Time for action – generating new pieces

1. Add the GenerateNewPieces() method to the GameBoard class:

   Public Sub GenerateNewPieces(dropSquare As Boolean)
     Dim x, y As Integer
   
     If dropSquare Then
       For x = 0 To GameBoardWidth
         For y = GameBoardHeight To 0 Step -1
           If GetSquare(x, y) = "Empty" Then
             FillFromAbove(x, y)
           End If
         Next
       Next
     End If
   
     For y = 0 To GameBoardHeight
       For x = 0 To GameBoardWidth
         If GetSquare(x, y) = "Empty" Then
           RandomPiece(x, y)
         End If
       Next
     Next
   
   End Sub

What just happened?

When GenerateNewPieces() is called with true passed as dropSquares, the looping logic processes one column at a time from the bottom up. By using the step 1 in the for loop for the Y coordinate, we can make the loop run backwards instead of the default forward direction. When it finds an empty square, it calls FillFromAbove() to pull a filled square from above into that location.

The reason the processing order is important here...