C # location accuracy

Question

I need more precision than integer locations when puttng controls in a form. Control.location seems to only support Point. Is there any work for this?

Point p = new point (100, 200); this.Location = p; // this works of course

PointF pF = new PointF (100.04f, 200.08f); this.Location = pF; // this does not work, of course, because Location expects Point not PointF

Is there any setting in the basic form or basic control that I can set for more accurate location?

Answer 1

You can use Windows Presentation Foundation (WPF) together with XAML (both work well in Visual Studio), which allows sub-pixel positioning of controls.

However, assuming you're using Windows Forms, not WPF, why would you ever need to install a control in a non-integer (sub-pixel) location?

Answer 2

No, the rendering control in WinForms is based on the principle of the pixel. There is a way that you can achieve sub-pixel positioning (without using WPF), but that will work on your part, and I'm really not sure why you need it.

The essence of the approach is to create a user control with a hidden instance of the control that you are trying to use funcily (possibly subpixels). You hook all the user control events so that they go to the hidden control, and after each event you call the DrawToBitmap hidden control DrawToBitmap to take a snapshot of the control. Then you use Graphics.DrawImage to copy the snapshot to the surface of the user control. DrawImage is not limited to pixels, so you can compensate for the image by less than a pixel to achieve the exact positioning you are looking for.

Warning: please do not actually do this, because there is no reason for this when you can just use WPF. This would be a great job, as “passing control events through” is not as simple as it seems. There's also a problem with focusing properly in this way, since an invisible control cannot be set in focus (I'm not even going to tell you what a terrible hacker solution is for this problem).

Update: It’s worth reviewing this decision about WPF - it’s perfect for what you are doing and will make your life a lot easier. I, as a rule, was unhappy with WPF, because I believe that although it is very powerful, it is essentially overpowered for the applications to which it is most often installed (namely, business applications for boring applications). In your case, though, it provides the granularity that you really require in your application.

If you are stuck in WinForms, however, your best approach is to write your own UserControl versions of the text editing elements that your application requires. At its core, a TextBox is just a square onto which you draw a border and some text. The .Net Graphics methods for this ( DrawRectangle and DrawString ) can have the coordinates of the drawing indicated in floating point.

There are tons of StackOverflow questions about custom owner controls and GDI + graphics.

Answer 3

Although GDI + is capable of floating point coordinate systems, Win32 (which Winforms is based on) is not. Secondly, it is recommended to move to WPF, which has an ubiquitous floating point coordinate system based on device-independent virtual pixels.

Answer 4

1 point is 1 pixel, and therefore maximum resolution is required.

That is why 0,0 cards to the left corner and 1,024 cards to the right, with a resolution of 1024x768