Question

the problem I am having it that if inside the UIView Draw override, I change the view frame size, drawing a rectangle is not working as expected.

If I change the view frame size outside of the Draw override, it works fine. Is this an expected behavior or is it a problem with monotouch only?

This is the code I am using:

    class ChildView : UIView
{
    public override void Draw (RectangleF rect)
    {

        base.Draw (rect);

        CGContext g = UIGraphics.GetCurrentContext();

        //adding 30 points to view height
        RectangleF rec = new RectangleF(this.Frame.Location,this.Frame.Size);
        rec.Height+=30;
        RectangleF rec_bounds = new RectangleF(0,0,rec.Width,rec.Height);
        this.Frame=rec;
        this.Bounds=rec_bounds;

        //drawing a red rectangle to the first half of view height
        UIColor.Red.SetFill();
        RectangleF _rect = new RectangleF(this.Bounds.Location,this.Bounds.Size);
        _rect.Height=_rect.Height/2;
        g.FillRect(_rect);

    }
}

However, the output of this code is this: (it should draw only 30 points red, but it draws 60 points)

Here is a link to download the project to reproduce this issue:
http://www.grbytes.com\downloads\RectangleDrawProblem.rar

Answer 1

Καλημέρα!

This behavior is expected. If you want to change the view’s frame inside the Draw override, do it before getting the current context. That is because the graphics context also has a size and that is the size of the view at the time you are retrieving it.

Also, there is no need to set both the Bounds and the Frame of the view. You can just set either of them in this case.