Syntax10.Scn.Fnt
Syntax10b.Scn.Fnt
Syntax10i.Scn.Fnt
Math12.Scn.Fnt
Syntax12.Scn.Fnt
MODULE TextPFrames;	(** CAS 18-Jun-92 / MH 23 May 1993 / JT 07.10.93  (Rel. 2.43) **)
	IMPORT
		Modules, Input, Display, Fonts, Viewers, Oberon, MenuViewers, Texts, TextFrames, TextPrinter;
	CONST
		mm = TextFrames.mm; Scale = mm DIV 10;
		unit = TextFrames.Unit; Unit = TextPrinter.Unit;
		gridAdj = 0;  leftAdj = 1;  rightAdj = 2;  pageBreak = 3;
		AdjMask = {leftAdj, rightAdj};
		TAB = 9X; LF = 0AX; CR = 0DX; DEL = 7FX; BRK = 0ACX; ShiftBRK = 0ADX; CRSL = 0C4X; CRSR = 0C3X;
		AdjustSpan = 30; MinTabWidth = 1 * Scale; StdTabWidth = 4 * mm;
		rightKey = 0; middleKey = 1; leftKey = 2; cancel = {rightKey, middleKey, leftKey};
	TYPE
		TextLine = POINTER TO TextLineDesc;
		Location* = RECORD
			org*, pos*: LONGINT;
			x*, y*, dx*, dy*: INTEGER;
			line: TextLine;
			trunc: BOOLEAN
		END;
		TextLineDesc = RECORD
			next: TextLine;
			eot: BOOLEAN;	(*contains end of text; first line after page break*)
			indent: LONGINT;	(* first line indentation in units *)
			pno: INTEGER;	(*3 0: page number of page containing first line after page break*)
			w, h, dsr: INTEGER;	(**bounding box clipped to frame*)
			nob: INTEGER;	(*number of contained blanks; > 0 if text line wraps around*)
			org, len, span: LONGINT;	(*len w/o; span w/ trailing CR or white space, if any*)
			P: TextFrames.Parc;
			pbeg: LONGINT
		END;
		Frame* = POINTER TO FrameDesc;
		FrameDesc* = RECORD (TextFrames.FrameDesc)
			CarLoc*, SelBeg*, SelEnd*: Location;
			trailer: TextLine;	(*ring with trailer and header*)
			pages, first, width: INTEGER;	(*nof pages; if > 0: no of first page, print body width in print units*)
			porg: ARRAY 1024 OF LONGINT
		END;
		SelectMsg = RECORD (Display.FrameMsg)
			text: Texts.Text;
			beg, end: LONGINT;
			time: LONGINT
		END;
		pfnt: Fonts.Font;
		(*shared globals => get rid off in a later version?*)
		W: Texts.Writer;
		WL: Texts.Writer;
		PB: Texts.Buffer;
		B: Texts.Buffer;
		P: TextFrames.Parc;
		pbeg: LONGINT;	(*inv Pos(P) = pbeg*)
		R: Texts.Reader;
		nextCh: CHAR;	(*inv Base(R) = T => T[Pos(R)-1] = nextCh]*)
	PROCEDURE Min (x, y: INTEGER): INTEGER;
	BEGIN
		IF x < y THEN RETURN x ELSE RETURN y END
	END Min;
	PROCEDURE Max (x, y: INTEGER): INTEGER;
	BEGIN
		IF x > y THEN RETURN x ELSE RETURN y END
	END Max;
	PROCEDURE PU (x: INTEGER): INTEGER;	(*screen to printer space*)
	BEGIN RETURN SHORT((x * LONG(unit) + Unit DIV 2) DIV Unit)
	END PU;
	PROCEDURE SU (x: INTEGER): INTEGER;	(*printer to screen space*)
	BEGIN RETURN SHORT((x * LONG(Unit) + unit DIV 2) DIV unit)
	END SU;
	PROCEDURE MarkMenu (F: Frame);
		VAR R: Texts.Reader; V: Viewers.Viewer; T: Texts.Text; ch: CHAR;
	BEGIN V := Viewers.This(F.X, F.Y);
		IF (V IS MenuViewers.Viewer) & (V.dsc IS TextFrames.Frame) THEN
			T := V.dsc(TextFrames.Frame).text;
			IF T.len > 0 THEN Texts.OpenReader(R, T, T.len - 1); Texts.Read(R, ch) ELSE ch := 0X END;
			IF ch # "!" THEN Texts.Write(WL, "!"); Texts.Append(T, WL.buf) END
		END
	END MarkMenu;
	(* Element Subframes *)
	PROCEDURE InvertBorder (F: Display.Frame);
	BEGIN
		Display.ReplPattern(Display.white, Display.grey1, F.X-1, F.Y-1, F.W+2, 1, Display.invert);
		Display.ReplPattern(Display.white, Display.grey1, F.X-1, F.Y+F.H, F.W+2, 1, Display.invert);
		Display.ReplPattern(Display.white, Display.grey1, F.X-1, F.Y, 1, F.H, Display.invert);
		Display.ReplPattern(Display.white, Display.grey1, F.X+F.W, F.Y, 1, F.H, Display.invert)
	END InvertBorder;
	PROCEDURE InvalSubFrames (F: Frame; x, y, w, h: INTEGER);
		VAR p, f: Display.Frame; msg: MenuViewers.ModifyMsg;
	BEGIN
		IF (w > 0) & (h > 0) THEN f := F.dsc;
			IF f # NIL THEN p := f; f := p.next END;
			WHILE f # NIL DO
				IF (f.X < x + w) & (f.X + f.W > x) & (f.Y < y + h) & (f.Y + f.H > y) THEN p.next := f.next;
					msg.id := MenuViewers.reduce; msg.dY := 0; msg.Y := f.Y; msg.H := 0;
					f.handle(f, msg)
				ELSE p := f
				END;
				f := p.next
			END;
			f := F.dsc;
			IF (f # NIL) & (f.X < x + w) & (f.X + f.W > x) & (f.Y < y + h) & (f.Y + f.H > y) THEN F.dsc := F.dsc.next;
				msg.id := MenuViewers.reduce; msg.dY := 0; msg.Y := f.Y; msg.H := 0;
				f.handle(f, msg)
			END
		END
	END InvalSubFrames;
	PROCEDURE ShiftSubFrames (F: Frame; oldY, newY, h: INTEGER);
		VAR f: Display.Frame; msg: MenuViewers.ModifyMsg;
	BEGIN
		IF oldY > newY THEN InvalSubFrames(F, F.X, newY, F.W, oldY - newY)
		ELSE InvalSubFrames(F, F.X, oldY + h, F.W, newY - oldY)
		END;
		f := F.dsc;
		WHILE f # NIL DO
			IF (f.Y < oldY + h) & (f.Y + f.H > oldY) THEN INC(f.Y, newY - oldY);
				msg.id := MenuViewers.reduce; msg.dY := 0; msg.Y := f.Y; msg.H := f.H;
				f.handle(f, msg)
			END;
			f := f.next
		END
	END ShiftSubFrames;
	(* Display Primitives *)
	PROCEDURE DrawCursor (x, y: INTEGER);
	BEGIN Oberon.DrawCursor(Oberon.Mouse, Oberon.Arrow, x, y)
	END DrawCursor;
	PROCEDURE TrackMouse (VAR x, y: INTEGER; VAR keys, keysum: SET);
	BEGIN Input.Mouse(keys, x, y); keysum := keysum + keys; DrawCursor(x, y)
	END TrackMouse;
	PROCEDURE EraseRect (F: Frame; x, y, w, h: INTEGER);
	BEGIN Display.ReplConst(Display.black, x, y, w, h, Display.replace); InvalSubFrames(F, x, y, w, h)
	END EraseRect;
	PROCEDURE Erase (F: Frame; x, y, w, h: INTEGER);	(*RemoveMarks optimization*)
	BEGIN
		IF h > 0 THEN Oberon.RemoveMarks(x, y, w, h); EraseRect(F, x, y, w, h) END
	END Erase;
	PROCEDURE Shift (F: Frame; oldY, newY, h: INTEGER);	(*RemoveMarks optimization*)
	BEGIN
		IF (oldY # newY) & (h > 0) THEN
			Oberon.RemoveMarks(F.X + F.left, Min(oldY, newY), F.W - F.left, Max(oldY, newY) + h);
			Display.CopyBlock(F.X + F.left, oldY, F.W - F.left, h, F.X + F.left, newY, Display.replace);
			ShiftSubFrames(F, oldY, newY, h)
		END
	END Shift;
	PROCEDURE InvertCaret (F: Frame);
		VAR loc: Location;
	BEGIN loc := F.CarLoc; Display.CopyPattern(Display.white, Display.hook, loc.x, loc.y + loc.line.dsr - 6, Display.invert)
	END InvertCaret;
	PROCEDURE InvertRect (F: Frame; x, y, w, h: INTEGER);	(*clips to right and bottom frame margin*)
	BEGIN
		IF x + w > F.X + F.W - F.right THEN w := F.X + F.W - F.right - x END;
		IF y >= F.Y + F.bot THEN Display.ReplConst(Display.white, x, y, w, h, Display.invert) END
	END InvertRect;
	PROCEDURE InvertSelection (F: Frame; beg, end: Location);
		VAR t: TextLine; ex, rx, w, py: INTEGER;
	BEGIN rx := F.X + F.W - F.right; t := end.line;
