win: split struct win

Currently compton handles window creation event by immediately query all
the information it needs and create a window struct with that
information. However, this is prone to race conditions.

In the future, we want to react to window creation event by creating a
placeholder in the window stack, and only query window information in a
critical section where the X server is grabbed by us.

This commit split struct win into two struct, one as placeholder, the
other for holding actual window information.

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

src/backend/backend.c

@@ -50,7 +50,7 @@ region_t get_damage(session_t *ps, bool all_damage) {
 }
 
 /// paint all windows
-void paint_all_new(session_t *ps, win *const t, bool ignore_damage) {
+void paint_all_new(session_t *ps, struct managed_win *t, bool ignore_damage) {
 	// All painting will be limited to the damage, if _some_ of
 	// the paints bleed out of the damage region, it will destroy
 	// part of the image we want to reuse
@@ -98,7 +98,7 @@ void paint_all_new(session_t *ps, win *const t, bool ignore_damage) {
 	// on top of that window. This is used to reduce the number of pixels painted.
 	//
 	// Whether this is beneficial is to be determined XXX
-	for (win *w = t; w; w = w->prev_trans) {
+	for (auto w = t; w; w = w->prev_trans) {
 		pixman_region32_subtract(&reg_visible, &ps->screen_reg, w->reg_ignore);
 		assert(!(w->flags & WIN_FLAGS_IMAGE_ERROR));
 

src/backend/backend.h

@@ -11,7 +11,7 @@
 #include "x.h"
 
 typedef struct session session_t;
-typedef struct win win;
+struct managed_win;
 
 struct backend_operations;
 
@@ -48,7 +48,7 @@ struct backend_operations {
 	///    1) if ps->overlay is not XCB_NONE, use that
 	///    2) use ps->root otherwise
 	/// TODO make the target window a parameter
-	backend_t *(*init)(session_t *) attr_nonnull(1);
+	backend_t *(*init)(session_t *)attr_nonnull(1);
 	void (*deinit)(backend_t *backend_data) attr_nonnull(1);
 
 	/// Called when rendering will be stopped for an unknown amount of
@@ -92,7 +92,7 @@ struct backend_operations {
 
 	/// Fill rectangle of target, mostly for debug purposes, optional.
 	void (*fill)(backend_t *backend_data, double r, double g, double b, double a,
-		     const region_t *clip);
+	             const region_t *clip);
 
 	/// Blur a given region of the target.
 	bool (*blur)(backend_t *backend_data, double opacity, const region_t *reg_blur,
@@ -129,8 +129,7 @@ struct backend_operations {
 	//     want to break that assumption as for now. We need to reconsider this.
 
 	/// Free resources associated with an image data structure
-	void (*release_image)(backend_t *backend_data, void *img_data)
-	    attr_nonnull(1, 2);
+	void (*release_image)(backend_t *backend_data, void *img_data) attr_nonnull(1, 2);
 
 	// ===========        Query         ===========
 
@@ -179,12 +178,11 @@ struct backend_operations {
 	/// Let the backend hook into the event handling queue
 };
 
-typedef backend_t *(*backend_init_fn)(session_t *ps) attr_nonnull(1);
+typedef backend_t *(*backend_init_fn)(session_t *ps)attr_nonnull(1);
 
 extern struct backend_operations *backend_list[];
 
-bool default_is_win_transparent(void *, win *, void *);
-bool default_is_frame_transparent(void *, win *, void *);
-void paint_all_new(session_t *ps, win *const t, bool ignore_damage) attr_nonnull(1);
+void paint_all_new(session_t *ps, struct managed_win *const t, bool ignore_damage)
+    attr_nonnull(1);
 
 // vim: set noet sw=8 ts=8 :

src/backend/backend_common.c

@@ -279,11 +279,3 @@ default_backend_render_shadow(backend_t *backend_data, int width, int height,
 	xcb_render_free_picture(backend_data->c, pict);
 	return ret;
 }
-
-bool default_is_win_transparent(void *backend_data, win *w, void *win_data) {
-	return w->mode != WMODE_SOLID;
-}
-
-bool default_is_frame_transparent(void *backend_data, win *w, void *win_data) {
-	return w->frame_opacity != 1;
-}