如何在形状控件中创建缩进，允许在缩进区域上绘制？

Question

我有一个自定义控件，我正在对其应用形状。该形状具有一个指针(类似于Skype中显示消息是接收消息或发送消息的消息指示符)，该指针位于左侧或右侧。

当指示器位于左侧时，控件按预期绘制，但当我将指示符放在右侧时，指示符被放置在控件的右边边界之外。

我想要的缩进，是画左边的“化身”。我还将在右边为时间戳添加另一个缩进。

为了让事情变得更清楚，这里给出了当前和客观行为的图像：

​

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我使用的代码如下：

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;



/*
public enum SkyeBubbleColors as Color {
    Right=Color.FromArgb( 229, 247, 253 ),
    Left=Color.FromArgb( 199, 237, 252 )
}
*/

public enum BubbleIndicatorEnum {
    Left,
    Right
}


public class MessageRow : Control, IDisposable {


    public MessageRow() {
        SetStyle( ControlStyles.AllPaintingInWmPaint|ControlStyles.OptimizedDoubleBuffer|ControlStyles.ResizeRedraw|ControlStyles.SupportsTransparentBackColor|ControlStyles.UserPaint, true );
        UpdateStyles();
        DoubleBuffered=true;
        try {
            base.BackColor=this.Parent.BackColor;
        } catch ( Exception ee ) {
            Console.WriteLine( ee.Message );
        }

    }

}

public class Message : Control, IDisposable {


    internal class RTB : RichTextBox {

        protected override void OnLinkClicked( LinkClickedEventArgs e ) {
            System.Diagnostics.Process.Start(e.LinkText);
        }

        public RTB() {
            BorderStyle = System.Windows.Forms.BorderStyle.None;
            BackColor = Color.Orange;
            ForeColor = Color.White;
            ReadOnly = false;
            this.Font=new Font( "Segoe UI", 10 );
            Text="";
            Anchor = AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top;
            ScrollBars = RichTextBoxScrollBars.None;
        }

    }

    private RTB _Text;

    private bool _TimestampVisible = false;

    private bool _AvatarVisible=false;
    private int _AvatarWidth { get; set; }
    private Image _Avatar;
    public Image Avatar { 
        get { return _Avatar; }
        set { 
            _Avatar = value;
            if ( _Avatar!=null ) {
                _Avatar = ResizeImage(value, 28, 28);
                _AvatarWidth=40;
            } else {
                _Avatar = value;
                _AvatarWidth = 0;
            }
        }
    }

    public bool AvatarVisible {
        get { return _AvatarVisible; }
        set { _AvatarVisible = value; }
    }

    public Message() {
        SetStyle( ControlStyles.AllPaintingInWmPaint|ControlStyles.OptimizedDoubleBuffer|ControlStyles.ResizeRedraw|ControlStyles.SupportsTransparentBackColor|ControlStyles.UserPaint, true );
        UpdateStyles();
        DoubleBuffered = true;
        _Text = new RTB();
        _Text.ContentsResized+=_Text_ContentsResized;
        _Text.Location = new Point(15+_AvatarWidth,5);
        _Text.Width = Width - (15+_AvatarWidth);
        this.Controls.Add( _Text );
        _Text.Visible = true;
        BubbleIndicator=BubbleIndicatorEnum.Left;
        try {
            base.BackColor=this.Parent.BackColor;
        } catch ( Exception ee ) {
            Console.WriteLine(ee.Message);
        }
        if ( _TimestampVisible ) {

        }
    }

    /// <summary>
    /// Resize the image to the specified width and height.
    /// </summary>
    /// <param name="image">The image to resize.</param>
    /// <param name="width">The width to resize to.</param>
    /// <param name="height">The height to resize to.</param>
    /// <returns>The resized image.</returns>
    private static Bitmap ResizeImage( Image image, int width, int height ) {
        var destRect=new Rectangle( 0, 0, width, height );
        var destImage=new Bitmap( width, height );

        destImage.SetResolution( image.HorizontalResolution, image.VerticalResolution );

        using ( var graphics=Graphics.FromImage( destImage ) ) {
            graphics.CompositingMode=CompositingMode.SourceCopy;
            graphics.CompositingQuality=CompositingQuality.HighQuality;
            graphics.InterpolationMode=InterpolationMode.HighQualityBicubic;
            graphics.SmoothingMode=SmoothingMode.HighQuality;
            graphics.PixelOffsetMode=PixelOffsetMode.HighQuality;

            using ( var wrapMode=new ImageAttributes() ) {
                wrapMode.SetWrapMode( WrapMode.TileFlipXY );
                graphics.DrawImage( image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode );
            }
        }

        return destImage;
    }

    void _Text_ContentsResized( object sender, ContentsResizedEventArgs e ) {
        _Text.Height = e.NewRectangle.Height;
        base.Height = _Text.Height + 10;
    }

    private BubbleIndicatorEnum _BubbleIndicator;

    public BubbleIndicatorEnum BubbleIndicator {
        get { return _BubbleIndicator; }
    set{
            _BubbleIndicator=value;
            if ( value==BubbleIndicatorEnum.Left ) {
                _Text.Location=new Point( 15+_AvatarWidth, 5 );
            } else {
                _Text.Location=new Point( 5+_AvatarWidth, 5 );
            }
            _Text.Width=Width-(20+_AvatarWidth);
            UpdateBubbleIndicator();
            _Text.Refresh();
            Invalidate();
        }
    }

    protected override void OnRegionChanged( EventArgs e ) {
        base.OnRegionChanged( e );
    }

    protected override void OnLocationChanged( EventArgs e ) {
        base.OnLocationChanged( e );
        try {
            base.BackColor=this.Parent.BackColor;
        } catch ( Exception ee ) {
            Console.WriteLine( ee.Message );
        }
    }

