fixes showing OnDiskBitmap with adafruit_sdcard

Author: FoamyGuy

shared-module/displayio/Display.c

@@ -317,11 +317,10 @@ STATIC bool _refresh_area(displayio_display_obj_t* self, const displayio_area_t*
 }
 
 STATIC void _refresh_display(displayio_display_obj_t* self) {
-    if (!displayio_display_core_bus_free(&self->core)) {
-        // Can't acquire display bus; skip updating this display. Try next display.
+    if (!displayio_display_core_start_refresh(&self->core)) {
+        // A refresh on this bus is already in progress.  Try next display.
         return;
     }
-    displayio_display_core_start_refresh(&self->core);
     const displayio_area_t* current_area = _get_refresh_areas(self);
     while (current_area != NULL) {
         _refresh_area(self, current_area);

shared-module/displayio/display_core.c

@@ -295,8 +295,17 @@ void displayio_display_core_set_region_to_update(displayio_display_core_t* self,
     }
 }
 
-void displayio_display_core_start_refresh(displayio_display_core_t* self) {
+bool displayio_display_core_start_refresh(displayio_display_core_t* self) {
+    if (!displayio_display_core_bus_free(self)) {
+        // Can't acquire display bus; skip updating this display. Try next display.
+        return false;
+    }
+    if (self->refresh_in_progress) {
+        return false;
+    }
+    self->refresh_in_progress = true;
     self->last_refresh = supervisor_ticks_ms64();
+    return true;
 }
 
 void displayio_display_core_finish_refresh(displayio_display_core_t* self) {
@@ -305,6 +314,7 @@ void displayio_display_core_finish_refresh(displayio_display_core_t* self) {
         displayio_group_finish_refresh(self->current_group);
     }
     self->full_refresh = false;
+    self->refresh_in_progress = false;
     self->last_refresh = supervisor_ticks_ms64();
 }
 

shared-module/displayio/display_core.h

@@ -54,6 +54,7 @@ typedef struct {
     int16_t colstart;
     int16_t rowstart;
     bool full_refresh; // New group means we need to refresh the whole display.
+    bool refresh_in_progress;
 } displayio_display_core_t;
 
 void displayio_display_core_construct(displayio_display_core_t* self,
@@ -78,7 +79,7 @@ void displayio_display_core_set_region_to_update(displayio_display_core_t* self,
 
 void release_display_core(displayio_display_core_t* self);
 
-void displayio_display_core_start_refresh(displayio_display_core_t* self);
+bool displayio_display_core_start_refresh(displayio_display_core_t* self);
 void displayio_display_core_finish_refresh(displayio_display_core_t* self);
 
 void displayio_display_core_collect_ptrs(displayio_display_core_t* self);