How to Distinguish a DblClick from a Click Event

• Microsoft Visual Basic Standard and Professional Editions for Windows, versions 1.0, 2.0, 3.0

SUMMARY

Usually when you issue two consecutive mouse clicks on a form or object, you will receive a click event for the first mouse click and another click event or a double-click event for the second mouse click -- depending on the period of time between the mouse clicks.

At times, you may want to receive only the double-click event without the preceding click event. This article describes how to write code to accomplish this.

MORE INFORMATION

The following example demonstrates how to receive only a DblClick event on a form rather than a Click and then a DblClick event.

Step-by-Step Example

1. Start a new project in Visual Basic. Form1 is created by default.



2. Add a Timer control (Timer1) to Form1.



3. Add the following code to the (general) (declarations) section of Form1:

   
      ' The following Function gets the DoubleClickSpeed from the WIN.INI
      ' file. Windows uses this setting to determine how close together two
      ' consecutive mouse clicks must occur for it to be interpreted as
      ' a double-click.
      ' Enter the following Declare statement on one, single line:
      Declare Function GetProfileInt% Lib "Kernel" (ByVal lpAppName$,
         ByVal lpKeyName$, ByVal nDefault%) 




4. Add the following code to the specified event procedures:

   
      Sub Form_Load ()
         clickSpeed% = GetProfileInt("Windows", "DoubleClickSpeed", 0)
         Timer1.Enabled = False         ' Timer should be off to begin with.
         Timer1.Interval = clickSpeed%  ' After the timer is turned on
                                        ' it will trigger the Timer Event
                                        ' after a specific amount of time
                                        ' equal to that of DoubleClickSpeed.
      End Sub
   
      Sub Form_Click ()
         Timer1.Enabled = True          ' Turn the timer on. If another mouse
                                        ' click does not occur within the
                                        ' DoubleClickSpeed interval, the
                                        ' Timer1_Timer Event will fire.
      End Sub
   
      Sub Form_DblClick ()
         Timer1.Enabled = False         ' Turn off the timer. This
                                        ' prevents the Timer1_Timer event
                                        ' from firing and thus the code
                                        ' for a single click will not be
                                        ' processed.
         Print "This is a double-click" ' Code for double-click goes here.
      End Sub
   
      Sub Timer1_Timer ()
         ' If this event occurs then there has not been another mouse
         ' click since the previous one within the DoubleClickSpeed
         ' time interval. Thus there will be two Click events rather
         ' than a DblClick Event.
         Timer1.Enabled = False         ' Turn off the timer so the
                                        ' Timer1_Timer Event does not
                                        ' continue to fire.
         Print "This is a Single Click" ' Code for single click goes here.
      End Sub 




5. Run the program.



6. Click once, wait a while, click again to receive two single clicks.



7. Click twice quickly to receive a double-click with no preceding single click.

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