    public override string Text {
        get {
            return _Text.Text;
        }
        set {
            _Text.Text = value;
            //_Text.RenderEmotes();
        }
    }

    public override Color ForeColor {
        get {
            return _Text.ForeColor;
        }
        set {
            _Text.ForeColor=value;
        }
    }

    public override Font Font {
        get {
            return _Text.Font;
        }
        set {
            _Text.Font=value;
        }
    }

    private Color _BubbleColor = Color.Orange;

    public Color BubbleColor {
        get {
            return _BubbleColor;
        }
        set {
            _BubbleColor=value;
            _Text.BackColor=value;
            _Text.Refresh();
            Invalidate();
        }
    }


    private GraphicsPath Shape = new GraphicsPath();

    protected override void OnResize( EventArgs e ) {
        base.OnResize( e );
        UpdateBubbleIndicator();
    }

    private void UpdateBubbleIndicator() {
        _Text.BackColor=_BubbleColor;
        Shape=new GraphicsPath();

        if ( BubbleIndicator==BubbleIndicatorEnum.Left ) {
            Shape.AddArc( 9+_AvatarWidth, 0, 10, 10, 180, 90 );
            Shape.AddArc( (Width+_AvatarWidth)-11, 0, 10, 10, -90, 90 );
            Shape.AddArc( ( Width+_AvatarWidth )-11, Height-11, 10, 10, 0, 90 );
            Shape.AddArc( 9+_AvatarWidth, Height-11, 10, 10, 90, 90 );
        } else {
            Shape.AddArc( 0, 0, 10, 10, 180, 90 );
            Shape.AddArc( Width-18, 0, 10, 10, -90, 90 );
            Shape.AddArc( Width-18, Height-11, 10, 10, 0, 90 );
            Shape.AddArc( 0, Height-11, 10, 10, 90, 90 );
//              Shape.AddArc( 0+_AvatarWidth, 0, 10, 10, 180, 90 );
//              Shape.AddArc( ( Width+_AvatarWidth )-18, 0, 10, 10, -90, 90 );
//              Shape.AddArc( ( Width+_AvatarWidth )-18, Height-11, 10, 10, 0, 90 );
//              Shape.AddArc( 0+_AvatarWidth, Height-11, 10, 10, 90, 90 );
        }

        Shape.CloseAllFigures();
        _Text.Width=Width-(20+_AvatarWidth);
    }



    protected override void OnPaint( PaintEventArgs e ) {

        Point[] p;

        if ( BubbleIndicator==BubbleIndicatorEnum.Left ) {
            p= new Point[] {
                    new Point(9+_AvatarWidth, 9),
                    new Point(0+_AvatarWidth, 15),
                    new Point(9+_AvatarWidth, 20)
            };
        } else {
            p = new Point[] {
                    new Point(Width - 8, 9),
                    new Point(Width, 15),
                    new Point(Width - 8, 20)
            };
        }

        SuspendLayout();
        e.Graphics.Clear( BackColor );
        e.Graphics.SmoothingMode=SmoothingMode.HighQuality;
        e.Graphics.PixelOffsetMode=PixelOffsetMode.HighQuality;
        e.Graphics.FillPath( new SolidBrush( _BubbleColor ), Shape );
        e.Graphics.FillPolygon( new SolidBrush( _BubbleColor ), p );
        e.Graphics.DrawPolygon( new Pen( new SolidBrush( _BubbleColor ) ), p );
        e.Graphics.InterpolationMode=InterpolationMode.HighQualityBicubic;
        if ( _AvatarWidth>0&&_AvatarVisible==true&&_Avatar!=null ) {
            e.Graphics.DrawImageUnscaled( _Avatar, 0, 0);
            e.Graphics.DrawImageUnscaled( new Bitmap( this.Width-_AvatarWidth, this.Height ), _AvatarWidth, 0 );
        } else {
            e.Graphics.DrawImageUnscaled( new Bitmap( this.Width, this.Height ), 0, 0 );
        }
        base.OnPaint( e );
        ResumeLayout();
    }

}

请记住，这些框的高度取决于内容，无论控件的高度如何，指示器都应该是相同的大小和第一行。这个功能已经到位，但我觉得有必要提及，因为我相信缩放形状或绘图艺术会导致指针在位置和宽度/高度上不一致或变形。

如果你注意到，这个区域确实是完美地夹在左边，并且像图像中的第一个例子所示的那样是可画的，但是如果我移动到右边的指针，由于某种原因，我不能再剪辑左边了，这是我的问题的核心。

刚刚注意到，我标记为“正确”的图像中的棕色指示符实际上几乎是正确的。信息气泡的右侧应该有圆角，如红色和橙色信息的左侧所示。

Answer 1

我会改变这些地方：

   if ( BubbleIndicator==BubbleIndicatorEnum.Left ) {
        Shape.AddArc( 9+_AvatarWidth, 0, 10, 10, 180, 90 );
        Shape.AddArc( (Width/*+_AvatarWidth*/)-11, 0, 10, 10, -90, 90 ); // !!
        Shape.AddArc( (Width/*+_AvatarWidth*/ )-11, Height-11, 10, 10, 0, 90 ); //!!

和

    } else {
        Shape.AddArc( _AvatarWidth, 0, 10, 10, 180, 90 ); //!!
        Shape.AddArc( Width-18, 0, 10, 10, -90, 90 );
        Shape.AddArc( Width-18, Height-11, 10, 10, 0, 90 );
        Shape.AddArc(  _AvatarWidth, Height-11, 10, 10, 90, 90 ); //!!

请注意，这是未经测试的！