TCanvasAngleArc (C++)

Description

The following example exercises TCanvas.AngleArc and illustrates graphically how the parameters are used in the construction of the arc section.

Code

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  Extended Sin, Cos;
  int X1 = StrToInt(Edit1->Text);
  int Y1 = StrToInt(Edit2->Text);
  Extended Radius = StrToInt(Edit3->Text);
  Extended StartAngle = StrToFloat(Edit4->Text);
  Extended SweepAngle = StrToFloat(Edit5->Text);
 
  Repaint();
  Canvas->Pen->Color = clDefault;
  Canvas->MoveTo(X1-Radius, Y1-Radius); // Bounding box of the circle
  Canvas->LineTo(X1+Radius, Y1-Radius);
  Canvas->LineTo(X1+Radius, Y1+Radius);
  Canvas->LineTo(X1-Radius, Y1+Radius);
  Canvas->LineTo(X1-Radius, Y1-Radius);
  Canvas->MoveTo(X1, Y1);
  SinCos(((StartAngle+SweepAngle)*2*M_PI)/360, Sin, Cos);  // Angle has to be radians
  Canvas->LineTo(X1+Floor(Radius*Cos), Y1-Floor(Radius*Sin)); // Sweep is relative to Start
  Canvas->MoveTo(X1, Y1);
  SinCos((StartAngle*2*M_PI)/360, Sin, Cos);
  Canvas->LineTo(X1+Floor(Radius*Cos), Y1-Floor(Radius*Sin));
  Canvas->Pen->Color = clRed;
  Canvas->AngleArc(X1, Y1, Radius, StartAngle, SweepAngle);
  Canvas->LineTo(300, 300);  // Show where AngleArc left the current position.
}

Uses

• Vcl.Graphics.TCanvas.AngleArc ( fr | de | ja )
• System.Math.SinCos ( fr | de | ja )