Tutorial 18 - Displaying Arbitrary Bitmaps

In this tutorial, you will learn how to use Style objects to display arbitrary bitmaps within list cells. In addition to font, color, and alignment settings, Style objects support both background and foreground pictures. Background pictures can be centered, tiled, or stretched to fill the entire cell. Foreground pictures can be positioned relative to the cell text, and can also be displayed using a transparent color.

Start a new project.
Place a True DBList control (TDBList1), a command button (Command1), and a TextBox control (Text1) on the form (Form1).
Set the DataMode property of TDBList1 to 4 - Storage (the default value of this property is 0 - Bound).
Right-click TDBList1 to display its context menu and choose Properties to display the Property Pages dialog box.
Click on the RowHeight property on the General Properties page, and enter the desired row height.
Select the Columns property page by clicking the Columns tab. Set the Caption property of Columns(00) and Columns(01) to Picture and File Name, respectively.
Select the Style Factory property page by clicking the Style Factory tab. Expand the Normal style and change its VerticalAlignment property from 0 - Top to 2 - Vertical Center. This will ensure that the text and pictures are vertically centered in each row.
Set the Caption (Visual Basic) property of Command1 to Display. Your form should now look like this:

Adding XArrayDB to the project

As in Tutorial 19, we will use the XArrayDB object; therefore, we need to add its reference to the project.
Select References from the Project menu to display a list of available type library references. Select the check box labeled ComponentOne XArrayDB Object (XARRAYDB.OCX), and then press the OK button.
Enter the path of the \Bitmaps\Flags directory in the Text property of Text1.

Add the following declaration to the General section of Form1:

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Dim x As New XArrayDB

Enter the following code in the Form_Load (Visual Basic) event:

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Private Sub Form_Load() ' Initially we resize the XArrayDB ' to 0 rows and 2 columns x.ReDim 0, -1, 0, 1 Set TDBList1.Array = x ' Enable FetchCellStyle Event TDBList1.Columns(0).FetchStyle = True End Sub

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Private Sub Form_Load()

' Initially we resize the XArrayDB

' to 0 rows and 2 columns

    x.ReDim 0, -1, 0, 1

    Set TDBList1.Array = x

   

' Enable FetchCellStyle Event

    TDBList1.Columns(0).FetchStyle = True

End Sub

Add the following code to the Click (Visual Basic) event of Command1:

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Private Sub Command1_Click() Dim s As String Dim i As Integer x.ReDim 0, -1, 0, 1 i = 0 ' Fill the XArrayDB object with all bitmap ' file names found in this directory s = Dir(Text1.Text & "\*.bmp") While s <> "" If s <> "." And s <> ".." Then x.ReDim 0, x.UpperBound(1) + 1, 0, 1 x(i, 1) = s i = i + 1 End If s = Dir Wend ' Reinitialize the list TDBList1.Bookmark = Null TDBList1.ReBind End Sub

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Private Sub Command1_Click()

    Dim s As String

    Dim i As Integer

   

    x.ReDim 0, -1, 0, 1

  

    i = 0

   

' Fill the XArrayDB object with all bitmap

' file names found in this directory

    s = Dir(Text1.Text & "\*.bmp")

   

    While s <> ""

        If s <> "." And s <> ".." Then

            x.ReDim 0, x.UpperBound(1) + 1, 0, 1

            x(i, 1) = s

            i = i + 1

        End If

        s = Dir

    Wend

   

' Reinitialize the list

    TDBList1.Bookmark = Null

    TDBList1.ReBind

End Sub

Enter the following code in the FetchCellStyle event:

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Private Sub TDBList1_FetchCellStyle( _ ByVal Condition As Integer, ByVal Split As Integer, _ Bookmark As Variant, ByVal Col As Integer, _ ByVal CellStyle As TrueDBList80.StyleDisp) Dim PathFileName As String ' Full Path file name of a picture PathFileName = Text1.Text & "\" & _ TDBList1.Columns(1).CellText(Bookmark) ' Load the picture CellStyle.BackgroundPicture = LoadPicture(PathFileName) End Sub

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Private Sub TDBList1_FetchCellStyle( _

    ByVal Condition As Integer, ByVal Split As Integer, _

    Bookmark As Variant, ByVal Col As Integer, _

    ByVal CellStyle As TrueDBList80.StyleDisp)

 

    Dim PathFileName As String

' Full Path file name of a picture

    PathFileName = Text1.Text & "\" & _

                   TDBList1.Columns(1).CellText(Bookmark)

 

' Load the picture

    CellStyle.BackgroundPicture = LoadPicture(PathFileName)

End Sub

Run the program and observe the following:

True DBList is initially displayed with no rows. In the text box, type the name of a directory containing bitmap files (with a .bmp extension), then press the Display button. The list will display pictures in the first column and their filenames in the second.
You have created a fully functional bitmap browser with just a few lines of code.

For more information, see Applying Pictures to List Elements.

This concludes Tutorial 18.