VB3 How to Size a Picture Box Dynamically to Fit an AVI Image

- Microsoft Visual Basic for Windows, version 3.0

SUMMARY

To size a picture box to fit an AVI image at run time, you must first get the dimensions of the AVI file. This article shows you how to do it.

MORE INFORMATION

The example uses the mciSendCommand function to get the dimensions of the AVI file currently referenced by an MCI control.

Step-by-Step Example Demonstrates How to Get the Dimensions of an AVI file

1. Start a new project in Visual Basic. Add a module (.BAS) file, and make sure the MCI control is included in the project. Add a MCI control (MMControl1), a Command Button (Command1), and a Picture box (Picture1) to Form1. Set Form1's ScaleMode property to Pixels (3).

2. In the General declarations section of the .BAS file, add this code:

   Type RECT

         left As Integer
         top As Integer
         right As Integer
         bottom As Integer
   

   End Type

   Type MCI_OVLY_RECT_PARMS

         dwCallback As Long
         rc As RECT
   

   End Type

   Global Const MCI_OVLY_WHERE_SOURCE = &H20000 Global Const MCI_OVLY_WHERE_DESTINATION = &H40000 Global Const MCI_WHERE = &H843

      ' Enter the following Declare statement on one, single line:
      Declare Function mciSendCommand Lib "mmsystem" (ByVal udeviceid As
         Integer, ByVal uMessage As Integer, ByVal dwParam1 As Long, dwParam2
         As Any) As Long
   
      ' Enter the following Declare statement on one, single line:
      Declare Function mciGetErrorString Lib "mmsystem" (ByVal wError As
         Long, ByVal lpstrBuffer As String, ByVal uLength As Integer) As
         Integer
   
   

3. In the Command1_Click() method for the command button on Form1, enter this code:

      Sub Command1_Click ()
         Const MB_OK = 0
         Const MB_ICONSTOP = 16
   
         Dim Retval&, Buffer$
         Dim dwParam2 As MCI_OVLY_RECT_PARMS
   
         MMControl1.Command = "Close"
         MMControl1.Filename = "WndSurf1.avi"  ' Sample AVI file to be played.
   
         ' Get the MCI control to display the video in Picture1:
         MMControl1.hWndDisplay = Picture1.hWnd
   
         MMControl1.Command = "Open"
   
         ' Initialize the structure being passed with mciSendCommand, and
         ' set it in case you want to use the Notify property:
         dwParam2.dwCallback = MMControl1.hWnd
         dwParam2.rc.left = 0
         dwParam2.rc.top = 0
         dwParam2.rc.right = 0
         dwParam2.rc.bottom = 0
   
         ' Send the message:
         ' Enter the following two lines as one, single line of code:
         Retval& = mciSendCommand(MMControl1.DeviceID, MCI_WHERE,
            MCI_OVLY_WHERE_SOURCE, dwParam2)
   
         If Retval& <> 0 Then  ' An error occurred.
            Buffer$ = Space$(100)
            ' Get a description of the error:
            Retval& = mciGetErrorString(Retval&, Buffer$, Len(Buffer$))
            MsgBox Trim$(Buffer$), MB_OK + MB_ICONSTOP, "ERROR"
         Else
            ' Resize the picture box:
            Picture1.Width = dwParam2.rc.right - dwParam2.rc.left
            Picture1.Height = dwParam2.rc.bottom - dwParam2.rc.top
   
            ' Play the video:
            MMControl1.Wait = True ' Wait for the next command to complete
            MMControl1.Command = "play" 'Play the video clip
            MMControl1.Command = "close"
         End If
      End Sub
   
   

4. Test the program. Press F5 to run it, and click the command button. The AVI file will play back in the picture box, which will have been resized to fit the video clip exactly.