如何使用 FireMonkey TCanvas.DrawXXX 方法?

How to use FireMonkey TCanvas.DrawXXX methods?

我尝试创建一个带有自定义可视化效果的表单,但我无法使用最简单的 TCanvas 绘图方法。在下面的示例中,我只能看到填充的矩形,但看不到直线和圆弧:

procedure TEditorPanel.FormPaint(Sender: TObject; Canvas: TCanvas; const ARect: TRectF);
var
  center, radius: TPointF;
  rect: TRectF;
begin
  with Canvas do
  begin
    Fill.Color := TAlphaColors.White;
    FillRect(RectF(0, 0, Width, Height), 0, 0, AllCorners, 1);

    center := PointF(200, 200);
    radius := PointF(40, 40);

    Stroke.Color := TAlphaColors.Red;
    Fill.Color := TAlphaColors.Blue;
    DrawLine(center, radius, 1);
    DrawArc(center, radius, 0, 90, 1);

    rect := RectF(10, 10, 100, 100);
    FillRect(rect, 0, 0, AllCorners, 100);
  end;
end;

我错过了什么?

如果您使用的是 Delphi 10.1 或更高版本 您应该将 Stroke.Kind 设置为 TBrushKind.Solid 以显示行,默认值在 None 中:

var
  center, radius: TPointF;
  rect: TRectF;
begin
  with Canvas do
  begin
    Fill.Color := TAlphaColors.White;
    FillRect(RectF(0, 0, Width, Height), 0, 0, AllCorners, 1);

    center := PointF(200, 200);
    radius := PointF(40, 40);

    Stroke.Kind := TBrushKind.Solid;
    Stroke.Color := TAlphaColors.Red;
    Fill.Color := TAlphaColors.Blue;
    DrawLine(center, radius, 1);
    DrawArc(center, radius, 0, 90, 1);

    rect := RectF(10, 10, 100, 100);
    FillRect(rect, 0, 0, AllCorners, 100);
  end;