Filter out corresponding modifiers from key events

Platforms differ here, but it's meaningless to ask about the state of a
modifier that's currently being pressed or released, so simply mask this out in
general so it's easy for platform implementations to clean events up before
dispatching them.

5 files changed, 38 insertions, 8 deletions

diff --git a/src/internal.c b/src/internal.c
index cff66be..b3ee86a 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -116,6 +116,29 @@ puglDecodeUTF8(const uint8_t* buf)
   return 0xFFFD;
 }
 
+PuglMods
+puglFilterMods(const PuglMods state, const PuglKey key)
+{
+  switch (key) {
+  case PUGL_KEY_SHIFT_L:
+  case PUGL_KEY_SHIFT_R:
+    return state & ~(PuglMods)PUGL_MOD_SHIFT;
+  case PUGL_KEY_CTRL_L:
+  case PUGL_KEY_CTRL_R:
+    return state & ~(PuglMods)PUGL_MOD_CTRL;
+  case PUGL_KEY_ALT_L:
+  case PUGL_KEY_ALT_R:
+    return state & ~(PuglMods)PUGL_MOD_ALT;
+  case PUGL_KEY_SUPER_L:
+  case PUGL_KEY_SUPER_R:
+    return state & ~(PuglMods)PUGL_MOD_SUPER;
+  default:
+    break;
+  };
+
+  return state;
+}
+
 PuglStatus
 puglPreRealize(PuglView* const view)
 {
diff --git a/src/internal.h b/src/internal.h
index 6c40dc2..3721c10 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -43,6 +43,10 @@ puglViewStringChanged(PuglView* view, PuglStringHint key, const char* value);
 uint32_t
 puglDecodeUTF8(const uint8_t* buf);
 
+/// Return `state` with any flags related to `key` removed
+PuglMods
+puglFilterMods(PuglMods state, PuglKey key);
+
 /// Prepare a view to be realized by the platform implementation if possible
 PuglStatus
 puglPreRealize(PuglView* view);
diff --git a/src/mac.m b/src/mac.m
index 07eb28d..ad1ef2b 100644
--- a/src/mac.m
+++ b/src/mac.m
@@ -679,7 +679,7 @@ handleCrossing(PuglWrapperView* view, NSEvent* event, const PuglEventType type)
     wloc.y,
     rloc.x,
     [[NSScreen mainScreen] frame].size.height - rloc.y,
-    getModifiers(event),
+    puglFilterMods(getModifiers(event), spec),
     [event keyCode],
     (code != 0xFFFD) ? code : 0,
   };
@@ -710,7 +710,7 @@ handleCrossing(PuglWrapperView* view, NSEvent* event, const PuglEventType type)
     wloc.y,
     rloc.x,
     [[NSScreen mainScreen] frame].size.height - rloc.y,
-    getModifiers(event),
+    puglFilterMods(getModifiers(event), spec),
     [event keyCode],
     (code != 0xFFFD) ? code : 0,
   };
@@ -868,7 +868,7 @@ handleCrossing(PuglWrapperView* view, NSEvent* event, const PuglEventType type)
                              wloc.y,
                              rloc.x,
                              [[NSScreen mainScreen] frame].size.height - rloc.y,
-                             mods,
+                             puglFilterMods(mods, special),
                              [event keyCode],
                              special};
 
diff --git a/src/win.c b/src/win.c
index 6838423..3d245f2 100644
--- a/src/win.c
+++ b/src/win.c
@@ -579,7 +579,8 @@ initKeyEvent(PuglKeyEvent* event,
 
   const PuglKey special = keySymToSpecial(vkey, ext);
   if (special) {
-    event->key = (uint32_t)special;
+    event->key   = (uint32_t)special;
+    event->state = puglFilterMods(event->state, special);
   } else if (!dead) {
     // Translate unshifted key
     BYTE    keyboardState[256] = PUGL_INIT_STRUCT;
diff --git a/src/x11.c b/src/x11.c
index e1e948f..ce0bf0b 100644
--- a/src/x11.c
+++ b/src/x11.c
@@ -888,10 +888,12 @@ translateKey(PuglView* const view, XEvent* const xevent, PuglEvent* const event)
   KeySym        sym     = 0;
   const int     ufound  = XLookupString(&xevent->xkey, ustr, 8, &sym, NULL);
   const PuglKey special = keySymToSpecial(sym);
-
-  event->key.key =
-    ((special || ufound <= 0) ? special
-                              : (PuglKey)puglDecodeUTF8((const uint8_t*)ustr));
+  if (special) {
+    event->key.state = puglFilterMods(event->key.state, special);
+    event->key.key   = special;
+  } else if (ufound > 0) {
+    event->key.key = (PuglKey)puglDecodeUTF8((const uint8_t*)ustr);
+  }
 
   if (xevent->type == KeyPress && !filter && !special && view->impl->xic) {
     // Lookup shifted key for possible text event