graphics/nxbe: Add some missing checks: Don't permit the software cursor to be enabled until it has been assigned an image; don't perform any cursor operations while the cursor is disabled.

graphics/nxbe/nxbe_bitmap.c

@@ -329,16 +329,21 @@ void nxbe_bitmap(FAR struct nxbe_window_s *wnd,
   nxbe_bitmap_dev(wnd, dest, src, origin, stride);
 
 #ifdef CONFIG_NX_SWCURSOR
-  /* Save the modified cursor background region
+  /* Update the software cursor if it is visible */
-   * REVISIT:  Only a single color plane is supported
-   */
 
-  wnd->be->plane[0].cursor.backup(wnd->be, dest, 0);
+  if (wnd->be->cursor.visible)
+    {
+      /* Save the modified cursor background region
+       * REVISIT:  Only a single color plane is supported
+       */
 
-  /* Restore the software cursor if any part of the cursor was
+      wnd->be->plane[0].cursor.backup(wnd->be, dest, 0);
-   * overwritten by the bitmap copy.
-   */
 
-  wnd->be->plane[0].cursor.draw(wnd->be, dest, 0);
+      /* Restore the software cursor if any part of the cursor was
+       * overwritten by the bitmap copy.
+       */
+
+      wnd->be->plane[0].cursor.draw(wnd->be, dest, 0);
+    }
 #endif
 }

graphics/nxbe/nxbe_cursor.c

@@ -69,23 +69,36 @@
 
 void nxbe_cursor_enable(FAR struct nxbe_state_s *be, bool enable)
 {
-  /* Are we enabling the cursor */
+  /* Are we enabling the cursor?  Don't allow the cursor to be enabled if no
+   * image has been assigned to the cursor  */
 
   if (enable && !be->cursor.visible)
     {
+#ifdef CONFIG_NX_SWCURSOR
+      /* Don't allow the cursor to be enabled if no image has been assigned
+       * to the cursor
+       */
+
+      if (be->cursor.image != NULL)
+        {
+          /* Save the cursor background image */
+
+          DEBUGASSERT(be->cursor.bkgd != NULL);
+          be->plane[0].cursor.backup(be, &be->cursor.bounds, 0);
+
+          /* Write the new cursor image to device memory */
+
+          be->plane[0].cursor.draw(be, &be->cursor.bounds, 0);
+
+          /* Mark the cursor visible */
+
+          be->cursor.visible = true;
+        }
+#else
       /* Mark the cursor visible */
 
       be->cursor.visible = true;
 
-#ifdef CONFIG_NX_SWCURSOR
-      /* Save the cursor background image */
-
-      be->plane[0].cursor.backup(be, &be->cursor.bounds, 0);
-
-      /* Write the new cursor image to device memory */
-
-      be->plane[0].cursor.draw(be, &be->cursor.bounds, 0);
-#else
       /* For a hardware cursor, this would require some interaction with the
        * grahics device.
        */
@@ -105,6 +118,7 @@ void nxbe_cursor_enable(FAR struct nxbe_state_s *be, bool enable)
 #ifdef CONFIG_NX_SWCURSOR
       /* Erase the old cursor image by writing the saved background image. */
 
+      DEBUGASSERT(be->cursor.bkgd != NULL);
       be->plane[0].cursor.erase(be, &be->cursor.bounds, 0);
 #else
       /* For a hardware cursor, this would require some interaction with the
@@ -156,6 +170,7 @@ void nxbe_cursor_setimage(FAR struct nxbe_state_s *be,
     {
       /* Erase the old cursor image by writing the saved background image. */
 
+      DEBUGASSERT(be->cursor.bkgd != NULL);
       be->plane[0].cursor.erase(be, &be->cursor.bounds, 0);
     }
 
@@ -283,16 +298,16 @@ void nxbe_cursor_setposition(FAR struct nxbe_state_s *be,
 
   nxgl_rectoffset(&be->cursor.bounds, &be->cursor.bounds, dx, dy);
 
