Provide Ample Target Space

The pen often proves an inaccurate pointing device. The well-behaved pen application allows ample margin for pointing errors from the user, who can easily miss a small button or other target. Consider the following suggestions to make your pen-based application friendly to the user with poor aim:

  • Create targets as large as practical.

  • Space toolbar buttons so that they have gaps between them.

  • Avoid crowding dialog boxes with controls placed near one another.

  • Pen-down events falling within a few pixels of a button should be treated as a press of that button. Always increase the effective size of a control by sending the HE_SETINFLATE submessage, as described in the "HE_SETINFLATE Submessage" section in Chapter 3, "The Writing Process."

  • Compensate for the pixel sizes of different displays. Use GetDeviceCaps to determine sizes and maintain uniform dimensions for on-screen targets.

Software for developers
Delphi Components
.Net Components
Software for Android Developers
More information resources
Unix Manual Pages
Delphi Examples