How to make select method in custom draw control?

Question

I am creating a control extend from pictureBox and only use GDI to paint the content. I want to make select method( Ctrl + A) to select content. How to do that??

Answer 1

I'd store my selection in a Rect (assuming you only want to use square selections).

When hitting Ctrl+A, you'd just do something like selectionRect = new Rect(0, 0, bitmap.Width, bitmap.Height);

Answer 2

I want to change color of selected region to show that it's selected. My solution is changing each pixel colors of pictureBox, but it's very slow. I try using LockBits,it's good if Idon't calc color for each pixel. How to resolve the problem?