Unity InputFieldMod v1.0

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System.Collections;
using System.Text.RegularExpressions;

// InputFieldMod v1.0
// Thanks to:
// mjkkirschner https://github.com/mjkkirschner/XYZ-Visual-Programming/blob/master/Assets/UI/ExpandingInputField.cs
// zxkne http://answers.unity3d.com/questions/1195865/ui-scrollrect-mask-not-hiding-input-field-caret-an.html#answer-1309469

[ExecuteInEditMode]
[RequireComponent(typeof(InputField))]
[RequireComponent(typeof(LayoutElement))]
public class InputFieldMod : UIBehaviour {
    [Range(1,50)]
    public int textRows = 1;

    // optional scroll rect parent (manually linked)
    public ScrollRect scrollRect;
    RectTransform scrollRectTransform;
    RectTransform ScrollRectTransform { get { if (scrollRect && !scrollRectTransform) scrollRectTransform = scrollRect.GetComponent<RectTransform>(); return scrollRectTransform; } }

    // parent gameobjects
    CanvasScaler scaler;
    float ScaleFactor { get { if (!scaler) scaler = GetComponentInParent<CanvasScaler>(); return scaler ? scaler.scaleFactor : 1; } }
    HorizontalOrVerticalLayoutGroup parentLayout;
    HorizontalOrVerticalLayoutGroup ParentLayout { get { parentLayout = transform.parent.GetComponent<HorizontalOrVerticalLayoutGroup>(); return parentLayout; } }

    // current gameobject components
    LayoutElement inputElement;
    LayoutElement InputElement { get { if (!inputElement) inputElement = GetComponent<LayoutElement>(); return inputElement; } }
    InputField inputField;
    InputField InputField { get { if (!inputField) inputField = GetComponent<InputField>(); return inputField; } }
    RectTransform rect;
    RectTransform Rect { get { if (!rect) rect = GetComponent<RectTransform>(); return rect; } }

    // child gameobjects
    CanvasRenderer caret;

    // string replacers
    private Regex colorTags = new Regex("<[^>]*>");
    private Regex keyWords = new Regex("and |assert |break |class |continue |def |del |elif |else |except |exec |finally |for |from |global |if |import |in |is |lambda |not |or |pass |print |raise |return |try |while |yield |None |True |False ");
    private Regex operators = new Regex("<=|>=|!=");
    public Regex definedTriggers { get; set; }

    // register input field events on start
    protected override void Start() {
        InputField.onValueChanged.AddListener(new UnityEngine.Events.UnityAction<string>(ResizeInput));
        InputField.onEndEdit.AddListener(new UnityEngine.Events.UnityAction<string>(Highlight));
        InputField.onValueChanged.AddListener(new UnityEngine.Events.UnityAction<string>(RemoveTags));
    }

    #if UNITY_EDITOR
    Vector2 offsetMin;
    Vector2 offsetMax;
    int fontSize;
    int textRowsOld;
    Vector2 scrollSize;
    #endif

    void Update() {
        #if UNITY_EDITOR
        //(editor only) size adjustment if values have changed
        if (textRows <= 0) textRows = 1;
        if (offsetMin == Vector2.zero || offsetMin != InputField.textComponent.rectTransform.offsetMin ||
            offsetMax == Vector2.zero || offsetMax != InputField.textComponent.rectTransform.offsetMax ||
            fontSize == 0 || fontSize != InputField.textComponent.fontSize ||
            textRowsOld == 0 || textRows != textRowsOld) {

            fontSize = InputField.placeholder.GetComponent<Text>().fontSize = InputField.textComponent.fontSize;
            offsetMin = InputField.placeholder.rectTransform.offsetMin = InputField.textComponent.rectTransform.offsetMin;
            offsetMax = InputField.placeholder.rectTransform.offsetMax = InputField.textComponent.rectTransform.offsetMax;
            if (scrollRect && textRowsOld != textRows) Debug.LogError("INPUT FIELD MOD: Text rows has no effect while Scroll Rect linked.");
            textRowsOld = textRows;
            ResizeInput();
        }

        // (editor only) adapt size to scroll rect
        if (scrollRect && (scrollSize == Vector2.zero || scrollSize != ScrollRectTransform.rect.size)) {
            scrollSize = ScrollRectTransform.rect.size;
            ResizeInput();
        }
        #endif

        // fix text selection masking
        if (!caret) {
            Transform caretTransform = InputField.transform.Find(InputField.transform.name + " Input Caret");
            if (caretTransform) {
                Graphic graphic = caretTransform.GetComponent<Graphic>();
                if (!graphic) {
                    Image image = caretTransform.gameObject.AddComponent<Image>();
                    image.color = new Color(0, 0, 0, 0);
                }
            }
        }
    }

    // string operations
    public void Highlight(string text) {
        InputField.text = colorTags.Replace(InputField.text, @"");
        InputField.text = keyWords.Replace(InputField.text, @"<color=blue>$&</color>");
        InputField.text = operators.Replace(InputField.text, @"<color=red>$&</color>");
        if (definedTriggers != null) {
            InputField.text = definedTriggers.Replace(InputField.text, @"<color=green>$&</color>");
        }
        InputField.MoveTextEnd(false);
    }

    private void RemoveTags(string text) {
        InputField.text = colorTags.Replace(InputField.text, @"");
    }

    // get text padding (min max vertical offset for size calculation)
    float VerticalOffset { get { return InputField.placeholder.rectTransform.offsetMin.y - InputField.placeholder.rectTransform.offsetMax.y; } }


    // resize input field recttransform
    void ResizeInput() {
        ResizeInput(InputField.text);
    }

    void ResizeInput(string text) {
        // current text settings
        TextGenerationSettings settings = InputField.textComponent.GetGenerationSettings(InputField.textComponent.rectTransform.rect.size);
        settings.generateOutOfBounds = false;
        // current text rect height
        float currentHeight = InputField.textComponent.rectTransform.rect.height;
        // preferred text rect height
        float preferredHeight = (new TextGenerator().GetPreferredHeight(InputField.text, settings) / ScaleFactor) + VerticalOffset;
        float defaultHeight;

        // default text rect height (fit to scroll parent or expand to fit text)
        if (scrollRect) defaultHeight = ScrollRectTransform.rect.height;
        else defaultHeight = ((new TextGenerator().GetPreferredHeight("", settings) * textRows ) / ScaleFactor) + VerticalOffset;

        // force resize
        if (currentHeight < preferredHeight || currentHeight > preferredHeight) {
            if (preferredHeight > defaultHeight) {
                if (ParentLayout) {
                    InputElement.preferredHeight = preferredHeight;
                } else {
                    Rect.sizeDelta = new Vector2(Rect.rect.width, preferredHeight);
                }
            } else {
                if (ParentLayout) {
                    InputElement.preferredHeight = defaultHeight;
                } else {
                    Rect.sizeDelta = new Vector2(Rect.rect.width, defaultHeight);
                }
            }
        } else {
            if (ParentLayout) {
                InputElement.preferredHeight = defaultHeight;
            } else {
                Rect.sizeDelta = new Vector2(Rect.rect.width, defaultHeight);
            }
        }

        // update scroll rect position
        if (scrollRect) StartCoroutine(ScrollMax());
    }

    // update scroll rect position (after Layout was rebuilt)
    IEnumerator ScrollMax() {
        yield return new WaitForEndOfFrame();
        if (scrollRect != null) scrollRect.verticalNormalizedPosition = 0;
    }
}