When drawing a POI over the map center, alternate

Draw the map center symbol for 1s, then the POI symbol for 1s.
This feels more natural than not drawing the POI when both are
very close, since flying over the home location would make the
craft disappear from the map.

src/main/io/osd.c

@@ -107,7 +107,7 @@
 // Adjust OSD_MESSAGE's default position when
 // changing OSD_MESSAGE_LENGTH
 #define OSD_MESSAGE_LENGTH 28
-#define OSD_ALTERNATING_TEXT(ms, num_choices) ((millis() / ms) % num_choices)
+#define OSD_ALTERNATING_CHOICES(ms, num_choices) ((millis() / ms) % num_choices)
 #define _CONST_STR_SIZE(s) ((sizeof(s)/sizeof(s[0]))-1) // -1 to avoid counting final '\0'
 // Wrap all string constants intenteded for display as messages with
 // this macro to ensure compile time length validation.
@@ -934,7 +934,7 @@ static void osdDrawMap(int referenceHeading, uint8_t referenceSym, uint8_t cente
             break;
     }
 
-    if (STATE(GPS_FIX) && poiDistance > scale) {
+    if (STATE(GPS_FIX)) {
 
         int directionToPoi = osdGetHeadingAngle(poiDirection + referenceHeading);
         float poiAngle = DEGREES_TO_RADIANS(directionToPoi);
@@ -958,18 +958,21 @@ static void osdDrawMap(int referenceHeading, uint8_t referenceSym, uint8_t cente
                 continue;
             }
 
-            if (poiX == midX && poiY == midY && centerSym != SYM_BLANK) {
+            if (poiX == midX && poiY == midY) {
                 // We're over the map center symbol, so we would be drawing
-                // over it even if we increased the scale. No reason to run
-                // this loop 50 times.
-                break;
-            }
+                // over it even if we increased the scale. Alternate between
+                // drawing the center symbol or drawing the POI.
+                if (centerSym != SYM_BLANK && OSD_ALTERNATING_CHOICES(1000, 2) == 0) {
+                    break;
+                }
+            } else {
 
-            uint8_t c;
-            if (displayReadCharWithAttr(osdDisplayPort, poiY, poiY, &c, NULL) && c != SYM_BLANK) {
-                // Something else written here, increase scale. If the display doesn't support reading
-                // back characters, we assume there's nothing.
-                continue;
+                uint8_t c;
+                if (displayReadCharWithAttr(osdDisplayPort, poiY, poiY, &c, NULL) && c != SYM_BLANK) {
+                    // Something else written here, increase scale. If the display doesn't support reading
+                    // back characters, we assume there's nothing.
+                    continue;
+                }
             }
 
             // Draw the point on the map
@@ -1590,7 +1593,7 @@ static bool osdDrawSingleElement(uint8_t item)
                         messages[messageCount++] = navStateFSMessage;
                     }
                     if (messageCount > 0) {
-                        message = messages[OSD_ALTERNATING_TEXT(1000, messageCount)];
+                        message = messages[OSD_ALTERNATING_CHOICES(1000, messageCount)];
                         if (message == failsafeInfoMessage) {
                             // failsafeInfoMessage is not useful for recovering
                             // a lost model, but might help avoiding a crash.
@@ -1630,12 +1633,12 @@ static bool osdDrawSingleElement(uint8_t item)
                     // Pick one of the available messages. Each message lasts
                     // a second.
                     if (messageCount > 0) {
-                        message = messages[OSD_ALTERNATING_TEXT(1000, messageCount)];
+                        message = messages[OSD_ALTERNATING_CHOICES(1000, messageCount)];
                     }
                 }
             } else if (ARMING_FLAG(ARMING_DISABLED_ALL_FLAGS)) {
                 // Check if we're unable to arm for some reason
-                if (OSD_ALTERNATING_TEXT(1000, 2) == 0) {
+                if (OSD_ALTERNATING_CHOICES(1000, 2) == 0) {
                     message = "UNABLE TO ARM";
                     TEXT_ATTRIBUTES_ADD_INVERTED(elemAttr);
                 } else {