83 lines
1.8 KiB
ObjectPascal
83 lines
1.8 KiB
ObjectPascal
// Процедура drawGraph рисования графика функции в полном окне
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// с масштабированием по оси OY
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// Перерисовывает график при изменении размеров окна
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uses GraphABC;
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type FUN = function (x: real): real;
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function f(x: real): real;
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begin
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Result := x*sin(x)*exp(-0.1*x);
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end;
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// l (logical) - логические координаты
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// s (screen) - физические координаты
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procedure drawGraph(x1,x2: real; f: FUN);
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var
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xl0,wl,yl0,hl: real;
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xs0,ws,ys0,hs: integer;
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function LtoSx(xl: real): integer;
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begin
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Result := round(ws/wl*(xl-xl0)+xs0);
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end;
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function LtoSy(yl: real): integer;
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begin
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Result := round(hs/hl*(yl-yl0)+ys0);
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end;
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function StoLx(xs: integer): real;
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begin
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Result := wl/ws*(xs-xs0)+xl0;
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end;
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begin // drawGraph
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xs0 := 0;
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ys0 := WindowHeight-1;
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ws := WindowWidth;
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hs := WindowHeight-1;
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xl0 := x1;
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wl := x2-x1;
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var min := real.MaxValue;
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var max := real.MinValue;
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var yi: array of real;
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SetLength(yi,ws+1);
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for var xi:=0 to ws do
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begin
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yi[xi] := f(StoLx(xi+xs0));
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if yi[xi]<min then
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min := yi[xi];
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if yi[xi]>max then
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max := yi[xi];
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end;
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yl0 := min;
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hl := -(max-min);
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// Нарисовать оси системы координат
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Line(0,LtoSy(0),ws,LtoSy(0));
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Line(LtoSx(0),0,LtoSx(0),hs);
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Pen.Color := clBlue;
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MoveTo(xs0,LtoSy(yi[0]));
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for var xi:=xs0+1 to xs0+ws do
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LineTo(xi,LtoSy(yi[xi-xs0]));
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end;
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procedure Resize;
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begin
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ClearWindow;
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drawGraph(0,60,f);
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Redraw;
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end;
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begin
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LockDrawing;
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SetWindowCaption('График функции: масштабирование');
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drawGraph(0,60,f);
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Redraw;
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OnResize := Resize;
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end.
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