Q141072: How To Size a Picture Box Dynamically to Fit an AVI Image

Article: Q141072
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.00
Operating System(s): 
Keyword(s): kbcode kbWndw
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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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 demonstrates 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
--------------------

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 Long
        Top As Long
        Right As Long
        Bottom As Long
     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:

     Declare Function mciSendCommand Lib "winmm.dll" _
        Alias "mciSendCommandA" ( _
           ByVal wDeviceID As Long, _
           ByVal uMessage As Long, _
           ByVal dwParam1 As Long,
           dwParam2 As Any) As Long

     ' Enter the following Declare statement:
     Declare Function mciGetErrorString Lib "winmm.dll" _
        Alias "mciGetErrorStringA" ( _
           ByVal dwError As Long, _
           ByVal lpstrBuffer As String, _
           ByVal uLength As Long) As Long

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 by pressing the F5 key to run it, and clicking the command
  button. The AVI file will play back in the picture box, which will have been
  resized to fit the video clip exactly.

Additional query words: 3.00 4.00 MCI AVI vb4win vb432

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Keywords          : kbcode kbWndw 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400
Version           : 4.00

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