		IF t.eot OR (end.pos <= t.org + t.len) THEN ex := end.x ELSE ex := rx END;
		IF beg.line = end.line THEN InvertRect(F, beg.x, beg.y, ex - beg.x, beg.line.h)
		ELSE t := beg.line; py := beg.y; w := F.W - F.left - F.right;
			InvertRect(F, beg.x, py, rx - beg.x, t.h); t := t.next; DEC(py, t.h);
			WHILE t # end.line DO InvertRect(F, F.X + F.left, py, w, t.h); t := t.next; DEC(py, t.h) END;
			IF end.line.eot THEN InvertRect(F, F.X + F.left, py, end.x - (F.X + F.left), t.h)
			ELSE InvertRect(F, F.X + F.left, py, ex - (F.X + F.left), t.h)
			END
		END
	END InvertSelection;
	PROCEDURE CoordToPos (F: Frame; mh: INTEGER): LONGINT;
		VAR h: INTEGER;
	BEGIN h := F.H - 1;
		IF h > 0 THEN RETURN ((h - mh) * F.text.len + h DIV 2) DIV h ELSE RETURN 0 END
	END CoordToPos;
	PROCEDURE ShowBar (F: Frame; botH, topH: INTEGER);
	BEGIN
		IF (F.left > F.barW) & (F.barW > 0) THEN
			Display.ReplConst(Display.white, F.X + F.barW - 1, F.Y + botH, 1, topH - botH, Display.replace)
		END
	END ShowBar;
	PROCEDURE Tick (F: Frame);
	BEGIN
		IF (0 <= F.markH) & (F.markH < F.H) & (F.left > F.barW) & (F.barW > 6) & (F.H > 1) THEN
			Display.ReplConst(Display.white, F.X + 1, F.Y + F.markH, F.barW - 6, 1, Display.invert)
		END
	END Tick;
	PROCEDURE ShowTick (F: Frame);	(*removes global marks as needed*)
		VAR h, mh: INTEGER; len: LONGINT;
	BEGIN h := F.H - 1; len := F.text.len;
		IF len > 0 THEN mh := SHORT(h - h * F.org DIV len) ELSE mh := h END;
		IF F.markH # mh THEN Oberon.RemoveMarks(F.X, F.Y, F.barW, F.H);
			Tick(F); F.markH := mh; Tick(F)
		END
	END ShowTick;
	(** Pagination Support **)
	PROCEDURE LocatePage* (F: Frame; org: LONGINT; VAR porg: LONGINT; VAR pno: INTEGER);
		VAR i: INTEGER;
	BEGIN i := 0;
		WHILE (i < F.pages) & (F.porg[i] < org) DO INC(i) END;
		IF i < F.pages THEN porg := F.porg[i]; pno := F.first + i
		ELSE porg := F.text.len; pno := LEN(F.porg)
		END
	END LocatePage;
	PROCEDURE GetPagination* (F: Frame; VAR pages, first, width: INTEGER; VAR porg: ARRAY OF LONGINT);
		VAR i: INTEGER;
	BEGIN pages := Min(F.pages, SHORT(LEN(porg))); first := F.first; width := F.width; i := pages;
		WHILE i > 0 DO DEC(i); F.porg[i] := porg[i] END
	END GetPagination;
	PROCEDURE SetPagination* (F: Frame; pages, first, width: INTEGER; VAR porg: ARRAY OF LONGINT);
	BEGIN pages := Min(pages, LEN(F.porg)); F.pages := pages; F.first := first; F.width := width;
		WHILE pages > 0 DO DEC(pages); F.porg[pages] := porg[pages] END
	END SetPagination;
	(* Screen Metrics *)
	PROCEDURE GetChar (fnt: Fonts.Font; ch: CHAR; VAR dx, x, y, w, h: INTEGER; VAR pat: Display.Pattern);
		(*dx, x, w: printer space*)
	BEGIN Display.GetChar(fnt.raster, ch, dx, x, y, w, h, pat);
		dx := SHORT(TextPrinter.DX(TextPrinter.FontNo(fnt), ch) DIV Unit);
		x := PU(x); w := PU(w)
	END GetChar;
	PROCEDURE Tab (dw: INTEGER; VAR dx: INTEGER);	(*P set*)
		VAR i, n: INTEGER; w: LONGINT;
	BEGIN i := 0; n := P.nofTabs; w := LONG(dw) * Unit + MinTabWidth;
		IF dw < 0 THEN dx := -dw
		ELSE
			WHILE (i < n) & (P.tab[i] < w) DO INC(i) END;
			IF i < n THEN dx := SHORT((P.tab[i] - LONG(dw) * Unit) DIV Unit)
			ELSE dx := StdTabWidth DIV Unit
			END
		END
	END Tab;
	PROCEDURE MeasureSpecial (dw: INTEGER; VAR dx, x, y, w, h: INTEGER; VAR trunc: BOOLEAN);
		(*P, R, nextCh set*)	(*dx, x, w: printer space*)
		VAR e: Texts.Elem; pat: Display.Pattern; pw, ph: LONGINT;
			msg: TextFrames.DisplayMsg; pmsg: TextPrinter.PrintMsg;
	BEGIN
		IF nextCh = " " THEN GetChar(R.fnt, nextCh, dx, x, y, w, h, pat);
			x := 0; y := 0; w := dx; h := 0; trunc := FALSE
		ELSIF nextCh = TAB THEN Tab(dw, dx); x := 0; y := 0; w := dx; h := 0; trunc := FALSE
		ELSIF R.elem # NIL THEN e := R.elem;
			pmsg.prepare := TRUE; pmsg.indent := LONG(dw) * Unit;
			pmsg.fnt := R.fnt; pmsg.col := R.col; pmsg.pos := Texts.Pos(R)-1;
			pmsg.Y0 := -SHORT(P.dsr DIV Unit);
			e.handle(e, pmsg); pw := e.W; ph := e.H;
			msg.prepare := TRUE; msg.indent := LONG(dw) * Unit;
			msg.fnt := R.fnt; msg.col := R.col; msg.pos := Texts.Pos(R)-1;
			msg.Y0 := -SHORT(P.dsr DIV unit);
			e.handle(e, msg);
			w := SHORT(pw DIV Unit); h := SHORT(ph DIV unit); dx := w; x := 0; y := msg.Y0;
			trunc := ~(e IS TextFrames.Parc) & ((pw < e.W) OR (ph < e.H))
		ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat); trunc := FALSE
		END
	END MeasureSpecial;
	PROCEDURE GetSpecial (F: Frame; VAR n: INTEGER; cn, ddx, dw: INTEGER;
			VAR dx, x, y, w, h: INTEGER; VAR trunc: BOOLEAN);
		(*P, R, nextCh set*)	(*ddx, dw, dx, x, w: printer space*)
		VAR e: Texts.Elem; pat: Display.Pattern;
	BEGIN
		IF nextCh = " " THEN GetChar(R.fnt, nextCh, dx, x, y, w, h, pat);
			x := 0; y := 0; INC(dx, ddx); INC(n); IF n <= cn THEN INC(dx) END;	(*space correction for block adjustment*)
			w := dx; h := 0; trunc := FALSE
		ELSIF nextCh = TAB THEN Tab(dw, dx); x := 0; y := 0; w := dx; h := 0; trunc := FALSE
		ELSIF R.elem # NIL THEN e := R.elem;
			IF (e IS TextFrames.Parc) & (P.W = 9999 * Unit) THEN
				w := Min(SHORT((P.width + P.left) DIV Unit), PU(F.W - F.right - F.left));
				e.W := w * LONG(Unit); h := SHORT(e.H DIV unit); trunc := FALSE
			ELSE MeasureSpecial(dw, dx, x, y, w, h, trunc)
			END;
			dx := w; x := 0; y := -SHORT(P.dsr DIV unit)
		ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat); trunc := FALSE
		END
	END GetSpecial;
	PROCEDURE NextLine (T: Texts.Text; VAR org: LONGINT);	(*R, nextCh set*)
		VAR pat: Display.Pattern; pos, bk, d: LONGINT; width, tw, dx, x, y, w, h: INTEGER; trunc: BOOLEAN;
			R1: Texts.Reader; peekCh: CHAR; indent: LONGINT;
	BEGIN tw := 0; dx := 0; w := 0; bk := -999;	(*org = Texts.Pos(R)-1*)
		pos := org; TextFrames.ParcBefore(T, pos, P, pbeg); width := SHORT(P.width DIV Unit);
		indent := 0;
		IF org > 0 THEN Texts.OpenReader(R1, T, org - 1); Texts.Read(R1, peekCh);
			IF (peekCh = CR) OR (R1.elem # NIL) & (R1.elem IS TextFrames.Parc) THEN indent := P.first END;
		END;
		DEC(width, SHORT(indent DIV Unit));
		LOOP INC(pos);	(*inv pos = Texts.Pos(R), ~R.eof => nextCh = text[pos-1]*)
			IF R.eot OR (nextCh = CR) THEN EXIT END;
			INC(tw, dx);
			IF nextCh <= " " THEN MeasureSpecial(tw + SHORT(indent DIV Unit), dx, x, y, w, h, trunc)
			ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat)
			END;
			IF tw + x + dx > width THEN d := pos - bk;
				IF (0 <= d) & (d < AdjustSpan) & (nextCh > " ") THEN pos := bk
				ELSIF ((nextCh > " ") OR (nextCh = Texts.ElemChar)) & (pos > org + 1) THEN DEC(pos)
