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Thread: XY Coordinates

  1. #1

    Thread Starter
    New Member
    Join Date
    Dec 2017

    XY Coordinates

    Hi, I'm new to Visual Basic (since this week), and I have encountered my first problem...
    I'm trying to display a grid of pictures in a 6 by 7 pattern, so 6 rows, 7 columns :

    Dim TheGrid(6, 7) as PictureBox
    Dim Row as short
    Dim Col as short

    For Row = 1 To 6
    For Column = 1 To 7
    TheGrid(Row, Column) = New PictureBox
    TheGrid(Row, Column).Name = "Cell" + Trim(Str(Row)) + "_" + Trim(Str(Column))
    TheGrid(Row, Column).BackgroundImage = My.Resources.emptycell

    TheGrid(Row, Column).Location = New Point(10 + (50 * Row), 10 + (50 * Column))
    TheGrid(Row, Column).Size = New Size(40, 40)
    TheGrid(Row, Column).Visible = True
    TheGrid(Row, Column).Tag = 0

    Me.Controls.Add(TheGrid(Row, Column))

    Next Column
    Next Row

    Somehow, the result of my sourcecode is a 7 (rows) by 6 (columns) pattern...and I don't know why.
    I do have to specify the coordinates as X (row), Y (column) right..?
    I know VB starts array indexes from 0, but I'm starting at 1. But that can't be the problem.

    What am I doing wrong here?

  2. #2
    You don't want to know.
    Join Date
    Aug 2010

    Re: XY Coordinates

    Coordinates are goofy things, it's important to understand what each word means.

    On the monitor (and in Cartesian coordinates), the X axis is horizontal, with 0 at the left edge and increasing to the right. That means the X axis represents "columns".

    On the monitor the Y axis is vertical, with 0 at the top edge and increasing to the bottom. (This is inverted from standard Cartesian coordinates.) That means the Y axis represents "rows".

    You're treating rows as X coordinates and columns as Y coordinates, which will cause them to be transposed.

    In Visual Basic, arrays are defined by the upper bounds of their rank, not the size. So your (6, 7) array actually has 7 rows and 8 columns. You should define it as (5, 6), that's a 6 row, 7 column array.
    This answer is wrong. You should be using TableAdapter and Dictionaries instead.

  3. #3

    Thread Starter
    New Member
    Join Date
    Dec 2017

    Re: XY Coordinates

    Thanks a lot!
    I switched places for the Row and Column in the Location property and indeed...now it works...

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