Question

如何使用鼠标拖动（之前使用鼠标拖动绘制）将三角形移动到新位置？

...
java.util.List<Polygon> triangles = new LinkedList<Polygon>();
Point startDrag, endDrag, midPoint;
Polygon triangle;
...
public PaintSurface() {     
  this.addMouseListener(new MouseAdapter() {
  public void mousePressed(MouseEvent e) {
    startDrag = new Point(e.getX(), e.getY());
    endDrag = startDrag;
    repaint();
  }//end mousePressed   

public void mouseReleased(MouseEvent e) {
...
  int[] xs = { startDrag.x, endDrag.x, midPoint.x };
  int[] ys = { startDrag.y, startDrag.y, midPoint.y };      
  triangles.add( new Polygon(xs, ys,3));                    
  startDrag = null;
  endDrag   = null;
  repaint();
 }//end mouseReleased   
...


 });//end addMouseListener

  this.addMouseMotionListener(new MouseMotionAdapter() {

/ *我不知道如何将整个三角形移动（拖动）到新位置，然后删除之前绘制的三角形。 mouseDragged方法只使用鼠标拖动绘制一个新的三角形:-( * /

    public void mouseDragged(MouseEvent e) {
        endDrag = new Point(e.getX(), e.getY());
        repaint();
     }//end mouseDragged
        }//end paintSurface       

         //Draw triangles
         public void paint(Graphics g) {
           Graphics2D g2 = (Graphics2D) g;
           g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

           //draw the thickness of the line
           g2.setStroke(new BasicStroke(1));
           g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.00f));        
           g2.setPaint(Color.black);//set the triangle color 
           for (Polygon triangle : triangles)  g2.drawPolygon(triangle);
             if (startDrag != null && endDrag != null) {
                g2.setPaint(Color.red);
                g2.drawPolygon(triangle);   
             }   
          }//end paint       

              }//end private class PaintSurface

Answer 1

当您开始拖动时，您必须检测当前鼠标位置是否位于现有多边形之一上，同时标记起始位置

当你不添加新的多边形时，你可以将移动的数量添加到现有多边形的不同点并重新绘制

使用鼠标拖动绘制三角形（如何使用鼠标拖动移动上一个绘制的三角形）

1 个答案: