Fix Gamepad crash when platform doesn't support the amount

[harry-cpp]

Instead of throwing an exception we should just return an empty state, this also makes the style of this more XNAish.

http://community.monogame.net/t/monogame-3-5-gamepad-getstate/7288

[tomspilman]

Hopefully no one depends on the exception to detect the maximum supported gamepad. At least we added GamePad.MaximumGamePadCount for that.

[harry-cpp]

Hopefully no one depends on the exception to detect the maximum supported gamepad. At least we added GamePad.MaximumGamePadCount for that.

Xna didn't call a crash when the gamepad was not supported(Windows Phone), but instead just returned an empty state, right?

[tomspilman]

but instead just returned an empty state, right?

Well... it did return a gamepad state, but just for the back button detection.

Don't know what happened if you asked for the second gamepad.

[harry-cpp]

Don't know what happened if you asked for the second gamepad.

From googling around I am 95% sure it returned an empty state.

[harry-cpp]

@dellis1972 @KonajuGames What do you think on this?

[tomspilman]

So I did a little research on this before merging it.

Under XNA a disconnected gamepad does not throw any exception. It just returns a disconnected state.

If you are using XNA on WP7 GamePad.GetState(PlayerIndex.Two) also does not throw an exception. It just reports it as disconnected. In fact on WP7 you can call GamePad.GetState((PlayerIndex)100) and it just returns a disconnected state.

The only case where GamePad.GetState() throws an exception is on the PC when you pass an invalid enum value. So GamePad.GetState((PlayerIndex)100) on the PC throws and exception about an invalid enum value.

So my conclusions from this:

This PR is fine... we shouldn't throw exceptions from the indexed versions of the GamePad.GetState/GetCapabilities/SetVibration when referencing more gamepads than supported on the platform. I will merge this shortly.

However we should consider following up this PR with another for the enum versions of these functions which validates that a correct PlayerIndex enum is passed it and throw an argument exception otherwise. The enum versions should be strict and behave like XNA on the desktop.

[tomspilman]

Thanks @cra0zy !