Just to give you an idea what Delphi can do, here is a plot of the ever popular sin(x). I have put enough information into the code comments so you can build the form. The PaintBox Paint Event takes care of the plotting.

573 Views
``````// draw a coordinate cross and plot the function y = sin(x)
// the Windows form is taken up by a PaintBox Component 440x688 pixels
// in the left upper corner is a Button titled "Plot sin(x)"
// Delphi 3.0    (vegaseat)

unit PlotFunctionz;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ExtCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
PaintBox1: TPaintBox;
procedure CalculateGraph;
procedure PaintBox1Paint(Sender: TObject);
procedure Button1Click(Sender: TObject);
procedure FormResize(Sender: TObject);
private
{ Private declarations }

public
{ Public declarations }
end;

var
Form1: TForm1;
FPoints: array [0..144] of TPoint;

implementation

{\$R *.DFM}

procedure TForm1.CalculateGraph;
var
xRangePixels, yRangePixels: Integer;
origin: TPoint;
i: Integer;
begin
{
calculate the sinus curve in the interval -2Pi..+2Pi,
with a resolution of 4Pi/144, as a series of points that
will be connected by a polyline. The graph is scaled to fit into
the paintbox. The origin of the coordinate system is the center
of the paintbox. The default windows coordinate system is inverted,
the Y axis points downward.
}
xRangePixels := (paintbox1.Width - 2) div 4; // pixels in Pi
yRangePixels := (paintbox1.Height - 2) div 2; // pixels in 1
origin       := Point(paintbox1.Width div 2, paintbox1.Height div 2);
interval     := 4.0 * Pi / 144.0;
for i := 0 to High(FPoints) do
begin
FPoints[i].X := origin.x + Round(radian * xRangePixels / Pi);
FPoints[i].Y := origin.y - Round(sin(radian) * yRangePixels);
end;
end;

procedure TForm1.PaintBox1Paint(Sender: TObject);
var
origin: TPoint;
xRangePixels, yRangePixels: Integer;
begin
with PaintBox1.Canvas do
begin
// Fill background in white
Brush.Color := clBtnFace;
Brush.Style := bsSolid;
Fillrect(paintbox1.BoundsRect);

// Paint a coordinate cross
origin    := Point(paintbox1.Width div 2, paintbox1.Height div 2);
Pen.Color := clBlack;
Pen.Style := psSolid;
Pen.Width := 1;
MoveTo(1, origin.Y);
LineTo(paintbox1.Width - 1, origin.y);
MoveTo(origin.x, 1);
LineTo(origin.x, paintbox1.Height - 1);

// Paint some tickmarks and label the axis
Font.Name    := 'Symbol';
Font.Size    := 8;
Font.Color   := clBlack;
xRangePixels := (paintbox1.Width - 2) div 4; { pixels in Pi }
yRangePixels := (paintbox1.Height - 2) div 2; { pixels in 1 }

// X axis
MoveTo(origin.x - 2 * xRangePixels, origin.y - 4);
LineTo(origin.x - 2 * xRangePixels, origin.y + 4);
TextOut(origin.x - 2 * xRangePixels + 2, origin.y + 2, '-2p');
MoveTo(origin.x - xRangePixels, origin.y - 4);
LineTo(origin.x - xRangePixels, origin.y + 4);
TextOut(origin.x - xRangePixels + 2, origin.y + 2, '-p');
MoveTo(origin.x + xRangePixels, origin.y - 4);
LineTo(origin.x + xRangePixels, origin.y + 4);
TextOut(origin.x + xRangePixels - 2 - TextWidth('p'), origin.y + 2, 'p');
MoveTo(origin.x + 2 * xRangePixels, origin.y - 4);
LineTo(origin.x + 2 * xRangePixels, origin.y + 4);
TextOut(origin.x + 2 * xRangePixels - 2 - TextWidth('2p'), origin.y + 2, '2p');

// Y axis
MoveTo(origin.x - 4, origin.y - yRangePixels);
LineTo(origin.x + 4, origin.y - yRangePixels);
TextOut(origin.x + 4, origin.y - yRangePixels, '1.0');
MoveTo(origin.x - 4, origin.y - yRangePixels div 2);
LineTo(origin.x + 4, origin.y - yRangePixels div 2);
TextOut(origin.x + 4, origin.y - (yRangePixels + TextHeight('1')) div 2, '0.5');
MoveTo(origin.x - 2, origin.y + yRangePixels div 2);
LineTo(origin.x + 2, origin.y + yRangePixels div 2);
TextOut(origin.x + 3, origin.y + (yRangePixels - TextHeight('1')) div 2, '-0.5');
MoveTo(origin.x - 2, origin.y + yRangePixels);
LineTo(origin.x + 2, origin.y + yRangePixels);
TextOut(origin.x + 3, origin.y + yRangePixels - TextHeight('1'), '-1.0');

//Paint the graph
Pen.Color := clBlue;
Polyline(FPoints);
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
CalculateGraph;
end;

// need this to get plot going
procedure TForm1.FormResize(Sender: TObject);
begin
CalculateGraph;
end;

end.``````