Why is FMX's DrawLine() function not working properly?

I'm using C++Builder 11 Community Edition on a Windows 10 PC.

I'm trying to draw lines. When I make a VCL app, it all works fine, but I want to use FMX to take advantage of the GPU.

The FMX code is giving me blurred lines with Stroke->Thickness set to 1.0. I need the line thickness to be 1 pixel wide. This will eventually be a program that draws a bar graph.

This is the VCL code:

void __fastcall TForm1::Button1Click(TObject *Sender)
{
	Canvas->Pen->Width = 1;
	Canvas->Pen->Color = (Graphics::TColor) clBlack;

	Canvas->MoveTo(100,100);
	Canvas->LineTo(500,100);
	Canvas->MoveTo(100,101);
	Canvas->LineTo(300,101);
	Canvas->MoveTo(100,102);
	Canvas->LineTo(500,102);
}

This is the FMX code:

void __fastcall TForm1::Button1Click(TObject *Sender)
{
	Canvas->BeginScene();
//	Canvas->Clear(TAlphaColorRec::Blue);

	Canvas->Stroke->Color = TAlphaColorRec::Black;
	Canvas->Stroke->Thickness = 1.0;
	Canvas->DrawLine(TPointF(100,100), TPointF(500,100), 1.0);
	Canvas->DrawLine(TPointF(100,101), TPointF(300,101), 1.0);
	Canvas->DrawLine(TPointF(100,102), TPointF(500,102), 1.0);

	Canvas->EndScene();
}

I've tried different opacities and line thicknesses. If I repeat the line draw function 10 times, it looks better, but this is obviously not the way to go!

Can anybody help with this?

The solution is to offset all coordinates by half a pixel so that it's drawing from the center of the pixel rather than at a pixel boundary. This ensures that the anti-aliased graphics doesn't blend the pixels over a boundary. You could also set the Form's Quality property to HighPerformance to disable anti-aliasing, but that may negatively affect graphics quality on other parts of the form where you may want to keep anti-aliasing.

The following works with Quality set to HighQuality

void __fastcall TForm1::Button1Click(TObject *Sender)
{
    Canvas->BeginScene();
//  Canvas->Clear(TAlphaColorRec::Blue);

    Canvas->Stroke->Color = TAlphaColorRec::Black;
    Canvas->Stroke->Thickness = 1.0;
    Canvas->DrawLine(TPointF(100.5,100.5), TPointF(500.5,100.5), 1.0);
    Canvas->DrawLine(TPointF(100.5,101.5), TPointF(300.5,101.5), 1.0);
    Canvas->DrawLine(TPointF(100.5,102.5), TPointF(500.5,102.5), 1.0);

    Canvas->EndScene();
}