[C#] TextBoxRenderer

找資料時發現原來有 TextBoxRenderer 內建 Render class，用官方文章範例來了解如何使用，該範例重點

• 使用 TextBxRender.DrawTextBox 繪製 TextBox
• 直接新增 ComboBox 並把 TextFormatFlags 放進去當成選項
• 使用 ComboBox 選擇 TextFormatFlags 來變化、觀察 TextBox 內文字效果 

using System;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;

namespace TextBoxRendererSample
{
    public class CustomTextBox : Control
    {
        private TextFormatFlags _textFlags = TextFormatFlags.EndEllipsis;
        private ComboBox _comboBox = new ComboBox();
        private Rectangle _textBorder = new Rectangle();
        private Rectangle _textRectangle = new Rectangle();

        public CustomTextBox() : base()
        {
            this.Location = new Point(10, 10);
            this.Size = new Size(300, 200);
            this.Font = SystemFonts.IconTitleFont;

            TextBoxInit();
            ComboBoxInit();
        }

        private void TextBoxInit()
        {
            _textBorder.Location = new Point(10, 10);
            _textBorder.Size = new Size(200, 50);
            _textRectangle.Location = new Point(_textBorder.X + 2, _textBorder.Y + 2);
            _textRectangle.Size = new Size(_textBorder.Size.Width - 4, _textBorder.Height - 4);
        }

        private void ComboBoxInit()
        {
            _comboBox.Location = new Point(10, 100);
            _comboBox.Size = new Size(150, 20);
            _comboBox.DropDownStyle = ComboBoxStyle.DropDownList;

            // 把 TextFormatFlags Enum 塞進 ComboBox 內去
            _comboBox.Items.AddRange(Enum.GetNames(typeof(TextFormatFlags)).ToArray());

            _comboBox.SelectedIndex = _comboBox.FindStringExact(nameof(TextFormatFlags.EndEllipsis));
            _comboBox.SelectionChangeCommitted += ComboBox_SelectionChangeCommitted;
            this.Controls.Add(_comboBox);
        }


        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            // TextBoxRenderer class can be used to draw a text box with visual styles.
            if (TextBoxRenderer.IsSupported)
            {
                this.Parent.Text = "CustomTextBox Enabled";
                this.Text = "This is a long sentence that will exceed the text box bounds";

                // 繪製 TextBox 重點
                TextBoxRenderer.DrawTextBox(
                    e.Graphics,
                    _textBorder,
                    this.Text,
                    this.Font,
                    _textRectangle,
                    _textFlags,
                    TextBoxState.Normal);
            }
            else
            {
                this.Parent.Text = "CustomTextBox Disabled";
            }
        }

        private void ComboBox_SelectionChangeCommitted(object sender, EventArgs e)
        {
            if (Enum.TryParse(_comboBox.Text, out TextFormatFlags flags) == false)
                return;

            this._textFlags = flags;
            Invalidate();
        }
    }
}

把自訂控件拖曳至 Form 內執行，下面為執行結果截圖，除了可以看見繪製出來的 TextBox 外，還可以觀察 TextFormatFlags 文字效果

TextFormatFlags.Default 效果：該範例設計就是文字要超過 TextBox

TextFormatFlags.NoClipping 效果：文字超過 TextBox

TextFormatFlags.EndEllipsis 效果：文字碰上 TextBox 邊界，會以 ... 來表示截斷文字

   

TextFormatFlags.WordBreak 效果：文字折行

感覺 TextFormatFlags 文字效果最後變成文章重點，哈

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