How to draw on a Window in WPF (best practice)?

Question

I am trying to write a small interactive game-like application, where I need to have a Draw method that's gonna draw on screen, but can't figure out how to structure the method for WPF.

If this was Winforms, I could use:

public void Draw (Graphics g) {  } 

But for a WPF Window, what should I have on it in the xaml (currently only have a Grid), and what should this Draw method receive as an argument?

First I want to do it like this to get it working, then I can think about how to make it more WPF, etc. But now I am more interested in getting this to work.

Answer 1

Typically, you "draw" in WPF in a completely different manner.

In Windows Forms/GDI, the graphics API is an immediate mode graphics API. Each time the window is refreshed/invalidated, you explicitly draw the contents using Graphics.

In WPF, however, things work differently. You rarely ever directly draw - instead, it's a retained mode graphics API. You tell WPF where you want the objects, and it takes care of the drawing for you.

The best way to think of it is, in Windows Forms, you'd say "Draw a line from X1 to Y1. Then draw a line from X2 to Y2. Then ...". And you repeat this every time you need to "redraw" since the screen is invalidated.

In WPF, instead, you say "I want a line from X1 to Y1. I want a line from X2 to Y2." WPF then decides when and how to draw it for you.

This is done by placing the shapes on a Canvas, and then letting WPF do all of the hard work.