Change button text color on click depending on boolean-CodePudding

General Info
Working on a simple 2D Gui for a game mod to enable / disable mod functions through buttons.

The problem
When a user clicks a button, the text changes from "function: off" to "function: on" and visa versa. It uses a simple boolean to accomplish this. To make it more clear to the user which functions have been enabled / disabled, I'm trying to change the text color just as well.

What I've tried myself to accomplish this
Doing a bit of research myself, it became clear to me that the color of text on a button can be changed as follows:

private static GUIStyle enabledText;
private static GUIStyle disabledText;

public static void Start()
{
    enabledText = new GUIStyle(GUI.skin.button);
    enabledText.normal.textColor = Color.green;

    disabledText = new GUIStyle(GUI.skin.button);
    disabledText.normal.textColor = Color.red;
}

Then wherever needed:

GUILayout.Button("Label", style);

Here is an example of how I implement a button:

if (GUILayout.Button("God Mode: "   (s_isGodMode ? "On" : "Off")))
{
    s_isGodMode = !s_isGodMode;
}

So putting that and the research done earlier together, this would be the result:

if (GUILayout.Button("God Mode: "   (s_isGodMode ? "On" : "Off"), (s_isGodMode ? enabledText : disabledText)))
{
    s_isGodMode = !s_isGodMode;
}

Which compiles fine and without any errors or warnings. However, when trying to load it in, I'm presented with:

[Error : Unity Log] NullReferenceException: Object reference not set to an instance of an object
Stack trace:
UnityEngine.GUILayoutUtility.DoGetRect (UnityEngine.GUIContent content, UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options) (at :0)
UnityEngine.GUILayoutUtility.GetRect (UnityEngine.GUIContent content, UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options) (at :0)
UnityEngine.GUILayout.DoButton (UnityEngine.GUIContent content, UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options) (at :0)
UnityEngine.GUILayout.Button (System.String text, UnityEngine.GUIStyle style, UnityEngine.GUILayoutOption[] options) (at :0)
QualityOfLife.QOL.Core.Cheats.DisplayGUI () (at <98e4be18d16b445790f620c81671da54>:0)
QualityOfLife.QOL.EntryPoint.ValheimToolerWindow (System.Int32 windowID) (at <98e4be18d16b445790f620c81671da54>:0)
UnityEngine.GUILayout LayoutedWindow.DoWindow (System.Int32 windowID) (at :0)
UnityEngine.GUI.CallWindowDelegate (UnityEngine.GUI WindowFunction func, System.Int32 id, System.Int32 instanceID, UnityEngine.GUISkin _skin, System.Int32 forceRect, System.Single width, System.Single height, UnityEngine.GUIStyle style) (at :0)

The resulting menu is just a blank rectangle. Removing the second parameter to change the GUI button text color resolves the problem and makes it work perfectly fine again. What exactly am I doing wrong and how should I resolve the issue?

CodePudding user response：

You have:

public static void Start()

why is that static? Is your class a MonoBehaviour? Should not be static, for Unity to find/call this function (I think*). Just in case that never gets called, your enabledText and disabledText variables will not be initialized, and that will cause the null reference exception.

* you can make Start() async or make it return IEnumerator, but I don't think static works, because it should be called per object, not globally. https://docs.unity3d.com/ScriptReference/MonoBehaviour.Start.html