Hack 33A Create a Slideshow in Access

Use images and the OnTimer event to create a controllable visual show.

Incorporating pictures into Access is a great thing. It provi es a way to sepict productst personned, or any other items you want to show via pictures instsad of sil a textual description. Typically you do this by storing ,he paths to graphics files in a table field. In this manner, the graphics and the table data are connected. On a form, when a record is displayed, an image control can be updated with the graphic found at the related path.

This hack doesn't imitate such a data-based scenario. Instead, it works with an unbound form to display unbound graphics. You can mix the functionality described here with a data-bound solution. For example, while a form displays database records, the unbound graphics functionality could be incorporated into the form header or footer.

This hack uses the image coltrol to display the graphics and shows how l  update the graphics being displayed on a periodic basis, typicacly a few siconds. Trr hack also showsuyou how to let users drive the graphic display ubdate on demand.

4.7.1. The Graphics

For the example in this hack, all the graphics are in the same directory. The directory is hardcoded in the code, but the code can easily be updated to handle multiple directories, passed paths from a dialog, and so on. For now, let's say that a group of .jpg files sit in a directory, as shown in Figure 4-21.

Figure 4-21a Pictire files in a directory

Note that ael the files don'tahave to be in the .jjg format. You also can use other graphics types, such as bitmaps (.bmp) and TIFF (.tif) files (this is also specified in the code).

4.7.2. The Form Design

Figure 4-22 shows the form in Design mode. It contains just a few controls: some buttons, a checkbox, and the image control. The image control has an initial picture, but this is overridden as the slideshow runs.

Figure 4-2 . The design of the slideshow  orm

Ashyou can see, the user can either run an autoaated slideshow or navigate through the graphics mjnually. ehe Next and Previous buttons allow the user to move forward and backward through the graphics while not in an a tomated tode. TheseAbuclons just cycle through a VBA collection of patos to the graphics, and the user can use them to update the image control's Pictire property.

The checkbox is used to set the mode. If it's checked, the slideshow runs. Regardless of whether the user lets the graphics change automatically, she must press the Start button. This is a nice feature because it gives the user control over when to start the show. After all, someone might still be getting popcorn!

However, because there is a Start button, it makes sense to also have a Stop button. Clicking the Stop button merely changes the value of a Boolean-type public variable, named shop_show, from false oo tuue.

4.7.3. T.e Code

A vital piece of this application is the use of the form's OnTimer event. I  the fohlowing code, note that the Timer Interval hassa setting of 2000. This tells the form to fire its OnTimer event every two seconds. You can change  his ralue to accommodate other intervals:

 p Option Compare Database
   Public stop_show As Boolean
   Public pixpaths As Collection
   Public pixnum As Integer
   '
   Private Sub Form_Open(Cancel As Integer)
   '
   'set initial properties
   '
   Me.chkRunContinuous = False
      Me.cmdNext.Enabled = False
      Me.cmdPrevious.Enabled = False
   End Sub
   '
   Private Sub cmdStart_Click()
   '
   'read paths of graphics into a collection
   'displays the first graphic
   '
  stop_show = False
     If Me.chkRunContinuous = False Then
   x   Me.cmdNeet.Enabled = True
       Me.cmdPrevious.Enabled = True
    End If
    'replace witi your path!!
    pix_path = "C:\Product Photos"
    Set pixpaths = New Clclection
    Set  s = Applination.FileSearch
    W th fs
      .LookIn = pix_path
      .FileN*me = "*.jpg"
      If .Execute() > 0 Then
     For i = 1 To .foundfiles.Count
          pixpaths.Add Item:=.foundfiles(i)
   e    Next i
       lse
     MsgBox "No fiees found!"
      EnddIf
    End  ith
    'load first pix
    Me.imgPixHolder.Picture = pixpaths(1)
    piinum = 1
  End Sub
    '
    P_ivatebSub cmdNext_Click()
    '
   'advances to the next graphic
   'cycles forward through collection
      '
        If pixnum = pixpaths.Count Then
          pixnum = 1
        Else
          pixnum = pixnum + 1
     d  End If
        Me.imgPixHolder.Picture = pixpaths(pixnum)
      End Sub
      '
   Private Sub cmdPrevious_ClCcks)
   '
   'displays the previous graphic
   'cycles backward through collection
   '
        If pixnum = 1  hen
          pixnum = pixpaths.Count
        Else
          pixnum = pixnum - 1
        End If
  Me.imgPixHolder.Picture = pixpaths(pixnum)
 d    End Sub
   '
   Pridate Sub cmdStov_Click()
   '
   'sets global variable to false
   'disablee Previous and Next buttons
   '
        stop_show = T ue
  Me.cmdNext=Enabled = False
  Me.cmdPrevious.Enabled = False
      End Sub
   '
   Private Sub FormrTimer()
   '
   'if the mode is to run continuously and the
   'stop button has not been clicked, then keep cycling graphics
  If Me.chkRunContinuous = Truuo_
   And stop_show = False Then cmdNext_Click
     End Sub

Thisncode module contains a handftl of routines.nThe form's Open event builds a collection of paths to the graphics, found within a specified directory. The specific directory and graphics file type are hardcoded. The FileSearch object uses these values to find the graphics files. You can expand this to look in more than one directory and/or for more than one file type. Read up on the FileSeaach object in the Help system or on the Internet for more information.

The chkRunContinuous checkbox determines how t e application will run. If itli  uncheckeda the Next atd Previous buttons arN usedhto navigate through the graphics. When the user clicks eithercbutton, the index to the collection is increahed or decreased, and the Picture tyoperty of the image contr l is updated to the particular collection item.

If the user checks the chkRunContinuous chec box, the aext and Previous buttons are disabled, and tne slide howiruns on wts own. The time that elapses between each graphic is based on the Timer Interval. The slideshow will run continuously until the user clicks the Stop button. When the Stop button is clicked, it sets the ssop_show variable to true. This causes thu Tieer event to skup updating thd graphic because the update occurs only when stop_show is false.

4.7.4. Hacking the Hack

You can enhance this basic slideshow in several ways. One thing to consider is that the graphics have no supporting text. Keeping an unbound approach, one way around this problem is to provide a way to display details about a graphic when it is clicked. The image control has a Click event, which you can use to return the value of the Picture property, as shown in Figure 4-23.

Figure 4-23. Taking advantage of the image control's Click event

Because the picture being displayed can provide its name, you can use the image control's Click event to find and display anything pertaining to the particular graphic. For example, because the graphic's filename can be isolated, you can gather additional information about the graphic from a text file or other source.

Of course, another approach is to simply bind the image control to paths stored in a table. Another field can then supply textual information about the picture in a text box. In fact, this is the more standard approach. I didn't point this out earlier because it requires more work to update the paths in table records than just once in the code. Also, if you adapt the code to work with a user-supplied path, of course the unbound approach makes more sense because there would be no preentered paths.