sub: simplify OSD redrawing logic

Normally, we can redraw the OSD any time. But some drivers don't support
OSD redrawing (vo_null etc.), or only "sometimes" (vo_xv). For that,
some additional logic is needed. Simplify that logic. This might also
fix subtle bugs with the OSD not updating or endless frame stepping in
unforseen corner cases.

Do this by adding a new flag, which tells whether the OSD should be
redrawn.

Remove some minor code duplication.

3 files changed, 16 insertions, 25 deletions

diff --git a/mplayer.c b/mplayer.c
index 0edd8bfc1c..f9b6f687c1 100644
--- a/mplayer.c
+++ b/mplayer.c
@@ -2544,15 +2544,22 @@ void unpause_player(struct MPContext *mpctx)
     (void)get_relative_time(mpctx);     // ignore time that passed during pause
 }
 
+static void draw_osd(struct MPContext *mpctx)
+{
+    struct vo *vo = mpctx->video_out;
+
+    mpctx->osd->vo_pts = mpctx->video_pts;
+    vo_draw_osd(vo, mpctx->osd);
+    mpctx->osd->want_redraw = false;
+}
+
 static int redraw_osd(struct MPContext *mpctx)
 {
     struct vo *vo = mpctx->video_out;
     if (vo_redraw_frame(vo) < 0)
         return -1;
 
-    mpctx->osd->vo_pts = mpctx->video_pts;
-    vo_draw_osd(vo, mpctx->osd);
-    osd_reset_changed(mpctx->osd);
+    draw_osd(mpctx);
 
     vo_flip_page(vo, 0, -1);
     return 0;
@@ -3158,10 +3165,7 @@ static void run_playloop(struct MPContext *mpctx)
         mpctx->video_pts = sh_video->pts;
         update_subtitles(mpctx, sh_video->pts);
         update_osd_msg(mpctx);
-
-        mpctx->osd->vo_pts = mpctx->video_pts;
-        vo_draw_osd(vo, mpctx->osd);
-        osd_reset_changed(mpctx->osd);
+        draw_osd(mpctx);
 
         mpctx->time_frame -= get_relative_time(mpctx);
         mpctx->time_frame -= vo->flip_queue_offset;
@@ -3303,7 +3307,8 @@ static void run_playloop(struct MPContext *mpctx)
         if (sleeptime > 0) {
             if (!mpctx->sh_video)
                 goto novideo;
-            if (osd_has_changed(mpctx->osd) || mpctx->video_out->want_redraw) {
+            if (mpctx->osd->want_redraw || mpctx->video_out->want_redraw) {
+                mpctx->osd->want_redraw = false;
                 if (redraw_osd(mpctx) < 0) {
                     if (mpctx->paused && video_left)
                         add_step_frame(mpctx);
diff --git a/sub/sub.c b/sub/sub.c
index 5a39fbdf60..8281081334 100644
--- a/sub/sub.c
+++ b/sub/sub.c
@@ -280,21 +280,7 @@ void vo_osd_changed(int new_value)
         if (osd->objs[n]->type == new_value)
             osd->objs[n]->force_redraw = true;
     }
-}
-
-bool osd_has_changed(struct osd_state *osd)
-{
-    for (int n = 0; n < MAX_OSD_PARTS; n++) {
-        if (osd->objs[n]->force_redraw)
-            return true;
-    }
-    return false;
-}
-
-void osd_reset_changed(struct osd_state *osd)
-{
-    for (int n = 0; n < MAX_OSD_PARTS; n++)
-        osd->objs[n]->force_redraw = false;
+    osd->want_redraw = true;
 }
 
 bool sub_bitmaps_bb(struct sub_bitmaps *imgs, int *x1, int *y1,
diff --git a/sub/sub.h b/sub/sub.h
index 3ac160a323..88a49a2906 100644
--- a/sub/sub.h
+++ b/sub/sub.h
@@ -126,6 +126,8 @@ struct osd_state {
 
     bool render_subs_in_filter;
 
+    bool want_redraw;
+
     char *osd_text;             // OSDTYPE_OSD
     int progbar_type, progbar_value; // OSDTYPE_PROGBAR
 
@@ -203,8 +205,6 @@ extern int sub_justify;
 struct osd_state *osd_create(struct MPOpts *opts, struct ass_library *asslib);
 void osd_set_text(struct osd_state *osd, const char *text);
 void vo_osd_changed(int new_value);
-void osd_reset_changed(struct osd_state *osd);
-bool osd_has_changed(struct osd_state *osd);
 void osd_free(struct osd_state *osd);
 
 enum mp_osd_draw_flags {