Jalaj

The Clipboard is a Virtual Area where an application can place some data which can be accessed by it later or by some other application. While complete control over clipboard requires using Windows API functions, Visual Basic provides a basic set of clipboard functions as methods to the Clipboard object.

The data that is copied to the Clipboard, or pasted from can be of several types are are predefined as contstants as under :

Const vbCFText = 1			' Plain Text
Const vbCFBitmap = 2			' Bitmap
Const vbCFMetafile = 3			' Metafile Picture Format
Const vbCFDIB = 8			' Device Independent Bitmap FOrmat
Const vbCFPalette = 9			' Color Palette
Const vbCFEMetafile = 14		' Enhanced Metafile Format
Const vbCFFiles = 15			' Files
Const vbCFLink = -16640 (&HFFFFBF00)	' Link
Const vbCFRTF = -16639 (&HFFFFBF01)	' Rich Text Format

More than one clipboard object can be placed on the keyboard, each in a different format, while representing the same information.

The four basic funtions that you will require most are

Clipboard.Clear() -
	Clears the current Clipboard contents

Clipboard.SetText(Str As String, [Format]) -
	Copies data to the clipboard (default being text,
	unless stated specifically using optional Format parameter)

Clipboard.GetFormat(Format as Integer)
	Returns True or False depending on whether Clipboard contained
	data in that partcular format

Clipboard.GetText([Format])
	Returns the data, Text if optional Format parameter not passed,
	from the Clipboard.

Similar commands to Set or Get picture data to / from Clipboard are :

Clipboard.SetData(Picture as IPictureDisp,[Format])

Clipboard.GetData([Format]) as IPictureDisp

The data that is passed / recieved above are IPictureDisp, which is the Interface to Picture Data.

Let’s make a sample application to get clear with the copy functions.

Create a new project place a Image control imgImage, multiline TextBox txtText and a command button cmdButton. Set the picture property of the Image to show image on the form. Add some string to the Textbox.

Add code as below to the Click event of the button

Private Sub cmdButton_Click()

    Clipboard.Clear
    Clipboard.SetText txtText
    Clipboard.SetData imgImage, vbCFBitmap

End Sub

The code above will clear the clipboard on press of the button. It will then place to the clipboard the text from the textBox and the image as Bitmap Format.

Now open the Wordpad and paste from the clipboard, and you will get the text pasted there. Click on “Paste Special…” from the menu and a dialog box will appear with three options one for the text, other for bitmap and yet another for Device Independant Bitmap. Selecting any of the last two will result in pasting of the image.

And a point to note here… the bitmap we pasted was of type Bitmap. But you also received option for device independant Bitmap. It is so for the reason that Windows Clipboard provides facility for conversion between related formats.