SDL3-m2/showcases/showcase_debug_text.mod

MODULE showcase_debug_text ;

(*
   m2SDL3 showcase, ported from SDL upstream
   examples/renderer/18-debug-text/debug-text.c (public domain).

   Renders built-in bitmap debug text: plain lines, a colored line,
   a 4x-scaled line and a live "running for N seconds" counter.

   Porting notes
   - SDL_RenderDebugTextFormat (C varargs) has no Modula-2 mapping,
     so the counter line is composed into a CHAR buffer with the
     local AppendCard helper instead.
   - The upstream emoji line is ASCII-only in SDL anyway; the emoji
     bytes are replaced by plain words here (CHAR literals stay
     8-bit clean this way).
   - Callback structure flattened into a main loop; auto-quit
     after 8 s so the showcase also terminates unattended.
*)

FROM SYSTEM IMPORT CARDINAL8;
FROM SDL3 IMPORT SDL_Init, SDL_Quit, SDL_Delay,
   SDL_GetTicks, SDLInitVideo;
FROM SDL3Video IMPORT WindowHandle, SDL_DestroyWindow, WindowResizable;
FROM SDL3Render IMPORT RendererHandle,
   SDL_CreateWindowAndRenderer, SDL_DestroyRenderer,
   SDL_SetRenderDrawColor, SDL_RenderClear, SDL_RenderPresent,
   SDL_SetRenderLogicalPresentation, LogicalLetterbox,
   SDL_SetRenderScale, SDL_RenderDebugText;
FROM SDL3Utils IMPORT DrainEvents;
FROM libc IMPORT printf;

CONST FrameMs = 16; MaxMs = 8000;
CONST WinW = 640; WinH = 480;

VAR
   win: WindowHandle;
   ren: RendererHandle;
   quit: BOOLEAN;
   start: LONGCARD;
   secs: LONGCARD;
   pos: CARDINAL;
   msg: ARRAY [0..127] OF CHAR;

(* Append decimal n at buf[pos]; RETURN new pos (buf stays NUL-ended). *)
PROCEDURE AppendCard (VAR buf: ARRAY OF CHAR; pos: CARDINAL;
                      n: LONGCARD) : CARDINAL;
VAR digits: ARRAY [0..23] OF CHAR; nd, k: CARDINAL;
BEGIN
   nd := 0;
   IF n = 0 THEN digits[0] := "0"; nd := 1
   ELSE
      WHILE n > 0 DO
         digits[nd] := CHR(ORD("0") + VAL(CARDINAL, n MOD 10));
         INC(nd);
         n := n DIV 10
      END
   END;
   k := nd;
   WHILE k > 0 DO
      DEC(k);
      IF pos <= HIGH(buf) THEN buf[pos] := digits[k]; INC(pos) END
   END;
   IF pos <= HIGH(buf) THEN buf[pos] := 0C END;
   RETURN pos
END AppendCard;

PROCEDURE AppendStr (VAR buf: ARRAY OF CHAR; pos: CARDINAL;
                     s: ARRAY OF CHAR) : CARDINAL;
VAR k: CARDINAL;
BEGIN
   k := 0;
   WHILE (k <= HIGH(s)) AND (s[k] # 0C) DO
      IF pos <= HIGH(buf) THEN buf[pos] := s[k]; INC(pos) END;
      INC(k)
   END;
   IF pos <= HIGH(buf) THEN buf[pos] := 0C END;
   RETURN pos
END AppendStr;

BEGIN
   IF NOT SDL_Init(SDLInitVideo) THEN
      printf("showcase_debug_text: SDL_Init failed\n");
      HALT(1)
   END;
   IF NOT SDL_CreateWindowAndRenderer("m2SDL3 debug text",
                                      WinW, WinH,
                                      VAL(LONGCARD, WindowResizable),
                                      win, ren) THEN
      printf("showcase_debug_text: CreateWindowAndRenderer failed\n");
      SDL_Quit;
      HALT(1)
   END;
   SDL_SetRenderLogicalPresentation(ren, WinW, WinH, LogicalLetterbox);

   printf("showcase_debug_text: close window or wait 8s\n");
   quit := FALSE;
   start := SDL_GetTicks();
   WHILE NOT quit DO
      DrainEvents(quit);

      SDL_SetRenderDrawColor(ren, VAL(CARDINAL8, 0), VAL(CARDINAL8, 0),
                             VAL(CARDINAL8, 0), VAL(CARDINAL8, 255));
      SDL_RenderClear(ren);

      SDL_SetRenderDrawColor(ren, VAL(CARDINAL8, 255), VAL(CARDINAL8, 255),
                             VAL(CARDINAL8, 255), VAL(CARDINAL8, 255));
      SDL_RenderDebugText(ren, VAL(SHORTREAL, 272.0),
                          VAL(SHORTREAL, 100.0), "Hello world!");
      SDL_RenderDebugText(ren, VAL(SHORTREAL, 224.0),
                          VAL(SHORTREAL, 150.0),
                          "This is some debug text.");

      SDL_SetRenderDrawColor(ren, VAL(CARDINAL8, 51), VAL(CARDINAL8, 102),
                             VAL(CARDINAL8, 255), VAL(CARDINAL8, 255));
      SDL_RenderDebugText(ren, VAL(SHORTREAL, 184.0),
                          VAL(SHORTREAL, 200.0),
                          "You can do it in different colors.");
      SDL_SetRenderDrawColor(ren, VAL(CARDINAL8, 255), VAL(CARDINAL8, 255),
                             VAL(CARDINAL8, 255), VAL(CARDINAL8, 255));

      SDL_SetRenderScale(ren, VAL(SHORTREAL, 4.0), VAL(SHORTREAL, 4.0));
      SDL_RenderDebugText(ren, VAL(SHORTREAL, 14.0),
                          VAL(SHORTREAL, 65.0), "It can be scaled.");
      SDL_SetRenderScale(ren, VAL(SHORTREAL, 1.0), VAL(SHORTREAL, 1.0));
      SDL_RenderDebugText(ren, VAL(SHORTREAL, 64.0),
                          VAL(SHORTREAL, 350.0),
                          "This only does ASCII chars.");

      secs := (SDL_GetTicks() - start) DIV 1000;
      pos := AppendStr(msg, 0, "(This program has been running for ");
      pos := AppendCard(msg, pos, secs);
      pos := AppendStr(msg, pos, " seconds.)");
      SDL_RenderDebugText(ren, VAL(SHORTREAL, 136.0),
                          VAL(SHORTREAL, 400.0), msg);

      SDL_RenderPresent(ren);
      IF SDL_GetTicks() - start > MaxMs THEN quit := TRUE END;
      SDL_Delay(FrameMs)
   END;

   SDL_DestroyRenderer(ren);
   SDL_DestroyWindow(win);
   SDL_Quit;
   printf("showcase_debug_text: bye\n")
END showcase_debug_text.