-  /* Read in the new background image at this offset */
-
-  be->plane[0].cursor.backup(be, &be->cursor.bounds, 0);
-
   /* If the cursor is visible, then put write the new cursor image into
    * device graphics memory now.
    */
 
   if (be->cursor.visible)
     {
+      /* Read in the new background image at this offset */
+
+      be->plane[0].cursor.backup(be, &be->cursor.bounds, 0);
+
       /* Write the new cursor image to the device graphics memory. */
 
       be->plane[0].cursor.draw(be, &be->cursor.bounds, 0);

graphics/nxbe/nxbe_fill.c

@@ -129,21 +129,26 @@ static inline void nxbe_fill_dev(FAR struct nxbe_window_s *wnd,
                    &info.cops, &wnd->be->plane[i]);
 
 #ifdef CONFIG_NX_SWCURSOR
-      /* Save the modified cursor background region.
+      /* Update the software cursor if it is visible */
-       *
-       * REVISIT:  This and the following logic belongs in the function
-       * nxbe_clipfill().  It is here only because the struct nxbe_state_s
-       * (wnd->be) is not available at that point.  This may result in an
-       * excessive number of cursor updates.
-       */
 
-      wnd->be->plane[i].cursor.backup(wnd->be, rect, i);
+      if (wnd->be->cursor.visible)
+        {
+          /* Save the modified cursor background region.
+           *
+           * REVISIT:  This and the following logic belongs in the function
+           * nxbe_clipfill().  It is here only because the struct nxbe_state_s
+           * (wnd->be) is not available at that point.  This may result in an
+           * excessive number of cursor updates.
+           */
 
-      /* Restore the software cursor if any part of the cursor was
+          wnd->be->plane[i].cursor.backup(wnd->be, rect, i);
-       * overwritten by the fill.
-      */
 
-      wnd->be->plane[i].cursor.draw(wnd->be, rect, i);
+          /* Restore the software cursor if any part of the cursor was
+           * overwritten by the fill.
+          */
+
+          wnd->be->plane[i].cursor.draw(wnd->be, rect, i);
+        }
 #endif
     }
 }

graphics/nxbe/nxbe_filltrapezoid.c

@@ -159,21 +159,26 @@ static inline void nxbe_filltrapezoid_dev(FAR struct nxbe_window_s *wnd,
                    &info.cops, &wnd->be->plane[i]);
 
 #ifdef CONFIG_NX_SWCURSOR
-      /* Save the modified cursor background region.
+      /* Update the software cursor if it is visible */
-       *
-       * REVISIT:  This and the following logic belongs in the function
-       * nxbe_clipfilltrapezoid().  It is here only because the struct
-       * nxbe_state_s (wnd->be) is not available at that point.  This
-       * result in an excessive number of cursor updates.
-       */
 
-      wnd->be->plane[i].cursor.backup(wnd->be, bounds, i);
+      if (wnd->be->cursor.visible)
+        {
+          /* Save the modified cursor background region.
+           *
+           * REVISIT:  This and the following logic belongs in the function
+           * nxbe_clipfilltrapezoid().  It is here only because the struct
+           * nxbe_state_s (wnd->be) is not available at that point.  This
+           * result in an excessive number of cursor updates.
+           */
 
-      /* Restore the software cursor if any part of the cursor was
+          wnd->be->plane[i].cursor.backup(wnd->be, bounds, i);
-       * overwritten by the fill.
-      */
 
-      wnd->be->plane[i].cursor.draw(wnd->be, bounds, i);
+          /* Restore the software cursor if any part of the cursor was
+           * overwritten by the fill.
+           */
+
+          wnd->be->plane[i].cursor.draw(wnd->be, bounds, i);
+        }
 #endif
     }
 }

graphics/nxbe/nxbe_flush.c

@@ -95,11 +95,16 @@ void nxbe_flush(FAR struct nxbe_window_s *wnd,
   nxbe_bitmap_dev(wnd, dest, src, origin, stride);
 
 #ifdef CONFIG_NX_SWCURSOR
-  /* Restore the software cursor if any part of the cursor was overwritten
+  /* Is the software cursor visible? */
-   * by the above copy.
-   */
 
