If you’re using Delphi XE5 Firemonkey to do any kind of drawing on TCanvas with DrawLine you may have run into this issue. The problem is that when you draw a one pixel line what you end up with doesn’t appear as a one pixel line. I believe this issue exists on both Android and IOS. Roman Yankovsky has a blog post demonstrating the problem and showing the solution. Here is an example of DrawLine where the problem manifests:
Canvas.DrawLine(PointF(50 + I * 25, 0), PointF(50 + I * 25, ClientHeight), 1);
And here is the an example of DrawLine with the extra code that fixes the problem:
Canvas.DrawLine(PointF(50 + I * 25 – (Canvas.Stroke.Thickness / 2), 0),
PointF(50 + I * 25 – (Canvas.Stroke.Thickness / 2), ClientHeight), 1);
Roman has much more comprehensive example code on his blog and even a second method for correcting the problem.
Head over to read the full blog post about correcting DrawLine on TCanvas.
