c# - WPF InkCanvas : Draw line with DynamicRenderer

Question

我正在使用 InkCanvas 在 WPF 中编写基本图形编辑器。我制作了一些自定义形状(继承自 Stroke)。当我在 InkCanvas 上画线时，我会取第一个点和最后一个点并画一条线。这很好用，但现在我不喜欢默认的“笔划”，所以我决定重写 DynamicRenderer 以实时渲染线条。

问题是，DynamicRenderer 从原点到笔划的每个点画线，我显然不希望那样，因为它使 "fan"代替线路。

有我的自定义代码，如果可能的话，我正在寻找从原点到最后一点画线的解决方案。

class LineRenderer : DynamicRenderer
{
    private Point firstPoint;
    private Pen pen = new Pen(new SolidColorBrush(Colors.Gray),1);

    public LineRenderer()
    {
        firstPoint = new Point(double.PositiveInfinity, double.PositiveInfinity);
    }

    protected override void OnStylusDown(RawStylusInput rawStylusInput)
    {
        firstPoint = new Point(rawStylusInput.GetStylusPoints().First().ToPoint().X, rawStylusInput.GetStylusPoints().First().ToPoint().Y);
        base.OnStylusDown(rawStylusInput);
    }

    protected override void OnDraw(DrawingContext drawingContext,
                                   StylusPointCollection stylusPoints,
                                   Geometry geometry, Brush fillBrush)
    {
        drawingContext.DrawLine(pen, firstPoint, stylusPoints.First().ToPoint());
    }

    protected override void OnStylusUp(RawStylusInput rawStylusInput)
    {
        firstPoint = new Point(double.PositiveInfinity, double.PositiveInfinity);
        base.OnStylusUp(rawStylusInput);
    }
}

Answer 1

这已经很晚了。为了避免在绘制笔划时出现“扇形”，试试这个:

protected override void OnDraw(DrawingContext drawingContext,
                               StylusPointCollection stylusPoints,
                               Geometry geometry, Brush fillBrush)
        {
            if (!_isManipulating)
            {
                _isManipulating = true;
                StylusDevice currentStylus = Stylus.CurrentStylusDevice;
                this.Reset(currentStylus, stylusPoints);
            }
            _isManipulating = false;

            var pen = new Pen(brush, 2);
            drawingContext.DrawLine(pen, startPoint,stylusPoints.First().ToPoint());
       }


protected override void OnStylusDown(RawStylusInput rawStylusInput)
        {
            StylusPointCollection y = rawStylusInput.GetStylusPoints();
            startPoint = (Point)y.First();

            // Allocate memory to store the previous point to draw from.
            prevPoint = new Point(double.NegativeInfinity, double.NegativeInfinity);
            base.OnStylusDown(rawStylusInput);
        }

这里的技巧是使用 DynamicRenderer.Reset ，其中:

Clears rendering on the current stroke and redraws it.

重绘将重新进入 OnDraw 方法，因此 _isManipulating 提供了一个简单的标志来停止循环。