C and Pascal handle booleans differently. In C they are basically integer values which are interpreted but in Pascal they form a special, separate type (or are at least treated as such).

So, what follows from this:

Macros which have a Boolean type result should be written as function with Pascal native Boolean type or cbool type depending on the further use of the macro.
SDL functions which have a SDL_Bool return value should be converted to return TSDL_Bool
SDL functions which need SDL_Bool value as argument will treat them correctly obviously
Pascal functions which rely on a TSDL_Bool value as argument should evaluate the integer values or typecast (see next point)
Attention: Typecast Boolean(TSDL_Bool) should be safe as TSDL_Bool can be 0 or 1 only, but in general care has to be taken with this cast, see http://www.delphigroups.info/2/10/12833.html
A logical expression can be returned into a TSDL_Bool value by typecasting, see example code below

program SDLBoolTest;

uses SDL2, ctypes, SysUtils;

var
  a, b: Integer;

function BoolTest(a, b: Integer): TSDL_Bool;
begin
  // works
  Result := TSDL_Bool(a > b);

  // does not work - Error: got "Boolean" expected "TSDL_Bool"
  //Result := (a > b);
end;

begin
  writeln('Bool Test a > b');
  for a:= 0 to 3 do
    for b := 0 to 3 do
      begin
        write('a = ' + IntToStr(a) + '; b = ' + IntToStr(b) +';    Result = ' + IntToStr(BoolTest(a, b)) + ' ');
        writeln(Boolean(BoolTest(a, b)));
      end;

  readln;
end.

So, for the example in the initial post it is correct to use the native Boolean, because a macro without a defined SDL_Bool return value should not adopt a fictional one.

Handle SDL_bool like a real boolean #30

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