AnnotationLabel.cs

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

public class AnnotationLabel : MonoBehaviour {

    public Image textBackground;
    public Text myText;
    public InputField myInputField;
    public BoxCollider myBoxCollider;
    //Padding to top + bot edges of background
    private float padding = 0.0f;

    //Used to set Label when load from file
    public void setLabelText(string newLabel) {
        myText.text = newLabel;
        myInputField.text = newLabel;
        resizeLabel ();
    }

    public String getLabelText() {
        return myText.text;
    }

    //Called when you click on Text Label
    public void annotationLabelClicked() {
        myInputField.gameObject.SetActive (true);
        myInputField.ActivateInputField ();
        myInputField.Select ();
        myInputField.MoveTextEnd (true);
        textBackground.color = new Color (textBackground.color.r, textBackground.color.b, textBackground.color.b, 0.0f);
        myText.color = new Color (myText.color.r, myText.color.b, myText.color.b, 0.0f);
    }

    // called when vlue in input Field changed
    public void ValueChanged () {
        myText.text = myInputField.text;
        resizeLabel ();
    }

    //Called when User finishs editing Label
    public void  EditingFinished () {
        this.GetComponentInParent<Annotation> ().saveLabelChanges ();
        myInputField.gameObject.SetActive (false);
        textBackground.color = new Color (textBackground.color.r, textBackground.color.b, textBackground.color.b, 1.0f);
        myText.color = new Color (myText.color.r, myText.color.b, myText.color.b, 1.0f);
    }

    private void resizeLabel() {
        if(padding == 0.0f) {
            padding = textBackground.gameObject.GetComponent<VerticalLayoutGroup> ().padding.top
                + textBackground.gameObject.GetComponent<VerticalLayoutGroup> ().padding.bottom;
        }

        //calc height
        Canvas.ForceUpdateCanvases();
        float newHeight = myText.preferredHeight + padding;
        Vector2 resize = new Vector2 (this.gameObject.GetComponent<RectTransform> ().rect.width, newHeight);
        //resize objects
        this.gameObject.GetComponent<RectTransform>().sizeDelta = resize;
        myBoxCollider.size = new Vector3(myBoxCollider.size.x, newHeight, myBoxCollider.size.z);
        myInputField.gameObject.GetComponent<RectTransform> ().sizeDelta = resize;
    }
}