剪切工具滞后荧光笔

我尝试在 C# Winforms 中创建荧光笔。我使用的大部分代码都在这里像截图工具一样突出显示效果但当我尝试画得太快时，它就会滞后。不确定我做错了什么。这是我尝试过的。

private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
    Bitmap bmp = (Bitmap)pictureBox1.Image;
    using (Graphics g = Graphics.FromImage(pictureBox1.Image))
    {
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
        IntPtr hBMP = bmp.GetHbitmap();
        IntPtr bDC = g.GetHdc();
        IntPtr mDC = CreateCompatibleDC(bDC);
        IntPtr oDC = SelectObject(mDC, hBMP);

        int useColor = System.Drawing.ColorTranslator.ToWin32(brush.Color);
        IntPtr pen = CreatePen(PS_SOLID, _w, (uint)useColor);
        IntPtr xDC = SelectObject(mDC, pen);
        SetROP2(mDC, R2_MASKPEN);
        Rectangle dest = new Rectangle(currentX - _x, currentY - _y, _w, _h);
        Rectangle(mDC, dest.Left, dest.Top, dest.Right, dest.Bottom);
        SetROP2(mDC, R2_COPYPEN);

        BitBlt(bDC, 0, 0, bmp.Width, bmp.Height, mDC, 0, 0, SRCCOPY);
        SelectObject(mDC, xDC);
        DeleteObject(pen);
        g.ReleaseHdc(bDC);
        SelectObject(mDC, oDC);
        DeleteDC(mDC);
        DeleteObject(hBMP);
    }
}

What I'm trying to do is:

Edit

bool draw = false;
int currentX = 0;
int currentY = 0;

//Rectangle width/height
int _w = 6;
int _h = 18

//These are just to center the cursor according to the width and height of rectangle.
int _x = 3; //(half of _w)
int _y = 9; //(half of _h)

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    draw = true;
}

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left && draw == true)
    {
        currentX = e.X;
        currentY = e.Y;
        pictureBox1.Invalidate();
    }
}

您需要将点存储在列表中，然后为了平滑绘图，使用基于这些点绘制曲线DrawCurve。此外，您还需要设置一支具有适当设置（例如圆形）的宽笔LineJoin, StartCap and EndCap，然后你可以得到如下的高亮图：

List<List<Point>> Lines = new List<List<Point>>();
bool drawing = false;
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    Lines.Add(new List<Point>());
    Lines.Last().Add(e.Location);
    drawing = true;
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (drawing) { Lines.Last().Add(e.Location); pictureBox1.Invalidate(); }
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
    if (drawing)
    {
        this.drawing = false;
        Lines.Last().Add(e.Location);
        pictureBox1.Invalidate();
    }
}
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
    using (var pen = new Pen(Color.FromArgb(150, Color.Yellow), 30)
    {
        LineJoin = System.Drawing.Drawing2D.LineJoin.Round,
        StartCap = System.Drawing.Drawing2D.LineCap.Round,
        EndCap = System.Drawing.Drawing2D.LineCap.Round,
    })
        foreach (var item in Lines)
            e.Graphics.DrawCurve(pen, item.ToArray());
}