				END;
				Texts.OpenReader(R, T, pos); Texts.Read(R, nextCh);
				EXIT
			END;
			IF (nextCh <= " ") & (nextCh # Texts.ElemChar) THEN bk := pos END;
			Texts.Read(R, nextCh)
		END;
		org := pos
	END NextLine;
	PROCEDURE BegOfLine* (T: Texts.Text; VAR pos: LONGINT; adjust: BOOLEAN);
		VAR p, org: LONGINT;
	BEGIN
		IF pos <= 0 THEN pos := 0
		ELSE
			IF pos <= T.len THEN org := pos ELSE org := T.len END;
			LOOP	(*search backwards for CR*)
				IF org = 0 THEN EXIT END;
				Texts.OpenReader(R, T, org - 1); Texts.Read(R, nextCh);
				IF nextCh = CR THEN EXIT END;
				DEC(org)
			END;
			IF adjust THEN	(*search forward for actual line origin*)
				Texts.OpenReader(R, T, org); Texts.Read(R, nextCh); p := org;
				REPEAT org := p; NextLine(T, p) UNTIL (p > pos) OR R.eot
			END;
			pos := org
		END
	END BegOfLine;
	PROCEDURE AdjustMetrics (F: Frame; t: TextLine; VAR pw, tw, ddx, cn: INTEGER);
		(*t.org set*)	(*pw, tw, ddx, cn: printer space*)
		VAR w: INTEGER;
	BEGIN P := t.P; pbeg := t.pbeg;
		pw := PU(F.left); tw := PU(t.w); ddx := 0; cn := 0;
		IF t.pbeg # t.org THEN
			INC(pw, SHORT((P.left + t.indent) DIV Unit));
			DEC(tw, SHORT(t.indent DIV Unit));
			IF leftAdj IN P.opts THEN
				IF (rightAdj IN P.opts) & (t.nob > 0) THEN
					w := tw; tw := SHORT((P.width - t.indent) DIV Unit);
					ddx := (tw - w) DIV t.nob; cn := (tw - w) MOD t.nob
				END
			ELSIF rightAdj IN P.opts THEN INC(pw, SHORT(P.width DIV Unit) - tw)
			ELSE (*center*) INC(pw, (SHORT(P.width DIV Unit) - tw) DIV 2)
			END
		END
	END AdjustMetrics;
	(* Screen Placement *)
	PROCEDURE DrawSpecial (F: Frame; px, py, x, y: INTEGER);	(*R, nextCh set*)	(*px, x: printer space*)
		VAR e: Texts.Elem; pat: Display.Pattern; dx, w, h: INTEGER;
			msg: TextFrames.DisplayMsg;
	BEGIN
		IF (nextCh = " ") OR (nextCh = CR) OR (nextCh = TAB) THEN (*skip*)
		ELSIF R.elem # NIL THEN e := R.elem;
			IF ~(e IS TextFrames.Parc) OR F.showsParcs THEN
				msg.prepare := FALSE;
				msg.fnt := R.fnt; msg.col := R.col; msg.pos := Texts.Pos(R) - 1;
				msg.frame := F; msg.X0 := SU(px + x); msg.Y0 := py + y;
				msg.elemFrame := NIL;
				e.handle(e, msg);
				IF msg.elemFrame # NIL THEN msg.elemFrame.next := F.dsc; F.dsc := msg.elemFrame END
			ELSIF (e IS TextFrames.Parc) & ~F.showsParcs & (pageBreak IN e(TextFrames.Parc).opts) THEN
				Display.ReplPattern(Display.white, Display.grey1, SU(px + x), py, SHORT(e.W DIV Unit), 1, Display.replace)
			END
		ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat);
			Display.CopyPattern(R.col, pat, SU(px + x), py + y, Display.replace)
		END;
	END DrawSpecial;
	PROCEDURE DrawBanner (F: Frame; pno, bw, px, py, th, mw: INTEGER);
		VAR pat: Display.Pattern; i, j, dx, x, y, w, h: INTEGER; pstr: ARRAY 5 OF CHAR;
	BEGIN
		IF bw <= mw THEN
			Display.ReplPattern(Display.white, Display.grey1, px + bw, py, 1, th, Display.replace);
			DEC(bw, 2)
		ELSE bw := mw
		END;
		INC(py, th - 18);
		i := 0; j := pno;
		REPEAT pstr[i] := CHR(30H + j MOD 10); j := j DIV 10; INC(i) UNTIL j = 0;
		WHILE j < i DO Display.GetChar(pfnt.raster, pstr[j], dx, x, y, w, h, pat); DEC(bw, dx); INC(j) END;
		Display.ReplConst(Display.white, px, py, bw - 2, 1, Display.replace);
		Display.ReplConst(Display.white, px, py + 2, bw - 2, 1, Display.replace);
		INC(px, bw);
		WHILE i > 0 DO DEC(i); Display.GetChar(pfnt.raster, pstr[i], dx, x, y, w, h, pat);
			Display.CopyPattern(Display.white, pat, px + x, py + y, Display.replace);
			INC(px, dx)
		END
	END DrawBanner;
	PROCEDURE ShowLine (F: Frame; t: TextLine; left, right, py: INTEGER);	(*left, right: printer space*)
		VAR pat: Display.Pattern; i: LONGINT; trunc: BOOLEAN;
			n, cn, lm, px, pw, tw, ddx, dx, x, y, w, h: INTEGER;
	BEGIN Texts.OpenReader(R, F.text, t.org); AdjustMetrics(F, t, pw, tw, ddx, cn);
		IF F.pages > 0 THEN
			IF SU(F.width) < F.W - F.left - F.right THEN
				Display.ReplPattern(Display.white, Display.grey1, F.X + F.left + SU(F.width), py, 1, t.h, Display.replace)
			END;
			IF t.pno >= 0 THEN
				DrawBanner(F, t.pno, SU(F.width), F.X + F.left, py, t.h, F.W - F.left - F.right)
			END
		END;
		lm := PU(F.X + F.left) + SHORT(P.left DIV Unit); px := PU(F.X) + pw; INC(py, t.dsr); i := 0; n := 0;
		WHILE i < t.len DO Texts.Read(R, nextCh);
			IF nextCh <= " " THEN GetSpecial(F, n, cn, ddx, px - lm, dx, x, y, w, h, trunc)
			ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat)
			END;
			INC(y, R.fnt.height * R.voff DIV 64);
			IF px + x + w <= right THEN
				IF px + x >= left THEN
					IF nextCh <= " " THEN
						IF trunc THEN
							Display.ReplPattern(R.col, Display.grey0, SU(px + x), py + y, SU(w), h, Display.replace)
						ELSE DrawSpecial(F, px, py, x, y)
						END
					ELSE Display.CopyPattern(R.col, pat, SU(px + x), py + y, Display.replace)
					END
				END;
				INC(px, dx); INC(i)
			ELSE i := t.len
			END
		END
	END ShowLine;
	PROCEDURE ShowLines (F: Frame; botH, topH: INTEGER);
		VAR t: TextLine; ph: INTEGER;
	BEGIN t := F.trailer.next; ph := F.H - F.top;
		WHILE (t # F.trailer) & (ph - t.h >= topH) DO DEC(ph, t.h); t := t.next END;
		WHILE (t # F.trailer) & (ph - t.h >= botH) DO DEC(ph, t.h);
			ShowLine(F, t, PU(F.X + F.left), PU(F.X + F.W - F.right), F.Y + ph); t := t.next
		END
	END ShowLines;
	PROCEDURE ShowLinesErasing (F: Frame; botH, topH: INTEGER);
		VAR t: TextLine; ph: INTEGER;
	BEGIN t := F.trailer.next; ph := F.H - F.top;
		WHILE (t # F.trailer) & (ph - t.h >= topH) DO DEC(ph, t.h); t := t.next END;
		WHILE (t # F.trailer) & (ph - t.h >= botH) DO DEC(ph, t.h);
			Erase(F, F.X + F.left, F.Y + ph, F.W - F.right - F.left, t.h);
			ShowLine(F, t, PU(F.X + F.left), PU(F.X + F.W - F.right), F.Y + ph); t := t.next
		END
	END ShowLinesErasing;
	(* Screen Casting *)
	PROCEDURE MeasureLine (F: Frame; maxW: INTEGER; t: TextLine);	(*R, nextCh set*)
		VAR pat: Display.Pattern; porg, len, bklen, d: LONGINT; eol, trunc: BOOLEAN;
			nob, bknob, width, minY, bkminY, maxY, bkmaxY, tw, bktw, lsp, dsr, dx, x, y, w, h: INTEGER;
			R1: Texts.Reader; peekCh: CHAR;
	BEGIN len := 0; nob := 0; bklen := -999; tw := 0; dx := 0; minY := 0; maxY := 0;
		TextFrames.ParcBefore(F.text, t.org, P, pbeg);
		lsp := SHORT(P.lsp DIV unit); dsr := SHORT(P.dsr DIV unit); width := SHORT(P.width DIV Unit);
		t.indent := 0;
		IF t.org > 0 THEN Texts.OpenReader(R1, F.text, t.org - 1); Texts.Read(R1, peekCh);
