Window state tracking refactor

Window state tracking is basically the back bond of window fading. We
add a new enum field to the win struct to track the state of the window,
instead of using a set of boolean variables. We also remove the fading
callbacks, since it is only used for fading, so the potential of code
reuse is lost. And it makes the code slightly harder to understand.

Also fixed a problem that --no-fading-openclose is not behaving as
advertised (from my observation, enabling this flag disables fading
entirely, instead of just diabling it for open/close).

Also uses double for opacity everywhere internally. Use opacity_t only
when setting X opacity prop.

TODO: Remove win::*_last

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/win.h

@@ -64,6 +64,46 @@ typedef enum {
   WMODE_SOLID, // The window is opaque including the frame
 } winmode_t;
 
+/// Transition table:
+/// (DESTROYED is when the win struct is destroyed and freed)
+/// ('o' means in all other cases)
+/// (Window is created in the UNMAPPED state)
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |             |UNMAPPING|DESTROYING|MAPPING|FADING |UNMAPPED| MAPPED |DESTROYED|
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |  UNMAPPING  |    o    |  Window  |Window |  -    | Fading |  -     |    -    |
+/// |             |         |destroyed |mapped |       |finished|        |         |
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |  DESTROYING |    -    |    o     |   -   |  -    |   -    |  -     | Fading  |
+/// |             |         |          |       |       |        |        |finished |
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |   MAPPING   | Window  |  Window  |   o   |  -    |   -    | Fading |    -    |
+/// |             |unmapped |destroyed |       |       |        |finished|         |
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |    FADING   | Window  |  Window  |   -   |  o    |   -    | Fading |    -    |
+/// |             |unmapped |destroyed |       |       |        |finished|         |
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |   UNMAPPED  |    -    |    -     |Window |  -    |   o    |   -    | Window  |
+/// |             |         |          |mapped |       |        |        |destroyed|
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+/// |    MAPPED   | Window  |  Window  |   -   |Opacity|   -    |   o    |    -    |
+/// |             |unmapped |destroyed |       |change |        |        |         |
+/// +-------------+---------+----------+-------+-------+--------+--------+---------+
+typedef enum {
+  // The window is being faded out because it's unmapped.
+  WSTATE_UNMAPPING,
+  // The window is being faded out because it's destroyed,
+  WSTATE_DESTROYING,
+  // The window is being faded in
+  WSTATE_MAPPING,
+  // Window opacity is not at the target level
+  WSTATE_FADING,
+  // The window is mapped, no fading is in progress.
+  WSTATE_MAPPED,
+  // The window is unmapped, no fading is in progress.
+  WSTATE_UNMAPPED,
+} winstate_t;
+
 /**
  * About coordinate systems
  *
@@ -88,6 +128,9 @@ struct win {
   // Core members
   /// ID of the top-level frame window.
   xcb_window_t id;
+  /// The "mapped state" of this window, doesn't necessary
+  /// match X mapped state, because of fading.
+  winstate_t state;
   /// Window attributes.
   xcb_get_window_attributes_reply_t a;
   xcb_get_geometry_reply_t g;
@@ -175,20 +218,12 @@ struct win {
   char *class_general;
   /// <code>WM_WINDOW_ROLE</code> value of the window.
   char *role;
-  const c2_lptr_t *cache_sblst;
-  const c2_lptr_t *cache_fblst;
-  const c2_lptr_t *cache_fcblst;
-  const c2_lptr_t *cache_ivclst;
-  const c2_lptr_t *cache_bbblst;
-  const c2_lptr_t *cache_oparule;
-  const c2_lptr_t *cache_pblst;
-  const c2_lptr_t *cache_uipblst;
 
   // Opacity-related members
   /// Current window opacity.
-  opacity_t opacity;
+  double opacity;
   /// Target window opacity.
-  opacity_t opacity_tgt;
+  double opacity_tgt;
   /// true if window (or client window, for broken window managers
   /// not transferring client window's _NET_WM_OPACITY value) has opacity prop
   bool has_opacity_prop;
@@ -197,18 +232,11 @@ struct win {
   /// true if opacity is set by some rules
   bool opacity_is_set;
   /// Last window opacity value we set.
-  opacity_t opacity_set;
+  double opacity_set;
 
   // Fading-related members
-  /// Do not fade if it's false. Change on window type change.
-  /// Used by fading blacklist in the future.
-  bool fade;
-  /// Fade state on last paint.
-  bool fade_last;
   /// Override value of window fade state. Set by D-Bus method calls.
   switch_t fade_force;
-  /// Callback to be called after fading completed.
-  void (*fade_callback) (session_t *ps, win **w);
 
   // Frame-opacity-related members
   /// Current window frame opacity. Affected by window opacity.
@@ -269,7 +297,7 @@ void win_determine_mode(session_t *ps, win *w);
  * Set real focused state of a window.
  */
 void win_set_focused(session_t *ps, win *w, bool focused);
-void win_determine_fade(session_t *ps, win *w);
+bool attr_const win_should_fade(session_t *ps, const win *w);
 void win_update_prop_shadow_raw(session_t *ps, win *w);
 void win_update_prop_shadow(session_t *ps, win *w);
 void win_set_shadow(session_t *ps, win *w, bool shadow_new);
@@ -288,8 +316,11 @@ void win_unmark_client(session_t *ps, win *w);
 void win_recheck_client(session_t *ps, win *w);
 xcb_window_t win_get_leader_raw(session_t *ps, win *w, int recursions);
 bool win_get_class(session_t *ps, win *w);
-void win_calc_opacity(session_t *ps, win *w);
-void win_calc_dim(session_t *ps, win *w);
+double attr_const win_get_opacity_target(session_t *ps, const win *w);
+bool attr_const win_should_dim(session_t *ps, const win *w);
+void win_update_screen(session_t *, win *);
+/// Prepare window for fading because opacity target changed
+void win_start_fade(session_t *, win **);
 /**
  * Reread opacity property of a window.
  */
@@ -336,18 +367,8 @@ region_t win_get_region_noframe_local_by_val(win *w);
 void
 win_update_frame_extents(session_t *ps, win *w, xcb_window_t client);
 bool add_win(session_t *ps, xcb_window_t id, xcb_window_t prev);
-
-/**
- * Set fade callback of a window, and possibly execute the previous
- * callback.
- *
- * If a callback can cause rendering result to change, it should call
- * `queue_redraw`.
- *
- * @param exec_callback whether the previous callback is to be executed
- */
-void win_set_fade_callback(session_t *ps, win **_w,
-    void (*callback) (session_t *ps, win **w), bool exec_callback);
+/// Unmap or destroy a window
+void unmap_win(session_t *ps, win **, bool destroy);
 
 /**
  * Execute fade callback of a window if fading finished.
@@ -369,11 +390,14 @@ win_get_leader(session_t *ps, win *w) {
 }
 
 /// check if window has ARGB visual
-bool win_has_alpha(win *w);
+bool attr_const win_has_alpha(const win *w);
 
 /// check if reg_ignore_valid is true for all windows above us
 bool win_is_region_ignore_valid(session_t *ps, win *w);
 
+/// Free all resources in a struct win
+void free_win_res(session_t *ps, win *w);
+
 static inline region_t
 win_get_bounding_shape_global_by_val(win *w) {
   region_t ret;