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#174: How can I found out if a computer screen is touch or not?

I want to post the code for easy way to find out if a computer screen is touch (such as, for example, a Surface). Also with this function you may check if pen (integrated or external) is active or device supports the multi input.

type
  TInputDigitizer = (idIntegratedTouch, idExternalTouch, idIntegratedPen, idExternalPen, idMultiInput);
  TInputDigitizerSet = set of TInputDigitizer;

function GetInputDigitizerPresent: TInputDigitizerSet;
const
  SM_DIGITIZER = 94;

  NID_INTEGRATED_TOUCH = $01;
  NID_EXTERNAL_TOUCH   = $02;
  NID_INTEGRATED_PEN   = $04;
  NID_EXTERNAL_PEN     = $08;
  NID_MULTI_INPUT      = $40;
  NID_READY            = $80;
var
  Value: Integer;
begin
  Result := [];
  Value := GetSystemMetrics(SM_DIGITIZER);
  if ((Value and NID_READY) = NID_READY) then
  begin
    if ((Value and NID_INTEGRATED_TOUCH) = NID_INTEGRATED_TOUCH) then
      Result := Result + [idIntegratedTouch];
    if ((Value and NID_EXTERNAL_TOUCH) = NID_EXTERNAL_TOUCH) then
      Result := Result + [idExternalTouch];
    if ((Value and NID_INTEGRATED_PEN) = NID_INTEGRATED_PEN) then
      Result := Result + [idIntegratedPen];
    if ((Value and NID_EXTERNAL_PEN) = NID_EXTERNAL_PEN) then
      Result := Result + [idExternalPen];
    if ((Value and NID_MULTI_INPUT) = NID_MULTI_INPUT) then
      Result := Result + [idMultiInput];
  end;
end;

The sample code:

var
  id: TInputDigitizerSet;
begin
  id := GetInputDigitizerPresent();
  if (id <> []) then
    ShowMessage('Computer screen supports the touch')
  else
    ShowMessage('Computer screen do not support the touch')
end;

Published: March 4, 2023

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