Thema in zeichnen von Linien, während Sie die Maus ziehen

Arbeite ich auf einem Farb-applet, das zeichnet verschiedene Formen. Ich möchte, um Linien zu zeichnen, während Sie die Maus ziehen. Das problem ist, dass wenn die Zeilen erscheinen, sind Sie wie im Bild unten gezeigt.

Thema in zeichnen von Linien, während Sie die Maus ziehen

Habe ich die Klasse Linie, die konstruiert wird, mit einem Punkt (Startpunkt)
und es hat eine Methode namens setDragPoint nimmt, dass die Maus bewegen Sie die Punkte, um zu malen, Linien ziehen, während auch die drawingImage macht zu viele flackert beim zeichnen im ziehen-Modus. Warum ist das passiert?

import java.applet.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;

public class PaintBrush extends Applet implements MouseListener, MouseMotionListener {

Shape shape;
Point startPoint;
Point dragPoint;
ArrayList<Shape> shapes;
Choice shapeChoice;
Choice colorChoice;
Choice fillChoice;
Image drawingImage;
Graphics drawGraphics;
String shapeString, colorString, fillString;
boolean isDragMode;

public void init() {
    shapes = new ArrayList<Shape>();
    shapeChoice = new Choice();
    shapeChoice.addItem("Line");
    shapeChoice.addItem("Rectangle");
    shapeChoice.addItem("RoundRect");
    shapeChoice.addItem("Oval");
    shapeChoice.addItem("FreeHand");

    add(shapeChoice);

    colorChoice = new Choice();
    colorChoice.addItem("Red");
    colorChoice.addItem("Green");
    colorChoice.addItem("Blue");

    add(colorChoice);

    fillChoice = new Choice();
    fillChoice.addItem("Filled");
    fillChoice.addItem("Hollow");
    add(fillChoice);

    shapeString = shapeChoice.getSelectedItem();
    colorString = colorChoice.getSelectedItem();
    fillString = fillChoice.getSelectedItem();

    drawingImage = createImage(getSize().width, getSize().height);
    drawGraphics = drawingImage.getGraphics();
    System.out.println("set up image");
    drawGraphics.setColor(Color.black);
    drawGraphics.fillRect(0, 0, getSize().width, getSize().height);
    drawGraphics.setColor(Color.orange);
    drawGraphics.drawRect(0, 0, getSize().width - 1, getSize().height - 1);
    drawGraphics.drawRect(1, 1, getSize().width - 3, getSize().height - 3);
    startPoint = new Point(0, 0);
    dragPoint = new Point(0, 0);
    addMouseListener(this);
    addMouseMotionListener(this);
}

public void mouseEntered(MouseEvent e) {
}

public void mouseExited(MouseEvent e) {
}

public void mouseClicked(MouseEvent e) {
}

public void mousePressed(MouseEvent e) {

    System.out.println("Pressed");

    startPoint.x = e.getX();
    startPoint.y = e.getY();
    repaint();

    switch (shapeString) {
        case "Line":
            shape = new Line(startPoint.x, startPoint.y);  //step 1 here i construct a new line using the start point (the point at which the mouse is pressed)

            break;
        case "FreeHand":
            shape = new FreeShape();
            break;
    }


    }

public void mouseReleased(MouseEvent e) {
    if (isDragMode) {
        shapes.add(shape);
        isDragMode = false;
     }
    repaint();

}

public void mouseMoved(MouseEvent e) {
}

public void mouseDragged(MouseEvent e) {
    System.out.println("Dragged");
    isDragMode = true;
    dragPoint.x = e.getX();
    dragPoint.y = e.getY();

    switch (shapeString) {
        case "Line":
            shape.setDragPoint(dragPoint.x, dragPoint.y);  //here i set the drag points to the already created line at step 1 
              break;
        case "FreeHand":
            shape = new FreeShape();
            break;
    }

    shape.drawWhileDragging(drawGraphics); //i call this method to draw while mouse is dragging

    repaint();


}

public void paint(Graphics g) {

  update(g);
}
 public void update(Graphics g) {

  //create an off-screen graphics drawing environment if none
  //existed
  //or if the user resized the applet drawing area to a different
 //size
   if (drawingImage == null)
{

System.out.println("Image is Null");
    drawingImage = createImage(getSize().width,getSize().height);
drawGraphics = drawingImage.getGraphics();
}



  //erase the previous image
  drawGraphics.setColor(Color.black);
  drawGraphics.fillRect(0,0,getSize().width,getSize().height);
  drawGraphics.setColor(Color.orange);
  drawGraphics.drawRect(0,0,getSize().width-1,getSize().height-1);
  drawGraphics.drawRect(1,1,getSize().width-3,getSize().height-3);  

   for(Shape s:shapes)
         s.draw(drawGraphics);

  //paint the offscreen image to the applet viewing window
  g.drawImage(drawingImage,0,0,this);

   }
 }


abstract class Shape {

Color shapeColor;
boolean filled;

abstract void draw(Graphics g);

void drawWhileDragging(Graphics g) {
}

void setDragPoint(int x, int y) {
}
}

 class Line extends Shape {

private Point startPoint;
private Point currentPoint;

public Point getStartPoint() {
    return startPoint;
}

public Point getCurrentPoint() {
    return currentPoint;
}

public void setStartPoint(Point point) {
    this.startPoint = point;
}

public void setCurrentPoint(Point point) {
    this.currentPoint = point;
}

void drawWhileDragging(Graphics g) {
    g.drawLine(startPoint.x, startPoint.y, currentPoint.x, currentPoint.y); 
}

public void draw(Graphics g) {
    g.drawLine(startPoint.x, startPoint.y, currentPoint.x, currentPoint.y);
}

Line() {
    startPoint = new Point(0, 0);
    currentPoint = new Point(0, 0);
}

Line(int x1, int y1) {
    this();
    this.startPoint.x = x1; 
    this.startPoint.y = y1;
}

void setDragPoint(int x, int y) {
    this.currentPoint.x = x;
    this.currentPoint.y = y;
    System.out.println("Current-X:" + currentPoint.x + " currentPoint-Y" + currentPoint.y);
    System.out.println("start-X:" + startPoint.x + " startPoint-Y" + startPoint.y);
  }

 }

class FreeShape extends Shape {

private ArrayList<Point> dragPoints = new ArrayList<Point>();

public ArrayList<Point> getDragPoints() {
    return dragPoints;
}

public void setDragPoints(Point point) {
    dragPoints.add(point);
}

public void draw(Graphics g) {
}

public FreeShape() {
  }
}


class Rectangle extends Shape {

public void draw(Graphics g) {
   }
 }


class Oval extends Shape {

public void draw(Graphics g) {
   }
 }
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InformationsquelleAutor Java Player | 2012-12-29
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