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Graphical Mouse Application In Visual Basic 6

The mouse events can be combined with graphics methods and any number of customized drawing or paint applications can be created. The following application combines MouseMove and MouseDown events, and illustrates a drawing program.

Open a new Standard EXE project and save the Form as Draw.frm and save the Project as Draw.vbp. Name the caption of the as Drawing. Add command button control and name the caption of it as Clear

Enter the following code in the Form_MouseDown ( ) procedure, Form_MouseMove ( ) procedure and cmdClear_Click ( ) procedures respectively.

Private Sub cmdClear_Click()
End Sub

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
frmDraw.CurrentX = X
frmDraw.CurrentY = Y
End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = 1 Then
Line (frmDraw.CurrentX, frmDraw.CurrentY)-(X, Y)
End If
End Sub

Button value 1 indicates that the left mouse button is clicked. The code written in the MouseDown event changes the CurrentX and CurrentY to the coordinates where the mouse button was just clicked.

Run the application. You can notice that when the mouse is clicked and moved in the Form a line is drawn corresponding to the mouse movement. Following figure illustrates the combined action of MouseDown and MouseMove.

Graphical Mouse Application

The program uses two graphics related Visual Basic concepts, the Line method and the CurrentX and CurrentY properties. Line method is preferred to draw a line in a Form. The following statement draws a line from the coordinates X = 2500, Y = 2000, X = 5000, Y = 5500

Line (2500, 2000) - (5000, 5500)

The CurrentX and CurrentY properties are not visible in the properties window of the Form because it cannot be set at the design time. After using the Line method to draw a line in a Form, Visual Basic automatically assigns the coordinate of the line's end point to the CurrentX and CurrentY properties of the Form on which the line is drawn.

( Download the source code )

MouseMove application

Visual Basic does not generate a MouseMove event for every pixel the mouse moves over and a limited number of mouse messages are generated per second by the operating environment. The following application illustrates how often the Form_MouseMove ( ) event is executed.

Open a new standard EXE project and save the form as MouseMove.frm and save the Project as MouseMOve.vbp. Place a CommandButton control and name the caption as Clear and set the name as cmdClear.

The following code is entered in the cmdClear_Click ( ) and Form_MouseMove ( ) events respectively.

Private Sub cmdClear_Click()
End Sub

Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
Circle (X, Y), 70
End Sub

The above procedure simply draws small circles at the mouse's current location using the Circle method. The parameter x, y represent the centre of the circle, and the second parameter represents the radius of the circle.

Save the application and run. You can notice that when the mouse is moved inside the Form, circles are drwan along the path of the mouse movement as shown in below figure. And also you can notice the circles are widely spaced when the mouse is moved quickly. Each small circle is an indication that the MouseMove event occured and the Form_MouseMove ( ) procedure was executed.

MouseMove Application

( Download the source code )


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