BackColor is not changing even though conditions are met

Question

I am making a game using XNA and a part of the game involves collecting drops. I have this code below that detects intersection between the character and the item:

//Intersection Code, If the character intersects with the item while the item is showing, run below
if (alive && charRange.Intersects(itemRect))
{
   alive = false; //stop showing the item
   Inv.ItemGot(); //Call the ItemGot class, which adds the item to the inventory screen
}

Another class contains the ItemGot() method, and the code for that is below:

public void ItemGot()
{  // Called from the ItemList class...
   // Sets the background color to black when called
   btnItems[0] = new Panel();
   btnItems[0].BackColor = Color.Black;
}

Basically, when the character intersects with the item rectangle, the color of btnItems[0] should turn from CornflowerBlue (which I set up earlier) to Black. However, the color does not change when the method is called and I don't know why. My code seems to be correct and I've had peers confirm that for me.

Have you set a breakpoint in `ItemGot()` to confirm it's being called? — poy, Jan 05 '14 at 04:55
@Andrew Yes, `ItemGot()` is being called as btnItems[0] is filled — demiZe, Jan 05 '14 at 05:06
You initialize `btnItem[0]` in `ItemGot()`. Is `btnItem[0]` equal to `panel 1` ? — user3093781, Jan 05 '14 at 05:15
@user3093781 `btnItems[0]` **is** panel 1. Perhaps I should rephrase this: `btnItems[0]` 's color should change to `Black`. — demiZe, Jan 05 '14 at 05:18
You may need to add `btnItem[0]` to its parent control. For example, Form1.Controls.Add(btnItem[0]). — user3093781, Jan 05 '14 at 05:42
I added that, but still nothing happened. Could it be that you need an event handler for this to work? — demiZe, Jan 05 '14 at 15:30

poy · Answer 1 · 2014-01-05T21:09:11.100

0

You are creating a new Panel, but never using it. It's likely you don't want to create a new one because you said the color is already set to CornFlowerBlue.

So, if you already have a Panel setup... ensure you add it to the btnItems list. That way you can access it via btnItems[0].

edited Jan 05 '14 at 21:09

answered Jan 05 '14 at 14:14

poy

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I got rid of the `btnItems[0] = new Panel();` but now I'm getting a NullReferenceException. Thing is though, I already initialized the panel array in the constructor. – demiZe Jan 05 '14 at 15:20
I added details to my answer. – poy Jan 05 '14 at 21:09

BackColor is not changing even though conditions are met

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