			IF (peekCh = CR) OR (R1.elem # NIL) & (R1.elem IS TextFrames.Parc) THEN t.indent := P.first END;
		END;
		DEC(width, SHORT(t.indent DIV Unit));
		LOOP INC(tw, dx);
			IF R.eot OR (nextCh = CR) THEN nob := 0; eol := ~R.eot; EXIT END;
			IF nextCh <= " " THEN MeasureSpecial(tw + SHORT(t.indent DIV Unit), dx, x, y, w, h, trunc)
			ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat)
			END;
			IF tw + x + dx > width THEN d := len - bklen;
				IF (0 <= d) & (d < AdjustSpan) & (nextCh > " ") THEN eol := TRUE;
					Texts.OpenReader(R, F.text, Texts.Pos(R) - d);
					nob := bknob; len := bklen; tw := bktw; minY := bkminY; maxY := bkmaxY
				ELSIF len = 0 THEN	(*force at least one character on each line*)
					INC(len); INC(y, R.fnt.height * R.voff DIV 64); minY := Min(minY, y); maxY := Max(maxY, y + h);
					Texts.Read(R, nextCh); eol := FALSE; tw := maxW
				ELSE eol := (nextCh <= " ") & (nextCh # Texts.ElemChar)
				END;
				EXIT
			END;
			IF (nextCh <= " ") & (nextCh # Texts.ElemChar) THEN
				bknob := nob; bklen := len; bktw := tw; bkminY := minY; bkmaxY := maxY;
				IF nextCh = " " THEN INC(nob) END
			END;
			INC(len); INC(y, R.fnt.height * R.voff DIV 64); minY := Min(minY, y); maxY := Max(maxY, y + h);
			Texts.Read(R, nextCh)
		END;
		IF ~F.showsParcs & (pbeg = t.org) THEN dsr := 0; t.h := SHORT(P.lead DIV unit) + 1
		ELSIF gridAdj IN P.opts THEN
			WHILE dsr < -minY DO INC(dsr, lsp) END;
			t.h := Max(lsp, dsr + maxY); INC(t.h, (-t.h) MOD lsp)
		ELSE dsr := Max(dsr, -minY); t.h := Max(lsp, dsr + maxY)
		END;
		LocatePage(F, t.org, porg, t.pno);
		IF t.org = porg THEN INC(t.h, 20) ELSE t.pno := -1 END;
		t.len := len; t.w := Min(SU(tw), maxW); t.dsr := dsr;
		t.nob := nob; t.eot := R.eot; t.P := P; t.pbeg := pbeg;
		IF eol THEN Texts.Read(R, nextCh); t.span := len + 1 ELSE t.span := len END
	END MeasureLine;
	PROCEDURE MeasureLines (F: Frame; org: LONGINT; VAR trailer: TextLine);
		VAR s, t: TextLine; ph: INTEGER;
	BEGIN NEW(trailer); s := trailer;
		Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh); ph := F.H - F.top;
		LOOP NEW(t); t.org := org; MeasureLine(F, F.W - F.left - F.right, t);
			IF ph - t.h < F.bot THEN EXIT END;
			s.next := t; s := t; INC(org, s.span); DEC(ph, s.h);
			IF R.eot THEN EXIT END
		END;
		s.next := trailer; trailer.eot := TRUE; trailer.org := org; trailer.len := 0; trailer.w := 0;
		trailer.h := SHORT(TextFrames.defParc.lsp DIV unit); trailer.P := P; trailer.pbeg := pbeg
	END MeasureLines;
	(** Locators **)
	PROCEDURE LocateLineTop (F: Frame; trailer: TextLine; org: LONGINT; VAR loc: Location);
		VAR t: TextLine; ph: INTEGER;
	BEGIN ph := F.H - F.top; t := trailer.next;
		WHILE (t # trailer) & (t.org # org) DO DEC(ph, t.h); t := t.next END;
		loc.org := org; loc.line := t; loc.y := F.Y + ph
	END LocateLineTop;
	PROCEDURE Width (F: Frame; t: TextLine; pos: LONGINT; VAR pw, dx, dy: INTEGER);	(*pw, dx: printer space*)
		VAR pat: Display.Pattern; i: LONGINT; n, mw, lm, tw, ddx, cn, x, y, w, h: INTEGER; trunc: BOOLEAN;
	BEGIN AdjustMetrics(F, t, pw, tw, ddx, cn); dy := 0; lm := PU(F.left) + SHORT(P.left DIV Unit);
		IF t # F.trailer THEN Texts.OpenReader(R, F.text, t.org); Texts.Read(R, nextCh);
			i := 0; n := 0; DEC(pos, t.org); dx := 0; mw := PU(F.W - F.right);
			WHILE ~R.eot & (i < t.len) & (i <= pos) & (pw + dx <= mw) DO INC(i); INC(pw, dx);
				IF nextCh <= " " THEN GetSpecial(F, n, cn, ddx, pw - lm, dx, x, y, w, h, trunc)
				ELSE GetChar(R.fnt, nextCh, dx, x, y, w, h, pat)
				END;
				dy := R.fnt.height * R.voff DIV 64;
				Texts.Read(R, nextCh)
			END;
			IF (i <= pos) & (pw + dx <= mw) THEN INC(i); INC(pw, dx) END
		ELSE dx := PU(4)
		END
	END Width;
	PROCEDURE LocatePos* (F: Frame; pos: LONGINT; VAR loc: Location);
		VAR t: TextLine; pw, dx, dy: INTEGER;
	BEGIN
		IF pos < F.org THEN pos := F.org; t := F.trailer.next
		ELSIF pos < F.trailer.org THEN t := F.trailer;
			WHILE (t.next # F.trailer) & (t.next.org <= pos) DO t := t.next END
		ELSE pos := F.trailer.org; t := F.trailer.next;
			WHILE ~t.eot DO t := t.next END
		END;
		Width(F, t, pos, pw, dx, dy); LocateLineTop(F, F.trailer, t.org, loc); DEC(loc.y, loc.line.h);
		loc.org := t.org; loc.pos := pos; loc.x := F.X + SU(pw); loc.dx := SU(dx); loc.dy := dy;
		loc.line := t; loc.trunc := FALSE
	END LocatePos;
	PROCEDURE LocateLine* (F: Frame; y: INTEGER; VAR loc: Location);
		VAR t: TextLine; h, ph, pw, tw, ddx, cn: INTEGER;
	BEGIN t := F.trailer.next; h := y - F.Y; ph := F.H - F.top - t.h;
		WHILE ~t.eot & (ph - t.next.h >= F.bot) & (ph > h) DO t := t.next; DEC(ph, t.h) END;
		AdjustMetrics(F, t, pw, tw, ddx, cn);
		IF pw >= PU(F.X + F.W - F.right) THEN pw := PU(F.X + F.W - F.right - 4) END;
		loc.org := t.org; loc.pos := loc.org;
		loc.x := F.X + SU(pw); loc.y := F.Y + ph; loc.dx := SU(tw); loc.dy := 0;
		loc.line := t; loc.trunc := FALSE
	END LocateLine;
	PROCEDURE LocateChar* (F: Frame; x, y: INTEGER; VAR loc: Location);
		VAR t: TextLine; pat: Display.Pattern; i: LONGINT; trunc: BOOLEAN;
			n, w, lm, pw, tw, ddx, cn, dx, xc, yc, wc, hc: INTEGER;
	BEGIN LocateLine(F, y, loc); t := loc.line; w := PU(x - F.X); AdjustMetrics(F, t, pw, tw, ddx, cn);
		lm := PU(F.left) + SHORT(P.left DIV Unit);
		IF (t # F.trailer) & (w > pw) THEN Texts.OpenReader(R, F.text, t.org);
			i := 0; n := 0; dx := 0; nextCh := 0X;
			WHILE (i < t.len) & (pw + dx < w) DO Texts.Read(R, nextCh); INC(i); INC(pw, dx);
				IF nextCh <= " " THEN GetSpecial(F, n, cn, ddx, pw - lm, dx, xc, yc, wc, hc, trunc)
				ELSE GetChar(R.fnt, nextCh, dx, xc, yc, wc, hc, pat); trunc := FALSE
				END
			END;
			IF pw + dx < w THEN INC(i); INC(pw, dx); R.elem := NIL END;
			INC(loc.pos, i - 1); loc.x := F.X + SU(pw); loc.trunc := trunc;
			IF i < t.len THEN loc.dx := SU(dx); loc.dy := R.fnt.height * R.voff DIV 64 ELSE loc.dx := 4 END
		ELSE loc.dx := 4
		END
	END LocateChar;
	PROCEDURE LocateWord* (F: Frame; x, y: INTEGER; VAR loc: Location);
		VAR t: TextLine; pos, i: LONGINT; px, rx: INTEGER; pat: Display.Pattern; dx, xc, yc, wc, hc: INTEGER;
	BEGIN LocateChar(F, x, y, loc); pos := loc.pos + 1;
		REPEAT DEC(pos); Texts.OpenReader(R, F.text, pos); Texts.Read(R, nextCh)
		UNTIL (pos < loc.org) OR (nextCh > " ");
		INC(pos);
		REPEAT DEC(pos); Texts.OpenReader(R, F.text, pos); Texts.Read(R, nextCh)
		UNTIL (pos < loc.org) OR (nextCh <= " ");
		LocatePos(F, pos + 1, loc); t := loc.line; i := loc.pos - loc.org;
