[PATCH] wlt_toolkit.c: Fix resize window stuck in need_resize=true

[Martin Minarik]

The problem is that:
 wnd->w_frame contains a number
and
 wnd->need_frame=true
Therefore schedule_frame() doesn't schedule the callback.
But deleting these checks causes flicker. Further redesign
of the frame sheduling was necessary.

4. frame_callback()
3. do_frame()
3. idle_frame()
2. schedule_frame()
1. wlt_window_set_size()

Please, observe the need_resize variable.
-------------------------------------------------------------------------------
BAD (window stuck on resize):
$3 = {ref = 1, list = {next = 0x659c70, prev = 0x659c70},
  buffer_attached = true, skip_damage = false, need_resize = true,
  w_frame = 0x70d9b0, widget_list = {next = 0x686cb0, prev = 0x6b54d0}}

OK (window not stuck on resize):
$3 = {ref = 1, list = {next = 0x240cc70, prev = 0x240cc70},
  buffer_attached = true, skip_damage = false, need_resize = false,
  w_frame = 0x241bb10, widget_list = {next = 0x2439cb0, prev = 0x2468560}}

-----------------------------------------------------------------------------------

This is the basic idea:

-> time ->
frame callbacks()      *           *           *           *           *           *
wnd->idle_pending ------   ---------   ---------    --------   ---------------------
wnd->need_frame   ---      --- ---     ---          ---        ------ ---
schedule_frame()  *        *   *       *            *          *  *   **
idle_frame()        *        *   *       *            *          *  *   *

This design follows similiar design in weston/clients/window.c

Kmscon                     Weston
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
wlt_window_do_redraw() ~~~ shm_surface_swap()
do_frame() ~~~~~~~~~~~~~~~ window_attach_surface()

wnd->idle_pending ~~~~~~~~ window->redraw_scheduled

frame_callback()  ~~~~~~~~ frame_callback()

do_frame()  ~~~~~~~~~~~~~~ idle_redraw()

wlt_window_set_size()
wlt_window_schedule_redraw()
schedule_frame()  ~~~~~~~~ window_schedule_redraw()
---
 src/wlt_toolkit.c |   34 ++++++++++++++--------------------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/src/wlt_toolkit.c b/src/wlt_toolkit.c
index 7ae6fdc..bdc1245 100644
--- a/src/wlt_toolkit.c
+++ b/src/wlt_toolkit.c
@@ -126,7 +126,6 @@ struct wlt_window {
 	bool buffer_attached;
 	bool skip_damage;
 	bool need_resize;
-	bool need_redraw;
 	bool need_frame;
 	bool idle_pending;
 	unsigned int new_width;
@@ -1305,7 +1304,7 @@ static void wlt_window_do_redraw(struct wlt_window *wnd,
 }
 
 static int resize_window(struct wlt_window *wnd, unsigned int width,
-			 unsigned int height, bool force_redraw)
+			 unsigned int height)
 {
 	struct shl_dlist *iter;
 	struct wlt_widget *widget;
@@ -1351,8 +1350,7 @@ static int resize_window(struct wlt_window *wnd, unsigned int width,
 
 	if (width == wnd->buffer.width &&
 	    height == wnd->buffer.height) {
-		if (force_redraw)
-			wlt_window_do_redraw(wnd, width, height);
+		wlt_window_do_redraw(wnd, width, height);
 		return 0;
 	}
 
@@ -1420,25 +1418,17 @@ static const struct wl_callback_listener frame_callback_listener = {
 
 static void do_frame(struct wlt_window *wnd)
 {
-	bool force;
-
-	wnd->idle_pending = false;
 	ev_eloop_unregister_idle_cb(wnd->disp->eloop, idle_frame, wnd);
 
 	if (wnd->need_resize) {
-		force = wnd->need_redraw;
 		wnd->need_frame = true;
 		wnd->need_resize = false;
-		wnd->need_redraw = false;
 		wnd->w_frame = wl_surface_frame(wnd->w_surface);
 		wl_callback_add_listener(wnd->w_frame,
 					 &frame_callback_listener, wnd);
-		resize_window(wnd, wnd->new_width, wnd->new_height, force);
-	}
-
-	if (wnd->need_redraw) {
+		resize_window(wnd, wnd->new_width, wnd->new_height);
+	} else {
 		wnd->need_frame = true;
-		wnd->need_redraw = false;
 		wnd->w_frame = wl_surface_frame(wnd->w_surface);
 		wl_callback_add_listener(wnd->w_frame,
 					 &frame_callback_listener, wnd);
@@ -1447,6 +1437,8 @@ static void do_frame(struct wlt_window *wnd)
 	}
 }
 
+static void schedule_frame(struct wlt_window *wnd);
+
 static void frame_callback(void *data, struct wl_callback *w_callback,
 			   uint32_t time)
 {
@@ -1454,9 +1446,10 @@ static void frame_callback(void *data, struct wl_callback *w_callback,
 
 	wl_callback_destroy(w_callback);
 	wnd->w_frame = NULL;
-	wnd->need_frame = false;
 
-	do_frame(wnd);
+	wnd->idle_pending = false;
+	if (wnd->need_frame)
+		schedule_frame(wnd);
 }
 
 static void idle_frame(struct ev_eloop *eloop, void *unused, void *data)
@@ -1495,10 +1488,12 @@ static void schedule_frame(struct wlt_window *wnd)
 {
 	int ret;
 
-	if (!wnd || wnd->w_frame)
+	if (!wnd)
 		return;
 
-	if (wnd->need_frame || wnd->idle_pending)
+	wnd->need_frame = true;
+
+	if (wnd->idle_pending)
 		return;
 
 	ret = ev_eloop_register_idle_cb(wnd->disp->eloop, idle_frame, wnd);
@@ -1590,7 +1585,7 @@ int wlt_display_create_window(struct wlt_display *disp,
 				      &shell_surface_listener, wnd);
 	wl_shell_surface_set_toplevel(wnd->w_shell_surface);
 
-	ret = resize_window(wnd, width, height, true);
+	ret = resize_window(wnd, width, height);
 	if (ret)
 		goto err_shell_surface;
 
@@ -1674,7 +1669,6 @@ void wlt_window_schedule_redraw(struct wlt_window *wnd)
 	if (!wnd)
 		return;
 
-	wnd->need_redraw = true;
 	schedule_frame(wnd);
 }
 
-- 
1.7.10.4