In WinForms Controls' 'Size and 'Location properties are integer only.
In WPF these properties use double.
The 'SizeF structure in WinForms System.Drawing is used almost always for special operations in the Paint Event.
However, if you are doing some re-sizing of Controls in WinForms and want increased accuracy based on ratios: calculate Float Type values before scaling, then convert the 'SizeF to 'Size (integer) to scale with:
float xRatio, yRatio;
xRatio = (float)(newFormSize.Width) / oldFormSize.Width;
yRatio = (float)(newFormSize.Height) / oldFormSize.Height;
SizeF newSize = new SizeF(xRatio * pictureBox1.Width, pictureBox1.Height * yRatio);
pictureBox1.Size = newSize.ToSize();
Complete code example on request: yes, using ratios like this does give more accurate scaling.