		IF i < t.len THEN px := PU(loc.x); rx := PU(F.X + F.W - F.right);
			Texts.OpenReader(R, F.text, loc.pos); dx := 0; wc := 0; nextCh := "x";
			WHILE (i < t.len) & (nextCh > " ") & (px + dx < rx) DO Texts.Read(R, nextCh); INC(i); INC(px, dx);
				GetChar(R.fnt, nextCh, dx, xc, yc, wc, hc, pat)
			END;
			IF (nextCh > " ") & (px + dx < rx) THEN INC(i); INC(px, dx) END;
			loc.dx := SU(px) - loc.x
		ELSE loc.dx := 0
		END
	END LocateWord;
	PROCEDURE Pos* (F: Frame; x, y: INTEGER): LONGINT;
		VAR loc: Location;
	BEGIN LocateChar(F, x, y, loc); RETURN loc.pos
	END Pos;
	PROCEDURE ThisSubFrame* (F: Frame; x, y: INTEGER): Display.Frame;
		VAR f: Display.Frame;
	BEGIN f := F.dsc;
		WHILE (f # NIL) & ((x < f.X) OR (x >= f.X + f.W) OR (y < f.Y) OR (y >= f.Y + f.H)) DO f := f.next END;
		RETURN f
	END ThisSubFrame;
	(** Caret & Selection **)
	PROCEDURE PassSubFocus* (F: Frame; f: Display.Frame);
		VAR loc: Location; f1: Display.Frame; ctrl: Oberon.ControlMsg; focus: TextFrames.FocusMsg;
	BEGIN
		IF F.focus # NIL THEN f1 := F.focus;
			ctrl.id := Oberon.defocus; f1.handle(f1, ctrl);
			LocateChar(F, f1.X + 1, f1.Y + 1, loc);
			focus.focus := FALSE; focus.elemFrame := f1; focus.frame := F; R.elem.handle(R.elem, focus);
			InvertBorder(f1)
		END;
		IF f # NIL THEN
			LocateChar(F, f.X + 1, f.Y + 1, loc);
			focus.focus := TRUE; focus.elemFrame := f; focus.frame := F; R.elem.handle(R.elem, focus);
			InvertBorder(f)
		END;
		F.focus := f
	END PassSubFocus;
	PROCEDURE RemoveSelection* (F: Frame);
	BEGIN
		IF F.hasSel THEN InvertSelection(F, F.SelBeg, F.SelEnd); F.hasSel := FALSE END
	END RemoveSelection;
	PROCEDURE SetSelection* (F: Frame; beg, end: LONGINT);	(**forces range to visible bounds**)
		VAR loc: Location;
	BEGIN
		IF end > F.text.len THEN end := F.text.len END;
		IF end > beg THEN
			IF F.hasSel & (F.SelBeg.pos = beg) THEN
				IF (F.SelEnd.pos < end) & (F.SelEnd.pos < F.trailer.org) THEN
					LocatePos(F, F.SelEnd.pos, loc); LocatePos(F, end, F.SelEnd); InvertSelection(F, loc, F.SelEnd)
				ELSIF end < F.SelEnd.pos THEN
					LocatePos(F, end, loc); InvertSelection(F, loc, F.SelEnd); LocatePos(F, end, F.SelEnd)
				END
			ELSIF ~F.hasSel OR (F.SelBeg.pos # beg) OR (F.SelEnd.pos # end) THEN
				RemoveSelection(F); PassSubFocus(F, NIL);
				LocatePos(F, beg, F.SelBeg); LocatePos(F, end, F.SelEnd); InvertSelection(F, F.SelBeg, F.SelEnd)
			END;
			F.hasSel := TRUE; F.time := Oberon.Time()
		END
	END SetSelection;
	PROCEDURE RemoveCaret* (F: Frame);
		VAR msg: Oberon.ControlMsg;
	BEGIN
		IF F.focus # NIL THEN msg.id := Oberon.defocus; F.focus.handle(F.focus, msg) END;
		IF F.hasCar THEN InvertCaret(F); F.hasCar := FALSE END
	END RemoveCaret;
	PROCEDURE SetCaret* (F: Frame; pos: LONGINT);	(**only done if within visible bounds**)
	BEGIN
		IF ~F.hasCar OR (F.CarLoc.pos # pos) THEN RemoveCaret(F); PassSubFocus(F, NIL);
			LocatePos(F, pos, F.CarLoc);
			IF (F.H - F.top - F.bot >= F.CarLoc.line.h) & (F.CarLoc.x <= F.X + F.W - F.right) THEN
				LocateChar(F, F.CarLoc.x + 1, F.CarLoc.y, F.CarLoc); (*prevent "dangling" caret at right margin*)
				IF F.CarLoc.pos = pos THEN InvertCaret(F); F.hasCar := TRUE END
			END
		END
	END SetCaret;
	PROCEDURE Neutralize* (F: Frame);
		VAR f: Display.Frame; msg: Oberon.ControlMsg;
	BEGIN RemoveCaret(F); RemoveSelection(F);
		f := F.dsc; msg.id := Oberon.neutralize;
		WHILE f # NIL DO f.handle(f, msg);
			IF f = F.focus THEN PassSubFocus(F, NIL) END;
			f := f.next
		END
	END Neutralize;
	(** Display Range **)
	PROCEDURE Complete (F: Frame; trailer: TextLine; VAR s: TextLine; VAR org: LONGINT; VAR ph: INTEGER);
		VAR u: TextLine;
	BEGIN
		IF ph > F.bot THEN	(*try to add new lines to the bottom*)
			Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh);
			LOOP
				IF R.eot THEN EXIT END;
				NEW(u); u.org := org; MeasureLine(F, F.W - F.left - F.right, u);
				IF ph - u.h < F.bot THEN EXIT END;
				s.next := u; s := s.next; DEC(ph, s.h); INC(org, s.span)
			END
		END;
		s.next := trailer; trailer.eot := TRUE; trailer.org := org; trailer.len := 0; trailer.w := 0;
		trailer.h := SHORT(TextFrames.defParc.lsp DIV unit); trailer.P := P; trailer.pbeg := pbeg
	END Complete;
	PROCEDURE ShowFrom (F: Frame; pos: LONGINT);	(*removes global marks as needed and neutralizes F*)
		VAR new, s: TextLine; beg, end: Location; org: LONGINT; ph, y0, dy: INTEGER;
	BEGIN Neutralize(F);
		IF (F.trailer # NIL) & (F.org < pos) & (pos < F.trailer.org) THEN	(*shift up and extend to the bottom*)
			LocateLineTop(F, F.trailer, pos, beg); LocateLineTop(F, F.trailer, F.trailer.org, end);
			dy := (F.Y + F.H - F.top) - beg.y; Shift(F, end.y, end.y + dy, beg.y - end.y);
			Erase(F, F.X + F.left, end.y, F.W - F.left, dy);
			s := F.trailer.next; WHILE s.org # pos DO s := s.next END;
			F.trailer.next := s; org := s.org + s.span; ph := F.H - F.top - s.h;
			Complete(F, F.trailer, s, org, ph); F.org := pos; ShowLines(F, F.bot, end.y + dy - F.Y)
		ELSIF (F.trailer = NIL) OR (pos # F.org) THEN MeasureLines(F, pos, new);
			IF (F.trailer # NIL) & (pos < F.org) & (F.org <= new.org) THEN	(*shift down and extend to the top*)
				LocateLineTop(F, new, F.org, beg); LocateLineTop(F, new, new.org, end);
				y0 := F.Y + F.H - F.top; Shift(F, y0 - (beg.y - end.y), end.y, beg.y - end.y);
				Erase(F, F.X + F.left, beg.y, F.W - F.left, y0 - beg.y);
				Erase(F, F.X + F.left, F.Y + F.bot, F.W - F.left, end.y - (F.Y + F.bot));
				F.org := pos; F.trailer := new; ShowLines(F, beg.y - F.Y, F.H - F.top)
			ELSE	(*full redisplay*)
				IF F.trailer = NIL THEN Erase(F, F.X, F.Y, F.W, F.H); ShowBar(F, 0, F.H); F.markH := -1
				ELSE Erase(F, F.X + F.left, F.Y + F.bot, F.W - F.left, F.H - F.bot - F.top)
				END;
				F.org := pos; F.trailer := new; ShowLines(F, F.bot, F.H - F.top)
			END
		END;
		ShowTick(F)
	END ShowFrom;
	PROCEDURE Show* (F: Frame; pos: LONGINT);	(**removes global marks as needed and neutralizes F**)
	BEGIN BegOfLine(F.text, pos, TRUE); ShowFrom(F, pos)
	END Show;
	PROCEDURE Resize* (F: Frame; x, y, w, h: INTEGER);
		VAR loc: Location; oldY, oldH, dh: INTEGER;
	BEGIN
		IF (w = 0) OR (h = 0) THEN InvalSubFrames(F, F.X, F.Y, F.W, F.H);
			F.X := x; F.Y := y; F.W := w; F.H := h; F.trailer := NIL
		ELSIF (F.trailer # NIL) & (x = F.X) & (w = F.W) THEN
			oldY := F.Y; oldH := F.H; Tick(F); F.markH := -1; F.Y := y; F.H := h;
