OPT(background) >> shift) & 0xFF)) / 255.0f)
+        glClearColor(C(16), C(8), C(0), os_window->is_semi_transparent ? os_window->background_opacity : 1.0f);
+#undef C
+        glClear(GL_COLOR_BUFFER_BIT);
+}
+
 bool
 send_cell_data_to_gpu(ssize_t vao_idx, ssize_t gvao_idx, GLfloat xstart, GLfloat ystart, GLfloat dx, GLfloat dy, Screen *screen, OSWindow *os_window) {
     bool changed = false;
     if (os_window->clear_count < 2) {
         os_window->clear_count++;
-#define C(shift) (((GLfloat)((OPT(background) >> shift) & 0xFF)) / 255.0f)
-        glClearColor(C(16), C(8), C(0), os_window->is_semi_transparent ? os_window->background_opacity : 1.0f);
-#undef C
-        glClear(GL_COLOR_BUFFER_BIT);
+        blank_os_window(os_window);
         changed = true;
     }
     if (os_window->fonts_data) {
diff --git a/kitty/state.h b/kitty/state.h
index 1e83315b6..7ca18771a 100644
--- a/kitty/state.h
+++ b/kitty/state.h
@@ -189,6 +189,7 @@ void update_surface_size(int, int, uint32_t);
 void free_texture(uint32_t*);
 void send_image_to_gpu(uint32_t*, const void*, int32_t, int32_t, bool, bool);
 void send_sprite_to_gpu(FONTS_DATA_HANDLE fg, unsigned int, unsigned int, unsigned int, pixel*);
+void blank_os_window(OSWindow *);
 void set_titlebar_color(OSWindow *w, color_type color);
 FONTS_DATA_HANDLE load_fonts_data(double, double, double);
 void send_prerendered_sprites_for_window(OSWindow *w);