WPFのInkCanvasで塗りつぶす - プログラムの事とか

f:id:puni-o:20161201111926j:plain

InkCanvasは線を描くものっぽくて閉じた領域の塗りつぶし、みたいなことは標準ではできなさそうでした

ということでとりあえず適当に塗りつぶすようにしていみます

塗りつぶす人

System.Windows.Ink.Strokeを継承してDrawCoreで塗りつぶすようにします

ソース

public class CustomInkCanvas : InkCanvas
{
protected override void OnStrokeCollected(InkCanvasStrokeCollectedEventArgs e)
{
    this.Strokes.Remove(e.Stroke);
    var newStroke = new FillStroke(e.Stroke.StylusPoints, e.Stroke.DrawingAttributes);
    this.Strokes.Add(newStroke);

    base.OnStrokeCollected(new InkCanvasStrokeCollectedEventArgs(newStroke));
}
}

public class FillStroke : Stroke
{
public FillStroke(StylusPointCollection stylusPoints) : base(stylusPoints)
{
}
public FillStroke(StylusPointCollection stylusPoints, DrawingAttributes drawingAttributes) : base(stylusPoints, drawingAttributes)
{
}

protected override void DrawCore(DrawingContext drawingContext, DrawingAttributes drawingAttributes)
{
    if (drawingContext == null)
    {
        throw new ArgumentNullException(nameof(drawingContext));
    }
    if (null == drawingAttributes)
    {
        throw new ArgumentNullException(nameof(drawingAttributes));
    }

    if (this.StylusPoints.Count < 3) return;

    var stroke = new Pen(Brushes.Blue, 2);
    stroke.Freeze();
    var fill = new SolidColorBrush(Color.FromArgb(0x80, 0x00, 0xff, 0xff));
    fill.Freeze();

    var streamGeometry = new StreamGeometry();
    using (var geometryContext = streamGeometry.Open())
    {
        geometryContext.BeginFigure(this.StylusPoints[0].ToPoint(), true, false);
        var points = new PointCollection();
        for (var i = 1; i < this.StylusPoints.Count; i++)
        {
            points.Add(this.StylusPoints[i].ToPoint());
        }
        geometryContext.PolyLineTo(points, true, false);
    }

    drawingContext.DrawGeometry(fill, stroke, streamGeometry);
}
}