			IF h > oldH THEN dh := h - oldH;
				Display.CopyBlock(x, oldY, w, oldH, x, y + dh, Display.replace);
				ShiftSubFrames(F, oldY, y + dh, oldH);
				EraseRect(F, x, y, w, dh); ShowBar(F, 0, dh);
				LocateLineTop(F, F.trailer, F.trailer.org, loc); MeasureLines(F, F.org, F.trailer);
				ShowLines(F, F.bot, loc.y - F.Y)
			ELSE dh := oldH - h;
				MeasureLines(F, F.org, F.trailer); LocateLineTop(F, F.trailer, F.trailer.org, loc);
				Display.CopyBlock(x, oldY + dh, w, h, x, y, Display.replace);
				ShiftSubFrames(F, oldY + dh, y, h);
				EraseRect(F, x + F.left, y, w - F.left, loc.y - F.Y);
				InvalSubFrames(F, x, oldY, w, y - oldY); InvalSubFrames(F, x, y + h, w, dh - (y - oldY))
			END;
			ShowTick(F)
		ELSE F.X := x; F.Y := y; F.W := w; F.H := h; F.trailer := NIL; Show(F, F.org)
		END
	END Resize;
	(** Contents Update **)
	PROCEDURE Update* (F: Frame; VAR msg: TextFrames.UpdateMsg);	(**removes global marks as needed**)
		VAR t: TextLine; org, d: LONGINT;
		PROCEDURE Begin (VAR beg: LONGINT; VAR org0: LONGINT; VAR q: TextLine);
			(*returns q # NIL if beg > org0*)
			VAR trailer, t: TextLine; p: LONGINT;
		BEGIN trailer := F.trailer; t := trailer; q := NIL;
			WHILE (t.next # trailer) & (t.next.org + t.next.span <= beg) & ~t.next.eot DO t := t.next END;
			IF (t # trailer) & (t.next # trailer) & (beg <= t.next.org + t.next.span) THEN
				Texts.OpenReader(R, F.text, t.org); Texts.Read(R, nextCh); p := t.org; NextLine(F.text, p);
				IF p = t.next.org THEN q := t.next; org0 := q.org ELSE org0 := t.org; beg := org0 END
			ELSE BegOfLine(F.text, beg, TRUE);
				IF (msg.beg < beg + AdjustSpan) & (F.org < beg) THEN DEC(beg); BegOfLine(F.text, beg, TRUE) END;
				org0 := beg
			END
		END Begin;
		PROCEDURE Adjust (end, delta: LONGINT);
			VAR new, old, s, t, u, p, q: TextLine; bot: Location;
				org, org0, beg: LONGINT; ph, h0, h1, H1, h2, lm, dx, dy: INTEGER;
		BEGIN q := NIL; LocateLineTop(F, F.trailer, F.trailer.org, bot);
			IF msg.beg < F.org THEN org0 := F.org; beg := org0 ELSE beg := msg.beg; Begin(beg, org0, q) END;
			NEW(new); s := new; old := F.trailer; t := old; org := F.org; ph := F.H - F.top;
			WHILE (t.next # old) & (t.next.org # org0) DO t := t.next;	(*transfer unchanged prefix*)
				s.next := t; s := t; DEC(ph, s.h); INC(org, s.span)
			END;
			h0 := ph; H1 := h0; t := t.next; p := s;
			Texts.OpenReader(R, F.text, org); Texts.Read(R, nextCh);	(*rebuilt at least one line descriptor*)
			LOOP NEW(u); u.org := org; MeasureLine(F, F.W - F.left - F.right, u);
				IF ph - u.h < F.bot THEN h1 := ph; h2 := h1; EXIT END;
				s.next := u; s := s.next; DEC(ph, s.h); INC(org, s.span);
				IF R.eot THEN h1 := ph; h2 := h1; EXIT END;
				IF org > end THEN
					WHILE (t # old) & (org > t.org + delta) DO DEC(H1, t.h); t := t.next END;
					IF (org = t.org + delta) & (P = t.P) THEN h1 := ph;	(*resynchronized*)
						WHILE (t # old) & (ph - t.h >= F.bot) DO	(*transfer unchanged suffix*)
							s.next := t; s := t; s.org := org; TextFrames.ParcBefore(F.text, s.org, s.P, s.pbeg);
							DEC(ph, s.h); INC(org, s.span); t := t.next
						END;
						h2 := ph; EXIT
					END
				END
			END;
			Shift(F, F.Y + h2 + (H1 - h1), F.Y + h2, h1 - h2);
			Complete(F, new, s, org, ph); F.trailer := new; t := p.next;
			IF (q # NIL) & (q.h = t.h) & (q.dsr = t.dsr) & (q.org = t.org) & (q.P = t.P) & (end <= t.org + t.len) THEN
				P := t.P; pbeg := t.pbeg;
				IF (P.opts * AdjMask = {leftAdj}) OR (P.opts * AdjMask = AdjMask) & (q.nob = 0) & (t.nob = 0) THEN
					Width(F, t, beg, lm, dx, dy);	(*preserve prefix of first affected line*)
					DEC(h0, t.h); Erase(F, F.X + SU(lm), F.Y + h0, F.W - SU(lm), t.h);
					ShowLine(F, t, PU(F.X) + lm, PU(F.X + F.W - F.right), F.Y + h0)
				END
			END;
			ShowLinesErasing(F, h1, h0);
			Erase(F, F.X + F.left, bot.y, F.W - F.left, h2 - (bot.y - F.Y)); ShowLines(F, F.bot, h2)
		END Adjust;
	BEGIN
		IF (msg.id = Texts.insert) & (msg.beg < F.org) THEN t := F.trailer; d := msg.end - msg.beg; INC(F.org, d);
			REPEAT INC(t.org, d); t := t.next UNTIL t = F.trailer
		ELSIF (msg.id = Texts.delete) & (msg.end <= F.org) THEN t := F.trailer; d := msg.end - msg.beg; DEC(F.org, d);
			REPEAT DEC(t.org, d); t := t.next UNTIL t = F.trailer
		END;
		org := F.org;
		IF msg.beg <= F.org + AdjustSpan THEN BegOfLine(F.text, org, TRUE) END;
		TextFrames.ParcBefore(F.text, org, P, d);
		IF (org # F.org) OR (P # F.trailer.next.P) OR (F.pages # 0) THEN
			F.trailer := NIL; F.pages := 0; Show(F, F.org)
		ELSIF (msg.end > org) & (msg.beg < F.trailer.org + AdjustSpan) THEN
			IF msg.id = Texts.replace THEN Adjust(msg.end, 0)
			ELSIF msg.id = Texts.insert THEN Adjust(msg.end, msg.end - msg.beg)
			ELSIF msg.id = Texts.delete THEN Adjust(msg.beg, msg.beg - msg.end)
			END
		END;
		ShowTick(F)
	END Update;
	(** User Interface **)
	PROCEDURE TrackLine* (F: Frame; VAR x, y: INTEGER; VAR org: LONGINT; VAR keysum: SET);
		VAR keys: SET; new, old: Location;
	BEGIN LocateLine(F, y, old); InvertRect(F, old.x, old.y, old.dx + 4, 2);
		REPEAT TrackMouse(x, y, keys, keysum); LocateLine(F, y, new);
			IF new.org # old.org THEN
				InvertRect(F, new.x, new.y, new.dx + 4, 2); InvertRect(F, old.x, old.y, old.dx + 4, 2); old := new
			END
		UNTIL keys = {};
		InvertRect(F, new.x, new.y, new.dx + 4, 2); org := new.org
	END TrackLine;
	PROCEDURE TrackWord* (F: Frame; VAR x, y: INTEGER; VAR pos: LONGINT; VAR keysum: SET);
		VAR keys: SET; new, old: Location;
	BEGIN LocateWord(F, x, y, old); InvertRect(F, old.x, old.y, old.dx, 2);
		REPEAT TrackMouse(x, y, keys, keysum); LocateWord(F, x, y, new);
			IF new.pos # old.pos THEN
				InvertRect(F, new.x, new.y, new.dx, 2); InvertRect(F, old.x, old.y, old.dx, 2); old := new
			END
		UNTIL keys = {};
		InvertRect(F, new.x, new.y, new.dx, 2); pos := new.pos
	END TrackWord;
	PROCEDURE TrackCaret* (F: Frame; VAR x, y: INTEGER; VAR keysum: SET);
		VAR keys: SET;
	BEGIN
		REPEAT TrackMouse(x, y, keys, keysum); SetCaret(F, Pos(F, x, y)) UNTIL keys = {}
	END TrackCaret;
	PROCEDURE TrackSelection* (F: Frame; VAR x, y: INTEGER; VAR keysum: SET);
		VAR keys: SET; pos: LONGINT; V: Viewers.Viewer; f: Frame;
	BEGIN V := Viewers.This(F.X, F.Y); V := V.next(Viewers.Viewer);
		IF (V.dsc # NIL) & (V.dsc.next # NIL) & (V.dsc.next IS Frame) THEN f := V.dsc.next(Frame);
			IF f.hasSel & (f.text = F.text) THEN
				IF (f.SelBeg.pos < f.trailer.org) & (f.org < f.SelEnd.pos) & (f.SelBeg.pos <= Pos(F, x, y)) THEN
					SetSelection(F, f.SelBeg.pos, Pos(F, x, y) + 1)
				ELSE RemoveSelection(f); f := NIL
				END
			ELSE f := NIL
			END
		ELSE f := NIL
		END;
		IF f = NIL THEN
			IF F.hasSel & (F.SelBeg.pos + 1 = F.SelEnd.pos) & (Pos(F, x, y) = F.SelBeg.pos) THEN
				SetSelection(F, F.SelBeg.org, Pos(F, x, y) + 1)
			ELSE SetSelection(F, Pos(F, x, y), Pos(F, x, y) + 1)
			END
		END;
		REPEAT TrackMouse(x, y, keys, keysum); pos := Pos(F, x, y) + 1;
			IF F.hasSel THEN
				IF pos > F.SelBeg.pos THEN SetSelection(F, F.SelBeg.pos, pos);
					IF f # NIL THEN SetSelection(f, f.SelBeg.pos, pos); f.SelEnd.pos := F.SelEnd.pos END
				END
			ELSE SetSelection(F, Pos(F, x, y), Pos(F, x, y) + 1)
			END
		UNTIL keys = {};
		IF f # NIL THEN F.SelBeg.pos := f.SelBeg.pos END
	END TrackSelection;
	PROCEDURE Call* (F: Frame; pos: LONGINT; new: BOOLEAN);
		VAR S: Texts.Scanner; par: Oberon.ParList; res: INTEGER;
	BEGIN Texts.OpenScanner(S, F.text, pos); Texts.Scan(S);
		IF (S.line = 0) & (S.class = Texts.Name) THEN NEW(par); par.frame := F; par.text := F.text; par.pos := Texts.Pos(S)-1;
			Oberon.Call(S.s, par, new, res);
			IF res > 1 THEN Texts.WriteString(WL, "Call error: "); Texts.WriteString(WL, Modules.importing);
				IF res = 2 THEN Texts.WriteString(WL, " not an obj-file")
				ELSIF res = 3 THEN Texts.WriteString(WL, " imports ");
					Texts.WriteString(WL, Modules.imported); Texts.WriteString(WL, " with bad key")
				ELSIF res = 4 THEN Texts.WriteString(WL, " corrupted obj file")
				ELSIF res = 6 THEN Texts.WriteString(WL, " has too many imports")
				ELSIF res = 7 THEN Texts.WriteString(WL, " not enough space")
				END;
				Texts.WriteLn(WL); Texts.Append(Oberon.Log, WL.buf)
			END
		END
	END Call;
	PROCEDURE ShiftBlock (F: Frame; delta: INTEGER);
		VAR text: Texts.Text; pos, beg, end, time: LONGINT; select: SelectMsg; ch: CHAR;
	BEGIN Oberon.GetSelection(text, beg, end, time);
		IF (time >= 0) & (text = F.text) THEN BegOfLine(F.text, beg, FALSE); pos := beg;
			WHILE pos < end DO Texts.OpenReader(R, F.text, pos); Texts.Read(R, ch);
				WHILE (R.elem # NIL) & (R.elem IS TextFrames.Parc) & (pos < end) DO Texts.Read(R, ch); INC(pos) END;
				IF pos < end THEN
					IF delta < 0 THEN
						IF (ch <= " ") & (ch # CR) & (ch # Texts.ElemChar) THEN
							Texts.Delete(F.text, pos, pos + 1); DEC(end)
						END
					ELSE
						IF (ch <= " ") & (ch # CR) & (ch # Texts.ElemChar) THEN Texts.Write(W, ch)	(*first char extension*)
						ELSE Texts.Write(W, TAB)
						END;
						Texts.Insert(F.text, pos, W.buf); INC(end); INC(pos)
					END;
					Texts.OpenReader(R, F.text, pos);
					REPEAT Texts.Read(R, ch) UNTIL R.eot OR (ch = CR);
					pos := Texts.Pos(R)
				END
			END;
			select.text := F.text; select.beg := beg; select.end := pos; select.time := Oberon.Time();
			Viewers.Broadcast(select)
		END
	END ShiftBlock;
	PROCEDURE Write* (F: Frame; ch: CHAR; fnt: Fonts.Font; col, voff: SHORTINT);
		VAR loc: Location; parc: TextFrames.Parc; org, pos, pbeg: LONGINT; i: INTEGER; ch0: CHAR;
			buf: ARRAY 32 OF CHAR;
			copy: Texts.CopyMsg; input: Oberon.InputMsg;
		PROCEDURE Visible(ch: CHAR): BOOLEAN;
			VAR pat: Display.Pattern; dx, x, y, w, h: INTEGER;
		BEGIN GetChar(W.fnt, ch, dx, x, y, w, h, pat); RETURN dx > 0
		END Visible;
		PROCEDURE InsertBuffer;
			VAR i, j: INTEGER; ch: CHAR;
		BEGIN i := 0; j := 0; ch := buf[i];
			WHILE ch # 0X DO
				IF (ch = TAB) OR (ch = CR) OR (ch = " ") OR Visible(ch) THEN Texts.Write(W, ch); INC(j) END;
				INC(i); ch := buf[i]
			END; 
			IF j > 0 THEN Texts.Insert(F.text, pos, W.buf); INC(pos, LONG(j)) END
		END InsertBuffer;
		PROCEDURE Flush;
			VAR ch: CHAR;
		BEGIN
			WHILE Input.Available() > 0 DO Input.Read(ch) END
		END Flush;
	BEGIN
		IF F.hasCar THEN pos := F.CarLoc.pos;
			IF (ch = DEL) & (pos > F.org) THEN DEC(pos); Texts.Delete(F.text, pos, pos + 1); Flush
			ELSIF (ch = CRSL) & (pos > 0) THEN DEC(pos)
			ELSIF (ch = CRSR) & (pos < F.text.len) THEN INC(pos)
			ELSIF (ch = BRK) OR (ch = ShiftBRK) THEN
				TextFrames.ParcBefore(F.text, pos, P, pbeg); P.handle(P, copy); parc := copy.e(TextFrames.Parc);
				IF ch = BRK THEN EXCL(parc.opts, pageBreak) ELSE INCL(parc.opts, pageBreak) END;
				Texts.SetFont(W, fnt); Texts.SetColor(W, col); Texts.SetOffset(W, voff);
				Texts.WriteElem(W, parc); Texts.Insert(F.text, pos, W.buf); INC(pos)
			ELSIF (ch = TAB) OR (ch = LF) OR (ch = CR) OR (ch >= " ") THEN
				IF F.text.len > 0 THEN
					IF pos < F.text.len THEN Texts.OpenReader(R, F.text, pos); Texts.Read(R, ch0) END;
					IF (pos > 0) & ((pos = F.text.len) OR (ch0 <= " ")) THEN
						Texts.OpenReader(R, F.text, pos - 1); Texts.Read(R, ch0)
					END;
					Texts.SetFont(W, R.fnt); Texts.SetColor(W, R.col);
					IF (ch = CR) OR (ch = TAB) OR (ch = LF) THEN Texts.SetOffset(W, voff) ELSE Texts.SetOffset(W, R.voff) END
				ELSE Texts.SetFont(W, fnt); Texts.SetColor(W, col); Texts.SetOffset(W, voff)
				END;
				IF ch = LF THEN buf[0] := CR; i := 1; org := F.CarLoc.org; BegOfLine(F.text, org, FALSE);
					Texts.OpenReader(R, F.text, org);
					REPEAT Texts.Read(R, ch) UNTIL (R.elem = NIL) OR ~(R.elem IS TextFrames.Parc);
					WHILE (Texts.Pos(R) <= pos) & (ch <= " ") & (ch # Texts.ElemChar) & (i < 31) DO
						buf[i] := ch; INC(i); Texts.Read(R, ch)
					END
				ELSE buf[0] := ch; i := 1
				END;
				WHILE (Input.Available() > 0) & (i < 31) & (ch >= " ") & (ch < DEL) DO Input.Read(buf[i]); INC(i) END;
				buf[i] := 0X; InsertBuffer
			END;
			IF pos < F.org THEN Show(F, F.org - 1)
			ELSIF pos < F.text.len THEN org := -1;
				WHILE (pos >= F.trailer.org) & (F.org # org) DO Show(F, F.trailer.next.next.org); Flush; org := F.org END
			ELSE LocatePos(F, pos, loc); LocateChar(F, loc.x + 1, loc.y, loc);
				IF pos # loc.pos THEN Show(F, F.trailer.next.next.org); Flush END
			END;
			SetCaret(F, pos)
		ELSIF F.focus # NIL THEN input.id := Oberon.consume; input.ch := ch;
			input.fnt := fnt; input.col := col; input.voff := voff; F.focus.handle(F.focus, input)
		ELSIF F.hasSel THEN
			IF ch = CRSL THEN ShiftBlock(F, -1); Flush ELSIF ch = CRSR THEN ShiftBlock(F, 1); Flush END
		END
	END Write;
	PROCEDURE TouchElem* (F: Frame; VAR x, y: INTEGER; VAR keysum: SET);
		VAR loc: Location; e: Texts.Elem; pbeg: LONGINT; y0: INTEGER;
			track: TextFrames.TrackMsg;
