Grafica - DrawLine - traccia la linea e spostala

Question

Nel mio programma .net C# disegno poche righe usando i valori delle caselle di testo (io uso la funzione DrawLine). Voglio essere in grado di spostare una di queste linee cliccandoci sopra e spostando questa linea con il mouse - è possibile?

Answer 1

public class LineMover : Form 
{ 
    public LineMover() 
    { 

    this.DoubleBuffered = true; 

    this.Paint += new PaintEventHandler(LineMover_Paint); 
    this.MouseMove += new MouseEventHandler(LineMover_MouseMove); 
    this.MouseDown += new MouseEventHandler(LineMover_MouseDown); 
    this.MouseUp += new MouseEventHandler(LineMover_MouseUp); 

    this.Lines = new List<GraphLine>() 
    { 
     new GraphLine (10, 10, 100, 200), 
     new GraphLine (10, 150, 120, 40), 
    }; 
    } 

    void LineMover_MouseUp(object sender, MouseEventArgs e) 
    { 
    if (Moving != null) 
    { 
     this.Capture = false; 
     Moving = null; 
    } 
    RefreshLineSelection(e.Location); 

    } 

    void LineMover_MouseDown(object sender, MouseEventArgs e) 
    { 
    RefreshLineSelection(e.Location); 
    if (this.SelectedLine != null && Moving == null) 
    { 
     this.Capture = true; 
     Moving = new MoveInfo 
     { 
      Line = this.SelectedLine, 
      StartLinePoint = SelectedLine.StartPoint, 
      EndLinePoint = SelectedLine.EndPoint, 
      StartMoveMousePoint = e.Location 
     }; 
    } 
    RefreshLineSelection(e.Location); 
    } 

    void LineMover_Paint(object sender, PaintEventArgs e) 
    { 
    e.Graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; 
    e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 
    foreach (var line in Lines) 
    { 
     var color = line == SelectedLine ? Color.Red : Color.Black; 
     var pen = new Pen(color, 2); 
     e.Graphics.DrawLine(pen, line.StartPoint, line.EndPoint); 
    } 
    } 
    void LineMover_MouseMove(object sender, MouseEventArgs e) 
    { 
    if (Moving != null) 
    { 
     Moving.Line.StartPoint = new PointF(Moving.StartLinePoint.X + e.X - Moving.StartMoveMousePoint.X, Moving.StartLinePoint.Y + e.Y - Moving.StartMoveMousePoint.Y); 
     Moving.Line.EndPoint = new PointF(Moving.EndLinePoint.X + e.X - Moving.StartMoveMousePoint.X, Moving.EndLinePoint.Y + e.Y - Moving.StartMoveMousePoint.Y); 
    } 
    RefreshLineSelection(e.Location); 
    } 

    private void RefreshLineSelection(Point point) 
    { 
    var selectedLine = FindLineByPoint(Lines, point); 
    if (selectedLine != this.SelectedLine) 
    { 
     this.SelectedLine = selectedLine; 
     this.Invalidate(); 
    } 
    if (Moving != null) 
     this.Invalidate(); 

    this.Cursor = 
     Moving != null ? Cursors.Hand : 
     SelectedLine != null ? Cursors.SizeAll : 
      Cursors.Default; 

    } 



    public List<GraphLine> Lines = new List<GraphLine>(); 
    GraphLine SelectedLine = null; 
    MoveInfo Moving = null; 


    static GraphLine FindLineByPoint(List<GraphLine> lines, Point p) 
    { 
    var size = 10; 
    var buffer = new Bitmap(size * 2, size * 2); 
    foreach (var line in lines) 
    { 
     //draw each line on small region around current point p and check pixel in point p 

     using (var g = Graphics.FromImage(buffer)) 
     { 
     g.Clear(Color.Black); 
     g.DrawLine(new Pen(Color.Green, 3), line.StartPoint.X - p.X + size, line.StartPoint.Y - p.Y + size, line.EndPoint.X - p.X + size, line.EndPoint.Y - p.Y + size); 
     } 

     if (buffer.GetPixel(size, size).ToArgb() != Color.Black.ToArgb()) 
     return line; 
    } 
    return null; 
    } 

    public static void Main() 
    { 
    Application.Run(new LineMover()); 
    } 
} 

public class MoveInfo 
{ 
    public GraphLine Line; 
    public PointF StartLinePoint; 
    public PointF EndLinePoint; 
    public Point StartMoveMousePoint; 
} 
public class GraphLine 
{ 
    public GraphLine(float x1, float y1, float x2, float y2) 
    { 
    this.StartPoint = new PointF(x1, y1); 
    this.EndPoint = new PointF(x2, y2); 
    } 
    public PointF StartPoint; 
    public PointF EndPoint; 
}