Problem:        How To Use OnPenDown/OnPenUp Scripts to Detect Pen Taps on Controls

Solution:        This article describes a technique using a global PenTapInControl script in conjunction with OnPenDown/OnPenUp form scripts to detect when controls are tapped on, for use on controls that do not have an OnClick method (such as edit controls, text labels, lookups, bitmaps, etc).

Let's assume that you want to detect pen taps in a control in a manner consistent with the standard controls that support OnClick events; that is, a valid "click" is when the user taps the pen down on the control, and then lifts the pen up while still on the control.  Tapping down on a control, then sliding off the control and lifting the pen when not on the control does not count as a valid click.

This can be accomplished using a combination of global functions, global variables, and OnPenDown/OnPenUp scripts on a given form.

First the global vars that we need in order to track pen tap coordinates across multiple scripts:

'pen tracking global vars

Dim gOPDX, gOPDY, gOPUX, gOPUY

[For those curious about the variable naming convention, they are named after Global OnPenDown X, Global OnPenDown Y, Global OnPenUp X, Global OnPenUp Y.]

Next the OnPenDown script on a form:

'record the pen down but don't track it around the form

'save x/y coords to global vars for use in other scripts

'note these save to the "D" or "Down" global vars

GetPenStatus(gOPDX, gOPDY)

Next the OnPenUp script.  This example tracks taps for two controls, Edit1

and Edit2.

'record the pen up position but don't track it around the form

'save x/y coords to global vars for use in other scripts

'note these save to the "U" or "Up" global vars

GetPenStatus(gOPUX, gOPUY)

Dim cX, cY, cW, cH

'test if pen tapped within bounds of Edit1 control

Edit1.GetPosition(cX, cY, cW, cH)

If PenTapInControl(cX, cY, cW, cH) then

msgbox("You tapped inside Edit1")

Exit 'leave the script

Endif

'test if pen tapped within bounds of Edit2 control

Edit2.GetPosition(cX, cY, cW, cH)

If PenTapInControl(cX, cY, cW, cH) then

msgbox("You tapped inside Edit2")

Exit 'leave the script

Endif

Okay, so you can see that the OnPenUp event script calls a global function named PenTapInControl, passing it the coordinates of the control that you want to test the pen taps for.   Remember that we consider it a tap ONLY if the pen taps down on the form and also lifts up from the form within the bounds of a given control.  A user can tap down then slide away and lift off outside of a control and that is not considered a tap (just like the standard UI behaviour for controls).  That PenTapInControl global function looks like this:

'check supplied coordinates against stored global PenUp and PenDown coords

'return True if pen tapped (down and up) in control or False if not

Function PenTapInControl( cX, cY, cW, cH )

Dim dDX, dDY, dUX, dUY

dDX = gOPDX - cX 'pen down x coordinate differential

dUX = gOPUX - cX 'pen up x coordinate differential

dDY = gOPDY - cY 'pen down y coordinate differential

dUY = gOPUY - cY 'pen up y coordinate differential

'verify that pen differentials lie within width and height of control

If ( (dDX <= cW) and (dDX >= 0) and _

   (dUX <= cW) and (dUX >= 0) and _

    (dDY <= cH) and (dDY >= 0) and _

    (dUY <= cH) and (dUY >= 0) ) then

  PenTapInControl = True

else

  PenTapInControl = False

Endif

End Function

That should do it.  You can then expand it to other controls by adding additional PenTapInControl tests in the OnPenUp script.

Keywords:        PenTapInControl, OnPenDown, OnPenUp, pen, tap, click, global, GetPosition, GetPenStatus

KB ID: 10059 

Updated: 2007-06-22

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