TextEllipsis.cs

/*
MIT License

Copyright (c) 2019 kiepng

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;


/// <summary>
/// Textを範囲内に収まるように省略して表示する
/// 省略表示させたいTextと一緒にアタッチする
/// </summary>
public class TextEllipsis : UIBehaviour
{
    private Text m_Text;

    protected override void Awake()
    {
        if (m_Text != null)
        {
            return;
        }

        m_Text = GetComponent<Text>();
        m_Text.RegisterDirtyLayoutCallback(DoEllipsis);
    }

    protected override void OnDestroy()
    {
        m_Text.UnregisterDirtyLayoutCallback(DoEllipsis);
    }


    /// <summary>
    /// 省略記号
    /// </summary>
    private static readonly string ELLIPSIS = "...";

    private void DoEllipsis()
    {
        if (!IsActive() || m_Text == null)
        {
            return;
        }

        if (!NeedsEllipsis(m_Text))
        {
            return;
        }

        TextGenerator generator = m_Text.cachedTextGenerator;
        TextGenerationSettings settings = m_Text.GetGenerationSettings(m_Text.rectTransform.rect.size);
        generator.Populate(m_Text.text, settings);
        string result = string.Empty;
        for (int i = 0; i < generator.characterCount; ++i)
        {
            string current = m_Text.text.Substring(i, 1);
            string next = string.Empty;
            if (i + 1 <= generator.characterCount)
            {
                next = m_Text.text.Substring(i + 1, 1);
            }

            var preferredWidth = GetPreferredWidth(result + current + next);
            if (IsOverSize(m_Text.rectTransform.rect.size.x, preferredWidth))
            {
                result += ELLIPSIS;
                break;
            }

            result += current;
        }

        m_Text.text = result;
    }

    private bool NeedsEllipsis(Text text)
    {
        return IsOverSize(text.rectTransform.rect.size.x, text.preferredWidth);
    }

    private bool IsOverSize(float textBoxWidth, float preferredWidth)
    {
        return textBoxWidth < preferredWidth;
    }

    private float GetPreferredWidth(string str)
    {
        var settings = m_Text.GetGenerationSettings(Vector2.zero);
        return m_Text.cachedTextGeneratorForLayout.GetPreferredWidth(str, settings) / m_Text.pixelsPerUnit;
    }
}