GUIScaler.cs

// @source: https://gist.github.com/darktable/2018687#file-guiscaler-cs

using System;
using System.Collections;
using UnityEngine;



/// Usage:
/// 	(optional) Call GUIScaler.Initialize() in Start(), Awake() or OnEnable() (only needed once)
/// 	Call GUIScaler.Begin() at the top of your OnGUI() methods
/// 	Call GUIScaler.End() at the bottom of your OnGUI() methods
/// 
/// WARNING: If you don't match Begin() and End() strange things will happen.
public static class GUIScaler
{
	// 163 is the dpi of the 1st generation iPhone, a good base value.
	const float BASE_SCALE = 163.0f;
	
	static bool _initialized = false;
	
	static bool _isScaling = false;
	
	static float _scale = 1f;
	public static float scale {
		get { return _scale; }
	}
	
	static Matrix4x4 _restoreMatrix = Matrix4x4.identity;
	
	
	/// Initialize the GUI scaler with a specific scale.
	public static void Initialize(float scale)
	{
		if (_initialized)
			return;
		else
			_initialized = true;
		
		// scale will be 0 on platforms that have unknown dpi (usually non-mobile)
		if (scale == 0f) {
			return;
		}
		else {
			_scale = scale;
			_isScaling = true;
		}
	}
	
	/// Initialize the GUI scaler using the detected screen dpi.
	public static void Initialize()
	{
		Initialize(Screen.dpi / BASE_SCALE);
	}
	
	/// All GUI elements drawn after this will be scaled.
	public static void BeginScale()
	{
		if (!_initialized)
			Initialize();
		
		if (!_isScaling)
			return;
		
		_restoreMatrix = GUI.matrix;
		
		GUI.matrix = GUI.matrix * Matrix4x4.Scale(new Vector3(_scale, _scale, _scale));
	}
	
	/// Restores the default GUI scale.
	/// All gui elements drawn after this will not be scaled.
	public static void EndScale()
	{
		if (!_isScaling)
			return;
		
		GUI.matrix = _restoreMatrix;
	}
	
	public static void Scale(Action contentsBlock) {
		BeginScale();
		contentsBlock();
		EndScale();
	}
}