-  wnd->be->plane[0].cursor.draw(wnd->be, dest, 0);
+  if (wnd->be->cursor.visible)
+    {
+      /* Restore the software cursor if any part of the cursor was
+       * overwritten by the above copy.
+       */
+
+      wnd->be->plane[0].cursor.draw(wnd->be, dest, 0);
+    }
 #endif
 }
 

graphics/nxbe/nxbe_move.c

@@ -280,9 +280,14 @@ static inline void nxbe_move_dev(FAR struct nxbe_window_s *wnd,
 #endif
     {
 #ifdef CONFIG_NX_SWCURSOR
-      /* Remove the cursor from the source region */
+      /* Is the cursor visible? */
 
-      wnd->be->plane[i].cursor.erase(wnd->be, rect, i);
+      if (wnd->be->cursor.visible)
+        {
+          /* Remove the cursor from the source region */
+
+          wnd->be->plane[i].cursor.erase(wnd->be, rect, i);
+        }
 #endif
 
       nxbe_clipper(wnd->above, &info.srcrect, info.order,
@@ -290,23 +295,28 @@ static inline void nxbe_move_dev(FAR struct nxbe_window_s *wnd,
 
 
 #ifdef CONFIG_NX_SWCURSOR
-      /* Save the modified cursor background region at the destination
+      /* Update the software cursor if it is visible */
-       * region.  This would be necessary only for small moves that stay
-       * within the cursor region.
-       *
-       * REVISIT:  This and the following logic belongs in the function
-       * nxbe_clipmovedest().  It is here only because the struct
-       * nxbe_state_s (wnd->be) is not available at that point.  This
-       * result in an excessive number of cursor updates.
-       */
 
-      wnd->be->plane[i].cursor.backup(wnd->be, &dest, i);
+      if (wnd->be->cursor.visible)
+        {
+          /* Save the modified cursor background region at the destination
+           * region.  This would be necessary only for small moves that stay
+           * within the cursor region.
+           *
+           * REVISIT:  This and the following logic belongs in the function
+           * nxbe_clipmovedest().  It is here only because the struct
+           * nxbe_state_s (wnd->be) is not available at that point.  This
+           * result in an excessive number of cursor updates.
+           */
 
-      /* Restore the software cursor if any part of the cursor was
+          wnd->be->plane[i].cursor.backup(wnd->be, &dest, i);
-       * overwritten by the fill.
-      */
 
-      wnd->be->plane[i].cursor.draw(wnd->be, &dest, i);
+          /* Restore the software cursor if any part of the cursor was
+           * overwritten by the fill.
+           */
+
+          wnd->be->plane[i].cursor.draw(wnd->be, &dest, i);
+        }
 #endif
     }
 }

graphics/nxbe/nxbe_setpixel.c

@@ -153,20 +153,25 @@ void nxbe_setpixel(FAR struct nxbe_window_s *wnd,
                    &info.cops, &wnd->be->plane[i]);
 
 #ifdef CONFIG_NX_SWCURSOR
-      /* Save the modified cursor pixe at the point.
+      /* Update the software cursor if it is visible */
-       *
-       * REVISIT:  This and the following logic belongs in the function
-       * nxbe_clipfill().  It is here only because the struct nxbe_state_s
-       * (wnd->be) is not available at that point.
-       */
 
-      wnd->be->plane[i].cursor.backup(wnd->be, &rect, i);
+      if (wnd->be->cursor.visible)
+        {
+          /* Save the modified cursor pixe at the point.
+           *
+           * REVISIT:  This and the following logic belongs in the function
+           * nxbe_clipfill().  It is here only because the struct
+           * nxbe_state_s (wnd->be) is not available at that point.
+           */
 
-      /* Restore the software cursor if if that point is a visible cursor
+          wnd->be->plane[i].cursor.backup(wnd->be, &rect, i);
-       * bit that was overwritten by the above operation.
-       */
 
-      wnd->be->plane[i].cursor.draw(wnd->be, &rect, i);
+          /* Restore the software cursor if if that point is a visible
+           * cursor bit that was overwritten by the above operation.
+           */
+
+          wnd->be->plane[i].cursor.draw(wnd->be, &rect, i);
+        }
 #endif
     }
 }