Draws an arc on the image along the perimeter of the ellipse bounded by the specified rectangle.
procedure Arc(X1, Y1, X2, Y2, X3, Y3, X4, Y4: Integer);
The following lines of code draw the top quarter of an arc bounded by the current window:procedure TForm1.FormPaint(Sender: TObject);
var
R: TRect;
begin
R := GetClientRect; {Gets the boundaries of the current window}
Canvas.Arc(R.Left, R.Top, R.Right, R.Bottom, R.Right, R.Top, R.Left, R.Top);
end;
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procedure Arc(X1, Y1, X2, Y2, X3, Y3, X4, Y4: Integer);
The following lines of code draw the top quarter of an arc bounded by the current window:procedure TForm1.FormPaint(Sender: TObject);
var
R: TRect;
begin
R := GetClientRect; {Gets the boundaries of the current window}
Canvas.Arc(R.Left, R.Top, R.Right, R.Bottom, R.Right, R.Top, R.Left, R.Top);
end;
多看看帮助啊!
多谢两位指点,
我是想不清如何转换,
canvas.arc的用法我知道,
不过我是想实现已知始点、终点和中间某点来画出这条弧线
(XA-X0)^2+(YA-Y0)^2=(XB-X0)^2+(YB-Y0)^2=(XC-X0)^2+(YC-Y0)^2
将三点坐标代入,可以求出X0,Y0,再对((XA-X0)^2+(YA-Y0)^2)开方可得圆半径r
余下的不要我说了吧!