	BEGIN LocateChar(F, x, y, loc); e := R.elem;
		IF (e # NIL) & (loc.x + e.W DIV unit <= F.X + F.W - F.right) THEN
			TextFrames.ParcBefore(F.text, loc.pos, P, pbeg);
			y0 := loc.y + loc.line.dsr - SHORT(P.dsr DIV unit) + loc.dy;
			IF (loc.x <= x) & (x < loc.x + e.W DIV unit) & ~loc.trunc THEN
				track.X := x; track.Y := y; track.keys := keysum;
				track.fnt := R.fnt; track.col := R.col; track.pos := Texts.Pos(R) - 1;
				track.frame := F; track.X0 := loc.x; track.Y0 := y0;
				e.handle(e, track); Input.Mouse(keysum, x, y)
			END
		END
	END TouchElem;
	PROCEDURE Edit* (F: Frame; x, y: INTEGER; keysum: SET);
		VAR ef: Display.Frame; text: Texts.Text; beg, end, time, pos: LONGINT; keys: SET; ch: CHAR;
			copyover: Oberon.CopyOverMsg; input: Oberon.InputMsg;
	BEGIN
		IF x < F.X + F.barW THEN	(*scroll bar*)
			IF leftKey IN keysum THEN TrackLine(F, x, y, pos, keysum)
			ELSIF middleKey IN keysum THEN
				REPEAT TrackMouse(x, y, keys, keysum) UNTIL keys = {};
				IF keysum = {middleKey, leftKey} THEN pos := F.text.len; BegOfLine(F.text, pos, TRUE)
				ELSIF keysum = {middleKey, rightKey} THEN pos := 0
				ELSIF (F.Y <= y) & (y <= F.Y + F.H) THEN pos := CoordToPos(F, y - F.Y); BegOfLine(F.text, pos, TRUE)
				ELSE pos := F.org
				END
			ELSIF rightKey IN keysum THEN
				REPEAT TrackMouse(x, y, keys, keysum) UNTIL keys = {};
				pos := 0
			ELSE DrawCursor(x, y)
			END;
			IF (keysum # {}) & (keysum # cancel) THEN ShowFrom(F, pos) END
		ELSE	(*text area*)
			ef := ThisSubFrame(F, x, y);
			IF ef # NIL THEN	(*within sub-frame*)
				IF (F.focus # ef) & (keysum = {leftKey}) THEN
					REPEAT TrackMouse(x, y, keys, keysum) UNTIL keys = {};
					IF keysum = {leftKey} THEN RemoveSelection(F); RemoveCaret(F); PassSubFocus(F, ef); RETURN
					END
				ELSIF F.focus = ef THEN input.id := Oberon.track; input.keys := keysum; input.X := x; input.Y := y;
					ef.handle(ef, input); RETURN
				END
			END;
			IF keysum # {} THEN TouchElem(F, x, y, keysum) END;
			IF leftKey IN keysum THEN Oberon.PassFocus(Viewers.This(F.X, F.Y)); TrackCaret(F, x, y, keysum);
				IF (keysum = {leftKey, middleKey}) & F.hasCar THEN Oberon.GetSelection(text, beg, end, time);
					IF time >= 0 THEN Texts.Save(text, beg, end, B);
						Texts.Insert(F.text, F.CarLoc.pos, B); SetCaret(F, F.CarLoc.pos + (end - beg))
					END
				ELSIF (keysum = {leftKey, rightKey}) & F.hasCar & (F.CarLoc.pos < F.text.len) THEN
					Oberon.GetSelection(text, beg, end, time);
					IF time >= 0 THEN Texts.OpenReader(R, F.text, F.CarLoc.pos); Texts.Read(R, ch);
						Texts.ChangeLooks(text, beg, end, {0, 1, 2}, R.fnt, R.col, R.voff)
					END
				END
			ELSIF middleKey IN keysum THEN TrackWord(F, x, y, pos, keysum);
				IF keysum # cancel THEN Call(F, pos, keysum = {middleKey, leftKey}) END
			ELSIF rightKey IN keysum THEN TrackSelection(F, x, y, keysum);
				IF keysum = {rightKey, middleKey} THEN
					copyover.text := F.text; copyover.beg := F.SelBeg.pos; copyover.end := F.SelEnd.pos;
					Oberon.FocusViewer.handle(Oberon.FocusViewer, copyover)
				ELSIF (keysum = {rightKey, leftKey}) & F.hasSel THEN Oberon.PassFocus(Viewers.This(F.X, F.Y));
					Texts.Delete(F.text, F.SelBeg.pos, F.SelEnd.pos); SetCaret(F, F.SelBeg.pos)
				END
			ELSE DrawCursor(x, y)
			END
		END
	END Edit;
	(** General **)
	PROCEDURE NotifyElems* (F: Frame; VAR msg: Display.FrameMsg);
		VAR p, f: Display.Frame;
	BEGIN f := F.dsc;
		IF msg IS TextFrames.NotifyMsg THEN msg(TextFrames.NotifyMsg).frame := F END;
		WHILE f # NIL DO p := f; f := f.next; p.handle(p, msg) END
	END NotifyElems;
	PROCEDURE Copy* (SF, DF: Frame);
		VAR i: INTEGER;
	BEGIN (*TextFrames.Copy(SF, DF)*)
		DF.handle := SF.handle; DF.text := SF.text; DF.org := SF.org;
		DF.left := SF.left; DF.right := SF.right; DF.top := SF.top; DF.bot := SF.bot;
		DF.barW := SF.barW; DF.hasCar := FALSE; DF.hasSel := FALSE;
		DF.trailer := NIL; DF.pages := SF.pages; DF.first := SF.first; DF.width := SF.width;
		i := SF.pages;
		WHILE i > 0 DO DEC(i); DF.porg[i] := SF.porg[i] END
	END Copy;
	PROCEDURE Open* (F: Frame; T: Texts.Text; pos: LONGINT);
	BEGIN TextFrames.Open(F, T, pos);
		F.trailer := NIL; F.pages := 0
	END Open;
	PROCEDURE Handle* (f: Display.Frame; VAR msg: Display.FrameMsg);
		VAR F, F1: Frame;
	BEGIN F := f(Frame);
		IF msg IS Oberon.InputMsg THEN
			WITH msg: Oberon.InputMsg DO
				IF msg.id = Oberon.consume THEN Write(F, msg.ch, msg.fnt, msg.col, msg.voff)
				ELSIF msg.id = Oberon.track THEN Edit(F, msg.X, msg.Y, msg.keys)
				END
			END
		ELSIF msg IS Oberon.ControlMsg THEN NotifyElems(F, msg);
			WITH msg: Oberon.ControlMsg DO
				IF msg.id = Oberon.defocus THEN RemoveCaret(F)
				ELSIF msg.id = Oberon.neutralize THEN Neutralize(F)
				END
			END
		ELSIF msg IS Oberon.CopyMsg THEN NEW(F1); Copy(F, F1); msg(Oberon.CopyMsg).F := F1
		ELSIF msg IS TextFrames.UpdateMsg THEN NotifyElems(F, msg);
			WITH msg: TextFrames.UpdateMsg DO
				IF msg.text = F.text THEN MarkMenu(F); Neutralize(F); Update(F, msg) END
			END
		ELSIF msg IS Oberon.SelectionMsg THEN NotifyElems(F, msg);
			WITH msg: Oberon.SelectionMsg DO
				IF F.hasSel & (F.time > msg.time) THEN
					msg.text := F.text; msg.beg := F.SelBeg.pos; msg.end := F.SelEnd.pos; msg.time := F.time
				END
			END
		ELSIF msg IS Oberon.CopyOverMsg THEN NotifyElems(F, msg);
			WITH msg: Oberon.CopyOverMsg DO
				IF F.hasCar THEN Texts.Save(msg.text, msg.beg, msg.end, B);
					Texts.Insert(F.text, F.CarLoc.pos, B); SetCaret(F, F.CarLoc.pos + (msg.end - msg.beg))
				END
			END
		ELSIF msg IS MenuViewers.ModifyMsg THEN
			WITH msg: MenuViewers.ModifyMsg DO Neutralize(F); Resize(F, F.X, msg.Y, F.W, msg.H) END
		ELSIF msg IS SelectMsg THEN NotifyElems(F, msg);
			WITH msg: SelectMsg DO
				IF (msg.text = F.text) & ~F.hasSel THEN Oberon.RemoveMarks(F.X, F.Y, F.W, F.H); Neutralize(F);
					SetSelection(F, msg.beg, msg.end); F.time := msg.time;
					IF F.hasSel THEN F.SelBeg.pos := msg.beg; F.SelEnd.pos := msg.end END
				END
			END
		ELSE NotifyElems(F, msg)
		END
	END Handle;
	PROCEDURE NewText* (T: Texts.Text; pos: LONGINT): Frame;
		VAR frame: Frame;
	BEGIN NEW(frame);
		TextFrames.Open(frame, T, pos);
		frame.handle := Handle;
		RETURN frame
	END NewText;
BEGIN Texts.OpenWriter(W); Texts.OpenWriter(WL);
	NEW(PB); Texts.OpenBuf(PB); NEW(B); Texts.OpenBuf(B);
	pfnt := Fonts.This("Syntax8.Scn.Fnt");
	TextPrinter.InitFonts
END TextPFrames.