我正在尝试制作一种橡皮擦工具,该工具可以擦除GraphicsPath
中的点。到目前为止,我的代码允许用户在表单上绘画,并且“擦除”按钮应该擦除GraphicsPath
的前20个点。它可以一直工作到绘制了两个可区分的图纸,然后按下“擦除”按钮-如图中所示,两个图纸连接在一起。我怀疑本身会关闭(连接每个点)。
有没有办法防止GraphicsPath
连接每个点?
这是我的完整代码。我认为最相关的部分是底部的功能。
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Windows.Forms;
namespace Cartographer
{
public partial class testform : Form
{
private GraphicsPath _drawingPath = new GraphicsPath();
private Point lastMouseLocation;
private bool drawing = false;
public testform()
{
InitializeComponent();
}
private void testform_Load(object sender, EventArgs e)
{
this.Paint += Testform_Paint;
this.MouseMove += Testform_MouseMove;
this.DoubleBuffered = true;
}
private void Testform_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
drawing = true;
_drawingPath.AddLine(lastMouseLocation, e.Location);
Invalidate();
}
if (e.Button == MouseButtons.None && drawing)
{
drawing = false;
_drawingPath.StartFigure(); // problem is not due to this line
}
lastMouseLocation = e.Location;
}
private void Testform_Paint(object sender, PaintEventArgs e)
{
e.Graphics.InterpolationMode = InterpolationMode.HighQualityBilinear;
e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
e.Graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
using (SolidBrush b = new SolidBrush(Color.Blue))
using (Pen p = new Pen(b, 51))
{
p.StartCap = System.Drawing.Drawing2D.LineCap.Round;
p.EndCap = System.Drawing.Drawing2D.LineCap.Round;
p.Alignment = System.Drawing.Drawing2D.PenAlignment.Inset;
e.Graphics.DrawPath(p, _drawingPath);
}
using (SolidBrush b = new SolidBrush(Color.LightGreen))
using (Pen p = new Pen(b, 50))
{
p.StartCap = System.Drawing.Drawing2D.LineCap.Round;
p.EndCap = System.Drawing.Drawing2D.LineCap.Round;
p.Alignment = System.Drawing.Drawing2D.PenAlignment.Inset;
e.Graphics.DrawPath(p, _drawingPath);
}
}
private void btnErase_Click(object sender, EventArgs e)
{
List<PointF> ptsList = new List<PointF>();
for (int i = 0; i < 20; i++)
{
ptsList.Add(_drawingPath.PathData.Points[i]);
}
_drawingPath = ErasePointsFromPath(_drawingPath, ptsList.ToArray<PointF>());
this.Invalidate();
}
private GraphicsPath ErasePointsFromPath(GraphicsPath path, PointF[] toRemove)
{
PointF[] newPoints = path.PathData.Points.Except<PointF>(toRemove).ToArray<PointF>();
byte[] types = new byte[newPoints.Length];
for (int i = 0; i < newPoints.Length; i++)
{
types[i] = 1;
}
GraphicsPath ret = new GraphicsPath(newPoints, types);
//ret.SetMarkers();
return ret;
}
}
}
这就是发生的情况。图中的两条圆形线应该是分开的,并且不由该对角线连接。
最佳答案
当您从路径中删除点时,您可以通过将其复制到新路径中来进行删除(不包括要删除的点)。但是,您也不会从第一条路径复制相应的点类型信息。相反,无论出于何种原因,您都将所有点类型重置为1。这会丢失有关路径中每个图形的起始位置的信息。因此,发生的事情是新路径看到了一个相互关联的图形,它解释了您所看到的。
如果要删除路径的前n个点,则可以尝试执行以下操作:
private void btnErase_Click(object sender, EventArgs e)
{
int numberOfPointsToErase = 20;
if (_drawingPath.PointCount > numberOfPointsToErase)
{
_drawingPath = new GraphicsPath(
_drawingPath.PathPoints.Skip(numberOfPointsToErase).ToArray(),
_drawingPath.PathTypes.Skip(numberOfPointsToErase).ToArray()
);
}
else
{
_drawingPath.Reset();
}
this.Invalidate();
}