input: fix handling of MP_KEY_STATE_DOWN

VOs can use the MP_KEY_STATE_DOWN modifier to pass key up/down events to
input.c, instead of just simple key presses. This allows doing key auto-
repeat handling in input.c, if the VO doesn't want to do that.

One issue is that so far, this code has been used only for mouse events,
even though the code was originally written with keyboard keys in mind.
One difference between mouse keys and keyboard keys is that the initial
key down should not generate an input command with mouse buttons
(input.c did that), while keyboard events should (input.c didn't do
that). Likewise, releasing a key should generate input commands for
mouse buttons releases, but not for the keyboard.

Change the code so mouse buttons (recognized via the MP_NO_REPEAT_KEY
flag) follow the old hehavior, while other keys generate input commands
on key down, but not on key release.

Note that a key release event is posted either using
MP_INPUT_RELEASE_ALL, or a normal key press event after having sent a an
event with MP_KEY_STATE_DOWN. This is probably a bit confusing, and a
MP_KEY_STATE_RELEASE should be added.

Fix shift-handling with MP_KEY_STATE_DOWN as well.

2 files changed, 16 insertions, 6 deletions

diff --git a/core/input/input.c b/core/input/input.c
index 1790834a53..c36b357fbb 100644
--- a/core/input/input.c
+++ b/core/input/input.c
@@ -1186,7 +1186,7 @@ static mp_cmd_t *interpret_key(struct input_ctx *ictx, int code)
      * we want to have "a" and "A" instead of "a" and "Shift+A"; but a separate
      * shift modifier is still kept for special keys like arrow keys.
      */
-    int unmod = code & ~MP_KEY_MODIFIER_MASK;
+    int unmod = code & ~(MP_KEY_MODIFIER_MASK | MP_KEY_STATE_DOWN);
     if (unmod >= 32 && unmod < MP_KEY_BASE)
         code &= ~MP_KEY_MODIFIER_SHIFT;
 
@@ -1208,7 +1208,10 @@ static mp_cmd_t *interpret_key(struct input_ctx *ictx, int code)
         ictx->num_key_down++;
         ictx->last_key_down = GetTimer();
         ictx->ar_state = 0;
-        return NULL;
+        ret = NULL;
+        if (!(code & MP_NO_REPEAT_KEY))
+            ret = get_cmd_from_keys(ictx, ictx->num_key_down, ictx->key_down);
+        return ret;
     }
     // button released or press of key with no separate down/up events
     for (j = 0; j < ictx->num_key_down; j++) {
@@ -1224,6 +1227,7 @@ static mp_cmd_t *interpret_key(struct input_ctx *ictx, int code)
         j = ictx->num_key_down - 1;
         ictx->key_down[j] = code;
     }
+    bool emit_key = ictx->last_key_down && (code & MP_NO_REPEAT_KEY);
     if (j == ictx->num_key_down) {  // was not already down; add temporarily
         if (ictx->num_key_down > MP_MAX_KEY_DOWN) {
             mp_tmsg(MSGT_INPUT, MSGL_ERR, "Too many key down events "
@@ -1232,12 +1236,12 @@ static mp_cmd_t *interpret_key(struct input_ctx *ictx, int code)
         }
         ictx->key_down[ictx->num_key_down] = code;
         ictx->num_key_down++;
-        ictx->last_key_down = 1;
+        emit_key = true;
     }
     // Interpret only maximal point of multibutton event
-    ret = ictx->last_key_down ?
-          get_cmd_from_keys(ictx, ictx->num_key_down, ictx->key_down)
-          : NULL;
+    ret = NULL;
+    if (emit_key)
+        ret = get_cmd_from_keys(ictx, ictx->num_key_down, ictx->key_down);
     if (doubleclick) {
         ictx->key_down[j] = code - MP_MOUSE_BTN0_DBL + MP_MOUSE_BTN0;
         return ret;
@@ -1288,11 +1292,13 @@ void mp_input_feed_key(struct input_ctx *ictx, int code)
 {
     ictx->got_new_events = true;
     if (code == MP_INPUT_RELEASE_ALL) {
+        mp_msg(MSGT_INPUT, MSGL_V, "input: release all\n");
         memset(ictx->key_down, 0, sizeof(ictx->key_down));
         ictx->num_key_down = 0;
         ictx->last_key_down = 0;
         return;
     }
+    mp_msg(MSGT_INPUT, MSGL_V, "input: key code=%#x\n", code);
     struct mp_cmd *cmd = interpret_key(ictx, code);
     if (!cmd)
         return;
diff --git a/core/input/keycodes.h b/core/input/keycodes.h
index 14f7b9ee85..2e0e5fd33f 100644
--- a/core/input/keycodes.h
+++ b/core/input/keycodes.h
@@ -186,8 +186,12 @@
                               MP_KEY_MODIFIER_ALT | MP_KEY_MODIFIER_META)
 
 // Use this when the key shouldn't be auto-repeated (like mouse buttons)
+// This is not a modifier, but is part of the keycode itself.
 #define MP_NO_REPEAT_KEY (1<<28)
 
+// Flag for key events. Multiple down events are idempotent. Release keys by
+// sending the key code without this flag, or by sending MP_INPUT_RELEASE_ALL
+// as key code.
 #define MP_KEY_STATE_DOWN (1<<29)
 
 #endif /* MPLAYER_KEYCODES_H */